A59: Timing of song onset during assymetric vocal interactions in birds: implications for additional receivers. Naguib, M., Fichtel, C; & Todt, D.

A61: Parental behaviour in relation to experimentally manipulated Great Tit brood sex ratio. Oddie, K.R., Lessells, C.M. & Mateman, A.C.

A62: Activity budgets of breeding Southern Masked-Weavers Ploceus velatus. Oschadleus, H.D.

Arnold, K.E. & Owens, I.P.F. 1998. Co-operative breeding in birds: Life history is the key. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 241.

Co-operative breeding is a strategy in which more than a pair of individuals are involved in the rearing of offspring. A modern comparative method was used to correlate variation in co-operative breeding in birds with certain life history traits. Data on 197 co-operatively and non-co-operatively breeding birds from all over the world were collated from the literature. The level of co-operative breeding was found to be highly significantly inversely correlated with annual adult mortality and clutch size, and positively correlated with the proportion of males to females. Annual mortality and clutch size were both found to be correlated with the total temperature range experienced by a species across its distribution. So, do certain lineages have an evolutionary predisposition to co-operative breeding due to their life histories, or can co-operative breeding influence life history? To answer this, a second comparative analysis was performed using family-typical life history values (from non-co-operative breeders) and correlating them with the proportion of co-operatively breeding species in that family. Families with low mortality are predisposed to co-operative breeding. A stable climate, resulting in a predictable food supply, enables territories to be defended all year round. The breeding habitat of co-operatively breeding species is saturated, not because of any intrinsic feature of the habitat itself, but due to the low population turnover. By breeding co-operatively, species further increase their probability of survival and an associated decrease in fecundity occurs.

Key words: co-operative breeding, comparative analysis, life history, ecology, behaviour

Castro Astor, I.N., Cavalcanti, R.B. & Alves, M.A.S. 1998. Spatial distribution and display behaviour of sympatric manakins in the Atlantic forest of Brazil. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 241.

Manakins are neotropical birds remarkable by the male colours and their display behaviour in leks. We studied three sympatric species of manakins, Pipra rubrocapilla, P. pipra and Manacus manacus, to compare the male dispersion patterns and the structure of their leks (particularly for P. rubrocapilla, unknown in the literature) and also their display behaviour. We carried out the study in a secondary area of lowland Atlantic Forest at the Biological Reserve of Poco das Antas, Rio de Janeiro. We captured and individually marked 207 individuals, including 33 P. rubrocapilla, 37 P. pipra and 137 M. manacus. Pipra rubrocapilla and P. pipra showed exploded leks while M. manacus was confirmed as having classical leks. Copulation and lek inspection by sub-adult males was described for P. rubrocapilla and P. pipra, and we identified a new collective behaviour of male exhibition for P. pipra.

Key words: Pipra rubrocapilla, Manacus manacus, lekking, female choice, mating system

Bell, B.D., Borowiec, M. & Lontowski, J. 1998. Does the complex song of the Marsh Warbler Acrocephalus palustris act as an "acoustic peacock's tail"? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 242.

The Marsh Warbler has one of the most variable song repertoires of any Acrocephalus species. Analysis of such a complex song signal provides much heterogeneity with which to test the hypothesis that the song acts as an "acoustic peacock's tail" which advertises male quality to the female. To what extent does complexity vary within and between neighbouring males, and how does this relate to their breeding success? To address such questions, the song repertoires of male Marsh Warblers were recorded in a colour-ringed population near Wroclaw, SW Poland, during 1997. Song repertoire parameters for each bird were determined from sonographic analysis and these were then related to individual arrival patterns, pairing dates and breeding success. From such analyses, the extent to which song elaboration relates to male fitness was then assessed. Finally, song complexity across a range of Acrocephalus species is discussed in relation to differences between the species and/or their respective breeding environments.

Key words: mating system, breeding success, fitness, Passeres, sexual selection

Bhatt, D. & Kumar, A. 1998. Singing behaviour in Oriental Magpie-Robin Copsychus saularis. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 242.

Breeding behaviour of Indian birds have been studied extensively, but systematic studies on song behaviour are lacking. In this paper we report singing activity of one of the famous songbird of the Indian sub-continent viz. Oriental Magpie-Robin Copsychus saularis. The songs and call-notes of the four male birds were observed and recorded in their territories in and around Gurukul Kangari University campus, Haridwar (29° 55’ N, 78° 8’E). Males were found singing from mid March to July last week. However, the dates of onset and termination of song varied from individual to individual, in their respective territories. Observations revealed that in male Oriental Magpie-Robin onset of song was dependant on the initiation of female song and the termination of song was found associated with the termination of incubation period. Three categories of songs with a varied range of frequency of notes and about six types of call-notes have been identified, Song Oriental Magpie-Robin is of complex type and varied in structure, composed of about 45 types of syllables. Emergence song has a low frequency range as compared to territorial or mate acquisition songs. A given song type vary in duration, amplitude and rate of delivery. Each male uses a repertoire of different song phrases.

Key words: vocalisation, song, breeding, territory

Bretagnolle, V., Arroyo, B. & Mougeot, F. 1998. Nest defence in Montagu's Harrier: Assessing the effects of coloniality, predation risk and offspring survival prospects. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 243.

Among potential benefits of colonial breeding, defence against predators is of major importance. We investigated experimentally this potential benefit in a semi-colonial raptor, the Montagu’s Harrier Circus pygargus. Pairs in different colonial contexts (solitary, small or large colonies) were presented a predator decoy (crow, fox or owl), associated or not with a playback of either a harrier alarm call or a control call. Time before detection, alarm calling, attack rate and recruitment were recorded during 15 min tests (n = 250), that were conducted in four study areas (France and Spain) over three breeding seasons. We found that: (1) Detection probability, recruitment and overall attack rate increased with nest-clumping degree. (2) Playbacks of alarm calls enhanced detection, especially at colonies. (3) Detection and attack rate varied with adult sex, predator type and breeding stage, being higher in females, late in the season and when predation risk was higher. (4) Detection probability, alarm calling and attack rates were higher during good-food years, when adult condition and offspring survival prospects were higher. (5) Anti-predator behaviours were related to locally experienced predation risk, as revealed by between-study area comparisons. We suggest that the anti-predator benefits might be a valuable reason for coloniality in this species.

Key words: coloniality, predator detection, nest defence, Circus pygargus

 

A07: Food hoarding in a non-territorial population of the Coal Tit Parus ater

Brotons, L. 1998. Food hoarding in a non-territorial population of the Coal Tit Parus ater. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 243.

Territoriality is suggested to favour food hoarding by reducing intraspecific cache robbery. A strong association between winter territorial Parus species and the storing habit has been suggested. In the Pyrenees range, I studied hoarding in a non-territorial population of the Coal tit. The habitat is optimal for the species and its density very high. Colour-ringed individuals were followed during autumn and winter and were found to hoard food intensively in both seasons. Presence of conspecifics in a 5 m radius, diminished the probability that the birds stored food, but in groups, Coal tits still cached food items when companions were further than 5 m away. Focal birds tended to cache closer to the core of their home ranges than expected by chance. However, individuals overlapped both in the distribution of their caches and their position within trees. The study shows that hoarding can be reconciled with non-exclusive use of territories via non-random choice of the moment that the cache is done and of its spatial location. This study would support the hypothesis that, in the genus Parus, hoarding behaviour might have originated in a non-territorial species. Later on, more northern populations would have benefited to a greater extent from hoarding by strengthening the exclusive use of territories where caches are located.

Key words: storing, spacing behaviour, tits, caching

 

Brumm, H., Hultsch, H., Ambrugger, P. & Todt, D. 1998. Song amplitude varies with song quality during the vocal development of nightingales. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 243-244.

Like other songbirds, nightingales Luscinia megarhynchos are continuous songsters during their early song development. Still, a given performance can be categorised into phases, when males produce many imitations of acquired model songs and others that are composed mainly by non identifiable song material. The temporally clumped occurrences of imitations during singing suggests that these reflect episodes of pattern retrieval from the bird's memory. To further examine this idea we studied the development of sound intensity during vocal ontogeny, that in nightingales covers a period of several months. The overall increase in vocal amplitude along with the progression of development could be specified as follows: during the first three months of plastic singing, performance phases with high numbers of imitations were produced consistently with a higher amplitude than phases with low numbers of imitations. Towards song crystallisation, when performances became more homogenous with respect to imitation numbers, amplitude differences could no longer be assessed. Our findings suggest that young birds monitor the 'quality' of their vocalisations. Mechanisms of sensorimotor feedback may account for producing those vocal patterns with high volume that match auditorily acquired information. This study was supported by the BBAW.

Key words: birdsong, nightingales, song development, vocal amplitude, song retrieval

Bures S., Pavel V., Skrivan P., & Horackova K. 1998. Evolutionary aspects of differences in nest defence behaviour in open- and hole-nesting passerines. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 244.

Predation is considered an important selective agent in the evolution of behavioural characteristics of animals. We studied nest defence behaviour in Pied Flycatcher Ficedula hypoleuca (cavity-nesting) and Meadow Pipit Anthus pratensis (open-nesting) in presence of models of their the most important predators in the Czech Republic from 1995 to 1997. The Meadow Pipit nest defence behaviour was primarily determined by the parent’s effort to not disclose the nest site and differed due to scanning mechanisms used by the individual predator species when searching for prey. The parents silenced their nestling in presence of a predator. Nestling did not call until 5 days old and frequency of begging calls was low during a day. By contrast, such behaviour was not registered in the Pied Flycatchers in which nestling begin to call shortly after hatching. The females of both the species timed their visits to the nest after removal of a predator model in response to body temperature of young exothermic nestlings. Different antipredatory behaviours observed in the studied species have evolved due to different concealment and this vulnerability of their nests to predators.

Key words: nest defence, anti-predator behaviour, selection, Ficedula hypoleuca, Anthus pratensis

Calf, K., Adams, N. & Slotow, R. 1998. Dominant individuals in flocks of Bronze Munias benefit thermally from huddling under winter conditions. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 244.

Thermoregulation during the winter nights is energetically expensive for Bronze Munias Lonchura cucullata as they are small endothermic organisms with high metabolic rates. Bronze Munias form flocks during winter characteristically huddling in nests at night. We investigated if there were thermal benefits associated with dominance within flocks of Bronze Munias. Munias only entered torpor as a response to poor condition. Dominant munias had preferential access to resources, namely taking up the central position within the huddled flock. There was, however, no correlation between position within the huddle and mass loss. Temperature influenced metabolism, since individuals in huddles and singletons lost more mass at 5 °C than at 25 °C. Huddling did not have a beneficial affect on metabolic rate as individuals that were in groups lost more mass than those that were single. Initial mass was found to influence mass loss, with heavier dominants in flocks losing more weight than lighter singletons. Dominants may have higher metabolic costs associated with increased competition despite benefiting thermally from the central position in the huddle.

Key words: priority access, mass loss, torpor, thermoregulation, sociality

Collias, N.E. 1998. Vocal signals of the Village Weaver: Spectrographic classification and the code of communication. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 245.

Vocal signals of a species are social signals and guides to its social life. Sonograms were made of 21 of the 26 vocal signals of the Village Weaver Ploceus cucullatus. A spectrographic key to vocal signals helps make these signals comparable for different investigators. Short distance contact calls are given in favorable situations and are characterized by low amplitude and great brevity of notes. Alarm cries are longer, louder and often-strident calls with much energy at high frequencies, while threat notes, also relatively long and harsh, emphasize lower frequencies. Each male displays his newest nest in a colony with an individually distinctive call to unmated females. The most harmonic calls of the species include a loud call by a male when an unmated female first enters his nest, and also very soft, brief notes given by parent birds to attract a fledgling. Males use somewhat different songs to defend territory, for courtship, or for advertisement. Vocal signals are composed of basic elements that vary in duration, frequency, loudness, and tonality of notes, and these variations can be arranged in pairs of opposite extremes serving to reduce ambiguity in signals, in effect a code.

Key words: Ploceus cucullatus, Africa, structural rules

Collins, S.A. & Goldsmith, A.R. 1998. Individual identification from vocalisations of Common Coturnix coturnix, Japanese C. japonica, and a hybrid quail. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 245.

Many types of information can be conveyed by bird calls such as species, status and individual identity. However, there may be conflict between the variability necessary for individual identification and the stereotypy necessary for species identification. Recently domesticated Japanese quail have been released in Europe, and are competing for food and mates with the Common quail. Furthermore hybrids have been found. The crow of both subspecies of quail attracts conspecific females, thus inter sub-species vocal competition will become very important. We examined which parameters best discriminated between individuals, and which between the two sub-species and hybrids. Sonograms were made from recordings of crows of individual Japanese, Common and hybrid quails and analysed. Parameters describing the time structure of the crow discriminated best between individuals, and showed the greatest differences between the two sub-species and the hybrid. Hybrid crows were extremely variable, with an individual often producing more than one crow type, and occasionally including those from both sub-species. However, hybrid individuals could still be identified by their crow parameters. This work provides a basis for investigating how crow parameters evolve where the wild common and domesticated Japanese quail are sympatric.

Key words: vocalisations, quail, individual discrimination, speciation

Crafford, D., Ferguson, J.W.H. & Kemp, A.C. 1998. Why do African Grass-owls Tyto capensis produce clicking calls? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 245-246.

While hunting, African Grass-owls Tyto capensis emit clicking calls over extended durations. The peak energy of these clicks is at 2 KHz. This is exceptional among owls. Three hypotheses exist for explaining these calls: (1) They constitute a rudimentary form of echolocation. (2) They function to activate prey so that these become more visible to the owl or (3). They function for intraspecific communication. Field work as well as laboratory experiments were performed to test these hypotheses. A microphone was implanted inside the ear of a dead Grass-owl. Laboratory measurements of sound pressure levels emanating from electronically generated sounds from different spatial orientations indicate that the grass owl has no directional sensitivity at 2 KHz. Directional sensitivity at frequencies above 8 KHz is acute. Grass-owls also click more frequently during periods of ample moonlight. These observations falsify the echolocation hypothesis. Laboratory experiments were performed in playing Grass-owl clicks to rodents (Otomys angoniensis and Mastomys natalensis) captured in African Grass-owl territories. The rodents ignored the owl vocalisations, reacting in similar ways to owl clicks and control sounds and thus falsifying the second hypothesis. Field observations suggest that Grass-owl clicks serve for intraspecific communication.

Key words: communication, predator-prey interactions, vocalisation

Crasselt, C.A., Wanker, R. & Franck, D. 1998. Development of contact calls of Spectacled Parrotlets Forpus conspicillatus and its significance for sibling recognition. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 246.

In Spectacled Parrotlets the formation of long-term sibling bonds is fundamental for the offspring’s integration into the social system. Adults were able to discriminate between contact calls of their pair mates and other group members in playback experiments. This suggests that individual recognition by contact calls may also play a role in the formation of sibling groups. Contact calls were audio recorded in regular intervals from hatching up to the formation of stable pair bonds. Furthermore playback experiments were performed at different stages of the ontogeny. Finally the contact calls of the parents and their offspring were compared by sonagraphic analyses. This gave hints on the involvement of learning during the vocal development. The contact calls originated from extremely short calls which were uttered for the first time on day three or four post hatching. At fledging the calls of the siblings showed clear similarities, but were different from adult contact call structure. At post fledging stage we found first preliminary evidence for sibling recognition. We suggest that the development of short contact calls in Spectacled Parrotlets follows a similar developmental pathway to that currently suggested for song learning in songbirds.

Key words: Spectacled Parrotlets, sibling recognition, vocal development, contact calls, Forpus conspicillatus

Csermely, D. 1998. Evidence of bias in the footedness to capture terrestrial prey in birds of prey. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 246.

Our knowledge of the preferential use of limbs for feeding (footedness) in birds is still limited. Birds of prey are good candidates for such a study as they use feet to grasp prey, particularly when this occurs on the ground. I analysed the patterns of several successful predatory attempts by rehabilitated individuals of several species of hawks and owls. When rehabilitated they are routinely tested to assess their probability of successful release. The birds were usually individually offered one laboratory mouse, but other species, ranging from small rat to one-day-old chicken or earthworm, were used as well. The foot used and other parameters of predatory behaviour were considered. The results show that hawks, Common Buzzard Buteo buteo and Kestrel Falco tinnunculus tended to grasp prey with one foot only, but without laterality. In contrast, Barn Owl Tyto alba and Tawny Owl Strix aluco used generally both feet, although the latter species showed also some laterality in favour to the right foot. It is worth noting that the Little Owl Athene noctua, which is one of the most "diurnal" owl species, showed a strong preference for using the right foot only. These findings show how there are various degrees of footedness, likely at population level, between those species. Moreover, the bias recorded between species seems more related to environmental constraints, principally the light, than to phylogenetic similarity.

Key words: behaviour, predation, birds of prey, raptors, phylogeny

Cygan, J.P. & Jablonski, P. 1998. Painted Redstart Myioborus pictus song activity during breeding season. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 247.

The Painted Redstart is a small passerine (temporarily monogamous) bird with monomorphic and contrast plumage whose role and evolution are not well understood. We studied territorial song of this species during breeding season (March to June 1996 and 1997), counting number of songs per three minutes (repeated after 2 minutes). Every time we noted status of a male and context (presence of other singing males, female, nest or nestlings). Unlike the most of passerine species, male Painted Redstarts sing most actively before mate acquisition (13.0 times/3 min when alone and 16.3 times/3 min with presence of other singing territorial male and 14.5 times/ 3 min with another pair). Paired birds sang much less frequently (5.5 times/3 min with females and 9.6 times/3 min when another male or pair were present in neighbouring territory). Males sang least frequently while there were nestlings in the nest (2.5 times/3 min.). We also observed females singing (about 3 times/3 min.), but only shortly after pairing. The different strategy (males singing less frequently after pairing) may be explained by relatively high male participation in nestling feeding and female participation in territory defence.

Key words: song, behaviour, territoriality, breeding

da Silva, M.L. & Vielliard, J.M.E. 1998. Repertoire size of the Rufous-bellied Thrush Turdus rufiventris relate to environment and populational factors. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 247.

The song repertoire of the Rufous-bellied Thrush Turdus rufiventris is highly variable among individuals, and we searched for extrinsic factors affecting repertoire. We measured physical parameters of the notes, classifying them into structurally defined types, and transcribing their sequences for each of 44 individuals recorded in 24 localities covering the full range of the species. We tried to identify fixed patterns for species-specific recognition, and possible correlation between the size of the individual repertoire and extrinsic environmental and population factors. We made sonograms of all recorded songs, and identified each note type, classifying them into a "dictionary". We concluded that the dictionary for Turdus rufiventris will never be completed because the diversity among individuals is so great. The proportion of the note types shared between individuals is very small, and there are no local characters indicating the existence of regional dialects. Note sequencing varies within individuals, characterising the song as versatile. Among the extrinsic factors tested, only population density may influence the repertoire size, showing a significant inverse correlation: smaller repertoires are encountered in high density populations. Disturbance in urban areas was not significantly correlated with repertoire size.

Key words: song, Brazil, repertoire, bioacoustics, populational factors

Dale, J. 1998. Significance of variation in breeding plumage of male Red-billed Queleas Quelea quelea: Evidence against condition dependence. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 247-248.

A common explanation for the evolution of bright plumage is that plumage colour is an honest signal of phenotypic quality. Under this model, receivers of the signal (potential mates or sexual rivals) are selected to pay attention to traits that predict their bearer's capacity to provide benefits to offspring (e.g. good genes or parental care) or that reveal their bearer's fighting ability, strength or dominance. Since costs of plumage colour are thought to be high, only individuals in good condition can afford to display maximum colouration. Red-billed Queleas are unusual in that males moult into a highly variable breeding plumage. Within Zimbabwean populations, the heads and breasts of males varied from pale yellow to bright red, while their facial mask patterns ranged from pure white to jet black. Predictions based on the idea that plumage colour is a sexually selected indicator of quality were not supported: Plumage hue did not correlate with reproductive success, age, or phenotypic condition. Furthermore, plumage colouration appears to be strongly heritable and is probably based on a few alleles rather than on the overall genetic, and hence phenotypic, quality of the individual. Finally, different components of the plumage variation co-varied independently of each other which would not be expected if these traits indicated quality. An alternative hypothesis, that quelea plumage evolved to facilitate individual recognition among nesting males, is suggested.

Key words: plumage colour, plumage polymorphism, sexual selection, quality indicators, individual recognition

Delport, W., Kemp, A.C. & Ferguson, J.W.H. 1998. Individual variation of African Wood Owl Strix woodfordii hoot calls and implications in monitoring population dynamics. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 248.

The individual variation of African Wood-Owl Strix woodfordii hoot calls may aid the identification of individuals within a population. We recorded the calls of territorial wood owls, in response to playback, along the Levuvhu river, northern Kruger National Park, from 1986 to 1997. The hoot calls were analysed using the Avisoft Pro version 2.7 sonogram analysis package. Forty five (six frequency, twenty shape and nineteen temporal) variables were measured from sonograms. Maximum frequency differences between sexes were audibly distinguishable. Therefore low and high frequency calls were analysed independently in a forward-stepwise discriminant function analysis. Individual wood owl calls were correctly classified, with greater than 95% success in both low and high frequency groups, with the use of only five temporal and one frequency variable. The unique properties of wood owl hoot calls coupled with the sampling technique of recording at distance intervals on the road adjacent to the Levuvhu River, suggest the long term research of the wood owl population to be feasible. We were able to identify changes of territory members occurring in the 11 year observation period and to make statements about the nature of these territory changes. The individual variation of hoot calls are therefore useful in studying the long term dynamics of the Levuvhu river wood owl population.

Key words: communication, multivariate analysis, territoriality

 

Doutrelant, C. & Lambrechts, M.M. 1998. Trills in Blue Tit songs: A shifted character due to competition with Great Tit? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 248.

Blue Tits Parus caeruleus, as many other species, show much geographic variation in their songs. Songs that include a trill (series of rapidly repeated notes) dominate the song repertoires of Blue Tits over a large geographical area on the European continent. By contrast, these songs with trill have never been reported in North Africa, the Canary Islands, and in some parts of the island of Corsica. The syntax of many Blue Tit songs without trill is similar to that of Great Tit Parus major songs, and dominate the song repertoires in populations where great tit densities are low. By contrast, the syntax of Blue Tit songs with trill differs much from that of great tit songs, and is especially observed in populations where Great Tit densities are high. Because in many populations, Great and Blue Tits are in close competition for resources (e.g. nest sites), and Blue Tits are mostly dominated by the larger Great Tit, we suggest that the Blue Tits songs with trill are a result of a character shift in syntax to facilitate species recognition, and this to minimise interspecific territorial interactions with Great Tits. We present results of playback experiments and comparative studies which are compatible with an ecological character shift due to competition for acoustic space between two birds.

Key words: interspecific competition, song, cultural evolution, Parus caeruleus, Parus major

1Projet Terpsiphone, Fort-Dauphin, Province de Tulear, Madagascar, e-mail cel@dts.mg, ²Australian National University, ACT, Australia

Emahalala, R.E. & Mulder, R.A. 1998. Tail elongation related to foraging behaviour of Madagascar Paradise Flycatchers Terpsiphone mutata. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 249.

Male Madagascar Paradise-Flycatchers are adorned with elongated tail streamers. The streamers are presumed to play a role in attracting females through sexual selection, but could also have a functional aerodynamic role. In this study, we compared the foraging behaviour of long-streamered with that of short-streamered individuals and females, and also the behaviour of normally long-streamered individuals to that of the same birds during the annual moult, when the streamers are temporarily lost. The following parameters were measured: foraging method, prey taxon, prey size, substrate and capture success, during two seasons.

Key words: flycatcher, foraging, streamers

 

A23: The singing of wild birds can reflect properties of song learning and memory

Institut für Zoologie, Technische Universitaet Muenchen, Muenchen, Germany, Freie Universitat Berlin, D-12163 Berlin, Germany, e-mail todt@zedat.fu-berlin.de

Fichtel, C. & Todt, D. 1998. The singing of wild birds can reflect properties of song learning and memory. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 249-250.

Recently, Beecher (1996. In Kroodsma, D.E. & Miller, E.H. (eds) Ecology and evolution of acoustic communication in birds: 61-78) claimed to extend the study of song learning to the field. Such an approach can be done either directly, i.e. by investigating the properties of song acquisition in free-ranging birds, or indirectly, i.e. by inferring properties of song memories through an inquiry into the system of singing rules. This paper deals with a study that applied the latter approach by examining the singing performances of territorial nightingales Luscinia megarhynchos. Subjects were five males who's nocturnal singing was recorded shortly after arrival at their breeding sites (location: Berlin). Sequential analysis of song-type successions confirmed that the birds' vocal repertoires (sizes: 147, 173, 203, 218 and 305 song-types) were not a mere aggregation of single song-types, but showed a hierarchical structure which was given by distinct clusters of sequentially associated song types. About 50% of the clusters had a size of 4 ± 2 song-types and revealed properties of the so-called packages. The remaining clusters were larger in size (8 to 16 song-types) and thus seemed comparable to the so-called context groups. Our results indicate the formation of 'subreperoires' described by Hultsch (1985. Verh. Dtsch. Zool. Ges. 1981: 240) and allow us to conclude that the song performance rules of wild birds can reflect song-type associations which are well-known from song learning research under controlled laboratory conditions (Hultsch, H. & Todt, D. 1989. J. comp. Physiol. A 165: 197-203).

Key words: bird song, nightingale, subrepertoires, song learning, Luscinia megarhynchos

 

Institut Verhaltensbiologie, Freie Universität, Haderslebenerstr. 9, D-12163 Berlin, Germany, e-mail Hultsch@Zedat.FU-Berlin.de

Geberzahn, N. & Hultsch, H. 1998. The role of song ontogeny in shaping individual performance profiles in Nightingales. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 250.

Songbirds with large vocal repertoires often show individually distinct profiles in the frequency of performing their different song-types. Factors involved in determining how often a song-type is used have been identified in the social domain, e.g. the singing routines of territorial neighbours. In our study we investigated the role of ontogeny in the formation of individual performance profiles. We examined whether and how (1) the amount of exposure to song-types during auditory song acquisition or (2) the amount of motor practice during vocal ontogeny would account for frequency profiles in the adult singing. The study was carried out on handraised Nightingales Luscinia megarhynchos. While the evidence was scant for influences of auditory exposure on the frequency of use, we obtained clear positive relationships between the ontogenetic 'age' of imitations (time of emergence) and the performance frequency of these song patterns. Our findings indicate that performance profiles of nightingales can be affected by intrinsic factors. We assume that vocal practice plays a role in selectively consolidating song-type memories, whose respective strengths then contribute to differential performance observed in the adult birds. This study was supported by the BBAW.

Key words: birdsong, song development, song type use, vocal rehearsal, Luscinia megarhynchos

Department of Vertebrate Zoology, Moscow State University, 119899, Moscow, Russia, e-mail golubeva@vgavrilov.home.bio.msu.ru

Golubeva, T.B. 1998. Ecological factors in the development of hearing in birds. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 251.

The role and perception of acoustic information in the early ontogeny of hearing are studied in 7 species (Anas platyrhynchos, Larus canus, L. argentatus, Sterna paradisaea, Asio otus, Coloeus monedula and Ficedula hypoleuca) with different types of ontogeny (precocial, semiprecocial, semialtricial, and altricial). The process of auditory development is divided into three stages, each having distinct boundaries and being characterised by definite correlative relations between the structure, function and the behaviour of the organism as a whole. Specific types of ontogeny underlie and determine temporal regularities and critical moments at each developmental stage. Every stage is determined by the certain energetic level of the developing organism. The onset of an intensive stage of hearing development is determined by the appearance of active breathing and vocalisation while the start of the concluding stage is determined by the onset of effective thermocontrol. The development of reflex activity of the middle ear muscle and the role of the growth of middle ear structures in auditory perception are studied. Parental vocalisation and own acoustic activity are indispensable conditions of adequate development and adaptive tuning of the auditory system. Acoustic stimulation has a direct effect on the development of the auditory epithelium by promoting its maturation.

Key words: vocalisation, hearing, ontogeny, stages of development, acoustics

Nimes Museum of Natural History, France; ²CNRS-CEBC, Villiers-en-Bois, France, e-mail breta@cebc.cnrs.fr

Gory, G., Mougeot, M. & Bretagnolle, V. 1998. Non-breeders colony attendance and competition for nest sites in the Common Swift. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 251-252.

Competition for nest-sites is likely to be enhanced at large bird colonies, especially when nest sites are limited like in hole-nesting species. We studied colony attendance and nest prospecting by non-breeders at a large Common Swift Apus apus colony located in south France. During the 1996 and 1997 breeding seasons, birds breeding within nest-boxes were individually tagged and controlled daily until laying to study colony occupancy, nest-site and mate changes. We also sampled a range of daily activities at the colony (screaming parties, vocal activity, nest intrusions and fights). We used the ratio of tagged birds in screaming parties to quantify colony attendance rate by non-breeders. In early prelaying, tagged birds of both sexes were found in parties. As laying approached, party size increased, as well as the proportion of non-breeders and most tagged birds then involved in parties were males. Party size, nest-intrusion rates and fight occurrence within nests significantly increased with colony attendance rate by non-breeders. Breeding birds, and especially males, might then join parties in response to nest intrusions. Despite frequent intrusions in extra-nests, few tagged individuals successfully changed nest-box. Frequent nest intrusions were mostly by non-breeders, and might have costs additional to competition for nest sites, such as egg falling and parasite transmission.

Key words: Apus apus, nest-site competition, non-breeders, screaming parties

Australian National University, Canberra, A.C.T., Australia, e-mail Michelle.Hall@anu.edu.au

Hall, M.L. & Magrath, R.D. 1998. Is duetting a mate-guarding tactic? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69:252.

Do avian duets reflect co-operation or conflict? Duets have been described as co-operative displays functioning to maintain the long-term monogamous pair bonds and year-round territories common to most duetting species. However, in some species where females initiate duets, males appear to use duets to guard females. We studied duetting in the Magpie-Lark Grallina cyanoleuca, a socially monogamous species which duets antiphonally, with females initiating about 40% of duets. We recorded information about vocalisations, distance between pair members and their movements relative to one another before the start of the breeding season, and when females were fertile. We found that males guarded fertile females by maintaining proximity and singing at a slightly higher rate. Fertile females moved away from their partners more and sang less, perhaps attempting to evade male guarding. However, males were less likely to respond antiphonally to the song of females when they were fertile than when they were not. So although male Magpie-Larks do guard females, they clearly do not use duetting as a mate-guarding tactic.

Key words: duet, mate-guard, co-operation, conflict, Grallina cyanoleuca

Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eotvos University, 1088 Budapest, Puskin u. 3., Hungary, e-mail yeti01@ludens.elte.hu

Hegyi, G., Michl, G., Toth, L., Garamszegi, L.Z. & Torok, J. 1998. Within-pair asymmetry of risk taking in the collared flycatcher: Co-operation or selfishness? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 253.

In the presence of birds of prey (a stuffed female Sparrowhawk) the Collared Flycatcher Ficedula albicollis parents interrupt provisioning of their offspring. After the disappearance of the Sparrowhawk, however, they are willing to continue parental care within a given time. The parent that first visits the nest-box was named the risktaker, while his/her partner was called the follower. Sharing of the roles between the parents depends on the condition of their young: The risktaker is more often a male in the case of good-quality offspring, and the female in the case of poor-quality offspring shows the opposite trend. Nevertheless, the degree of risk-taking by the follower does not depend on the quality of his/her offspring, but rather on the risk-taking behaviour of his/her partner, the risk-taker. Within-pair asymmetry in risk taking is high: The followers are willing to take a maximum of two-thirds of the risk taken by their partner. Although the follower is always near the nest-box, he/she will visit their offspring only after several risky visits made by the risk-taker. The degree of asymmetry in risk-taking is consistent with the number of risky visits. The results suggest that the behaviour of the follower is more co-operative than selfish and it might be important from the perspective of the survival of clutches under predatory threat.

Key words: predation pressure, risk-taking, co-operation, selfishness, Collared Flycatcher

University of Stellenbosch, 7600, South Africa

Henderson, C.L. & Cherry, M.I. 1998. Testing alternative hypotheses of provisioning in the Cape Sugarbird Promerops cafer. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 253.

This study attempted to test three hypotheses of provisioning in a field population of the Cape Sugarbird, Promerops cafer. This is a monogamous species with biparental care which displays extreme sexual dimorphism in tail-length during the breeding season. Earlier work on this species has shown that females were prepared to lay more eggs for males with longer tails. The possibility that females mated with longer-tailed males that provisioned the young more was investigated by recording parental provisioning over one-hour time-slots, daily, over the nestling phase. Female provisioning did not increase with increasing male tail-length, and females did not receive direct benefits in the form of increased male parenting if mated with longer-tailed males. There was no compensation provisioning within the pairs, instead a positive correlation intimating that if one partner fed more, the other partner fed more (facilitation).

Key words: provisioning, male tail-length, female choice

1FU-Berlin, Inst. für Verhaltensbiologie, Haderslebenerstr. 9, D-12163 Berlin, Germany, e-mail mnaguib@zedat.fu-berlin.de; ²TU Muenchen, Inst. für Zoologie, Lichtenbergstr. 4, D-85748 Garching, Germany

Hillmann, E., Teige, T., Griessman, B., Klump, G. & Naguib, M. 1998. Accuracy of ranging in songbirds: Evidence from playback experiments with computer-generated song degradation. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 253-254.

The distance of signalling conspecifics is an important piece of information in signals used in long-range communication. Playback studies in the field so far have shown that birds can use a variety of different acoustic cues to assess the distance of a signalling conspecific. To date, however, we have little information on the accuracy with which receivers can use these cues for ranging. Here, we aimed to investigate the accuracy in ranging by using songs that were degraded in a computer-simulated (virtual) forest. This signal-generation procedure allowed us to produce quantifiable and repeatable degrees of degradation. Playback experiments with chaffinches Fringilla coelebs showed a significant correlation between the amount of song degradation and the distance assessment of the birds reflected in their approach towards and beyond the sound source. This suggests that the birds perceived the different amounts of degradation as indicating different distances. However, subjects did not seem to have discriminated behaviourally between small differences of degradation. These results complement findings in laboratory experiments in another songbird species. The implication of these findings are discussed in light of the variation of acoustic properties of the environment and in relation to the cost and benefits in precisely assessing the distance of singing conspecific rivals.

Key words: communication, bird song, environmental acoustics, perception

Institut Verhaltensbiologie, Freie Universität, Haderslebener str. 9, D-12163 Berlin, Germany, e-mail Hultsch@Zedat.FU-Berlin.de

Hultsch, H., Geberzahn, N. & Schleuss, F. 1998. Song invention in nightingales: Cues from song development. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 254.

The vocal repertoire of handraised songbirds often contains song patterns that can not be identified as imitations and are therefore called inventions. The origin and role of such inventions is unclear. In our study we analysed the development of inventions in hand raised nightingales Luscinia megarhynchos, and examined especially: (1) relationships between the repertoire of inventions and the repertoire of imitations, and (2) the sequential succession of inventions and imitations during the singing of subjects. Our results show that the repertoire of imitations was inversely related to the repertoire of inventions: subjects classified as 'good learners' (high acquisition rate) tended to develop few inventions, whereas 'poor learners' (low acquisition rate) developed many of them. As the total size of song-type repertoires differed only slightly in these male classes, we assume that inventions are developed to reach a somehow preordained repertoire size which ranges around 70 song-types in first year nightingales. Sequential analyses revealed that inventions were not randomly interspersed between renditions of imitations. Rather they were performed as distinct clusters of sequentially associated song-types. Such a performance mode suggest that inventions indeed constitute a special song category during retrieval. This finding casts doubt on the view that inventions are developed from components of imitated songs.

Key words: bird song, song development, repertoire size, invented songs, Luscinia megarhynchos

1Queen's University, Kingston, Ontario, Canada, ²Canadian Wildlife Service, Hull, Quebec, Canada. Queen's University, Kingston, Ontario, Canada, e-mail friesenv@biology.queensu.ca

Ibarguchi, G., Gaston, A.J. & Friesen, V.L. 1998. Molecular evidence for kin groups within colonies of murres (Genus Uria). In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 254.

Geographic substructuring of animal populations into kin groups may have important consequences for evolution and behaviour. For example, it may accelerate rates of morphological evolution and speciation, promote ‘behavioural drive’, and lead to the evolution of kin selection. Indirect evidence from long-term population studies and mark-and-recapture techniques indicates that a wide variety of vertebrates may form kin groups. Nonetheless, the genetics of microgeographic structuring have been studied in only a few species of mammals, fish and co-operatively breeding birds. The generally weak large-scale differentiation in birds may have lead to a presumption that birds do not generally form kin groups, yet studies of mammals indicate that micro- and macrogeographic differentiation are independent. Murres (genus Uria) are colonial seabirds that breed on cliffs and offshore islands throughout the Northern Hemisphere. Indirect evidence from band returns and distributions of colour morphs of eggs, chicks and adults suggest that colonies may be subdivided into kin groups. We measured variation in proteins, mitochondrial DNA, and microsatellite loci among murres from two colonies, and found that birds on individual cliff ledges may represent extended kin groups with an average level of relatedness equivalent to first cousins. We also conducted mathematical analyses to elucidate the conditions under which kin groups could evolve in the presence or absence of large-scale genetic structuring.

Key words: protein, seabird, mitochondrial DNA, microsatellites, population genetic structure

Netherlands Institute of Ecology, Boterhoeksestraat 22, 6666 ZG Heteren, The Netherlands, e-mail incagli@cto.nioo.knaw.nl

Incagli, M. & Drent, P.J. 1998. Exploration and anti-predator behaviour in juvenile captive Great Tits. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 255.

In previous work we showed that juvenile Great Tits Parus major differ consistently in their exploratory behaviour and that these differences are related to aggressiveness, birds quicker to explore a novel environment being more aggressive. This study investigated whether these individual differences extend to anti-predator behaviour. Juvenile hand-reared Great Tits whose exploratory behaviour was known were trained to feed on an artificial tree in an aviary room. Each bird was successively observed in a five minute trial following a food deprivation time of an hour. No difference was found in either sex between fast and slow explorers in the time needed to approach the feeders tree and to eat the first food item and in the number of items eaten. When on a following test a model of a Little Owl Athene noctua was put on the feeder tree, female fast explorers were significantly quicker in approaching and eating time and ate significantly more items than female slow explorers. While the same tendencies, were observed in the males they were not significantly different (0.05 < P <0.2). It is suggested that the behaviour of the fast explorers agrees with an active style of coping with stress, while the behaviour of the slow explorers resembles a passive coping style.

Key words: Great Tits, individual differences, anti-predator behaviour, coping strategies

1University of Minnesota, St. Paul, MN, USA, e-mail johnson@biology.utah.edu, ²University of Michigan, Ann Arbor, MI, USA

Johnson, K.P., McKinney, F. & Sorenson, M.D. 1998. Adaptation and constraint in the evolution of male parental care in the dabbling ducks. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 255-256.

The dabbling ducks exhibit considerable variation male parental behaviour towards the young. The major hypothesis developed to explain this variation suggests that in species which have shortened breeding seasons there is no opportunity for males to provide parental care because of the importance of the moult migration. We tested this hypothesis by examining the evolutionary changes in male parental care by reconstructing ancestral states over a molecular phylogeny. Several gains in male care were reconstructed and these were strongly associated with the presence of long breeding seasons. These long breeding seasons are associated with species which are distributed in the tropics and Southern Hemisphere; however, there are several exceptions. These exceptions involve groups that have radiated relatively recently (according to genetic branch lengths). In addition, no species which has a shortened breeding season exhibits male parental care even though many of these species are sympatric with species which do show male parental care. These results suggest that both adaptation and phylogenetic constraint are involved in the evolution of male parental care in dabbling ducks.

Key words: parental care, phylogeny, dabbling ducks, Anas, constraints

1School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide 5000, Australia, e-mail, e-mail gregj@bgumail.bgu.ac.il, ²Mitrani Centre for Desert Ecology, Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990 Israel, e-mail Jeremy.Robertson@flinders.edu.au

Johnston, G.R. & Robertson, J.G.M. 1998. Facultative brood reduction in the Australian pelican Pelecanus conspicillatus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 256.

Most species of pelican exhibit obligate brood reduction by siblicide. We found that Australian Pelicans exhibit facultative brood reduction. Most clutches consisted of two eggs which hatch two days apart. The older (A) chick was thus larger than the younger (B) chick. This size difference facilitated sibling dominance and reduced survival among B chicks through siblicide. Both chicks survived in 38% of nests, and the second chick provided 'insurance' against loss of the first chick in 7% of nests. An experiment in which clutch size was manipulated (1, 2 and 3 eggs per nest) indicated that most productive clutches consisted of two eggs, despite high mortality of B chicks. A second experiment was conducted in which A chicks only, B chicks only, or no chicks were artificially fed. Neither A nor B chicks in different treatments differed in growth. But B chicks from nests in which A chicks were fed survived longer than B chicks in control nests. These results suggest that: (1) Sibling aggression is an important factor leading to brood reduction in Australian Pelicans. (2) The degree to which sibling aggression affects survival of B chicks depends on food availability to the A chick.

Key words: siblicide, seabird, pelecaniformes, egg insurance

Department of Biological Sciences, University of New England, Armidale, NSW-2351, Australia, e-mail gkaplan@metz.une.edu.au

Kaplan, G. 1998. Vocal mimicry and territoriality in the Australian Magpie Gymnorhina tibicen. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 256.

Vocal mimicry in song birds is an area of considerable interest but it has produced relatively few substantiated theories about its functions. Mimicry as embellishment of song, particularly for the male during the breeding season, is an explanation that appears to apply to some species, for instance the lyrebird Menura novaehollandiae and M. alberti. This paper will adopt Kroodsma’s suggestion that mimicry is related to territoriality and an aspect of song complexity. Australian magpies are fiercely territorial. Recordings of the vocalisations and mimicries of free-living Australian magpies have been collected throughout Australia and of handraised magpies (audio-examples will be given). The findings show that both the males and the females of the species mimic and they do so in and outside the breeding season. The findings further suggest that magpies mimic only those species which cohabit their territories. This may include dogs, horses, cats, human voices and other bird species. Unlike the lyrebird, there has been no record of magpies mimicking inanimate objects and sounds. Although magpies are diurnal birds, the study found that they also mimic nocturnal bird species, particularly those which are potential predators or competitors of magpies.

Key words: mimicry, song, territoriality

University of Stellenbosch, Private Bag X1, Matieland, South Africa, e-mail 9789367@narga.sun.ac.za

Kuiper, S.M. & Cherry, M.I. 1998. Determining levels of egg discrimination in two hosts of the Red-chested Cuckoo Cuculus solitarius. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 257.

The Red-chested Cuckoo Cuculus solitarius is one of twelve parasitic cuckoos that breed in southern Africa. It utilises several robin and thrush species as hosts, mimicking their eggs to varying degrees of accuracy. Three different egg morphs have been recorded for cuckoo eggs, none of which match that of the most commonly recorded host, the Cape Robin Cossypha caffra or another minor host, the Southern Olive Thrush Turdus olivaceus. Red-chested Cuckoo chicks evict any eggs or young present in the host nest and consequently recognition of cuckoo eggs should be critically important to the host. This study investigated levels of egg discrimination in the Cape Robin and the Olive Thrush by placing mimetic or non-mimetic model eggs in their nests. In addition, a stuffed cuckoo was presented in alternate trials in order to assess whether this enhanced discrimination by alerting the hosts.

Key words: brood parasitism, egg discrimination

University of Calgary, Calgary, Alberta T2N 1N4, Canada, e-mail mrlein@acs.ucalgary.ca

Lein, M.R. 1998. Rapid song change in a White-crowned Sparrow Zonotrichia leucophrys population at a dialect boundary. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 257.

Studies documenting shifts in boundaries separating bird populations with qualitatively different song patterns (dialects) are usually based on samples separated by several decades, providing little insight into the processes involved. Using data from 1984 to 1995, I examined change in song composition of a White-crowned Sparrow population in a sub-specific intergrade zone in Alberta, Canada. Populations within this zone have mixtures of males singing song patterns characteristic of nearby populations of the southern subspecies, oriantha, or of the northern subspecies, gambelii. In 1984, 33% of the study population were oriantha singers, 51% were gambelii singers, and 11% sang "hybrid" songs. Over the next decade the proportion of males singing oriantha song gradually increased and the proportion singing gambelii song decreased, the proportion of males singing hybrid songs increased, then decreased. By 1995, proportions of oriantha, gambelii, and hybrid songs were 95%, 5%, and 0%, respectively. Analyses of histories of 393 males and 480 nests showed no differences in survival or reproductive success among males singing different song patterns. In several years song pattern frequencies among first-time breeders (recruits) differed significantly from those of the previous year's population, or from those of returning breeders. This suggests that this rapid song change resulted from factors external to this population. Biased dispersal from more southerly oriantha populations is the most probable cause.

Key words: song, dialects, speciating, hybrid, reproduction

Université Paris sud, Orsay, France, e-mail Thierry.Lengagne@ibaic.u-psud.fr

Lengange, T., Aubin, T. Jouventin, P. & Lauga, J. 1998. Adaptation to acoustic communication in windy conditions: The case of the King Penguin Aptenodytes patagonicus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 257-258.

Atmospheric conditions have an important role in sound propagation and nevertheless have been poorly studied. In the King Penguins Aptenodytes patagonicus, both partners take part in hatching and rearing the chick. Mates can recognise each other in the hubbub of the colony using acoustic cues only. These, birds breed on the beaches at subantarctic islands where strong winds blow throughout the year. Studies were conducted to examine the degradation of signals due to wind and to determine how Penguins succeed in identifying individuals. We analysed the modification of the spectral composition of the ambient noise of the colony and the fluctuation in emergence of the display calls from the background noise in two opposite situations: with or without wind. According to the mathematical theory of communication, birds enhanced duration parameters to keep the same volume of information and thus to counteract the decrease in signal-to noise ratio. In windy situations, King Penguins enhanced the duration of the signal by adding syllables to the call. By measuring the total duration of nest relief periods, in which partners swop roles, under different wind conditions we examined the cost of wind to breeding penguins.

Key words: wind, acoustic communication, penguin

University of Bergen, Norway, e-mail Terje.Lislevand@zoo.uib.no

Lislevand, T. 1998. Incubation rhythm in Northern Lapwings Vanellus vanellus in relation to male-female and parent-offspring conflicts. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 258.

Incubation expose parents to energetic stress. Thus, conflicts exist both among mates and between parents and offspring. Here observations of Northern Lapwing, Vanellus vanellus, incubation rhythms are analysed in relation to such conflicts. Egg temperatures at the end of each recess were estimated using a mathematical model for egg cooling. Females incubated more than males, and male share of incubation varied significantly. Females adjusted their time off the nests in order to prevent the eggs from cooling below the physiological zero temperature (25°C). Estimated costs of rewarming was lower after male nest covering than when the nest was left uncovered. Duration and frequency of female recesses were negatively correlated, as were the nest attentiveness of each sex. Male incubation seemed to allow the females to prolong their recesses. Nest attentiveness was positively influenced by male incubation, without having any significant effects on hatching success. Precipitation influenced the males' incubation decisions and the recess durations, while ambient temperature did not. Male incubation did not appear to be crucial for maintaining embryonic development in the lapwings but might be motivated by a trade-off between mating attempts and needs for biparental care. In any case females should benefit energetically.

Key words: parental care, physiological zero temperature

Department of Biology, Dartmouth College, Hanover, NH 03755, USA, e-mail Peter.P.Marra@Dartmouth.edu

Marra, P.P. & Holmes, R.T. 1998. Mate fidelity in a migratory passerine warbler: Mate choice and the benefits of re-pairing. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 259.

From 1986 to 1995, 68% of 25 pairs of Black-throated Blue Warblers Dendroica caerulescens returning to breeding grounds in New Hampshire (USA) re-mated and 32% divorced. When individuals re-mated, both sexes returned to the same territory used in the previous season. In the case of divorcing males and when only males of a pair returned (n = 51), males returned to their former territories, whereas divorcing females and when only females of a pair returned (n = 24), they moved an average of 2-3 territories away. These results suggest that males exhibit strong site attachment, while females may be selecting either sites or mates. Reproductive success in the previous year did not account for the frequency of re-mating or divorce or for differences in dispersal distances. However, nestling quality, as indicated by body mass, tarsus length and wing length at fledging was significantly greater in both the initial and subsequent breeding seasons for individuals that re-mated compared to those that divorced. This suggests benefits to re-mating associated with nestling quality but not the number of nestlings fledged.

Key words: mate fidelity, site fidelity, reproductive benefits, passerine, mate choice

Centro de Zoologia Aplicada, Universidad Nacional de Cordoba, C.C. 122, Cordoba 5000, Argentina, e-mail martemo@com.uncor.edu

Martella, M.B., Navarro, J.L. & Bellis, L. 1998. New evidence on the mating system of Rhea americana. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 259-260.

The mating system of Greater Rheas has been described as polygynandry and promiscuity combined with male care. Individually marked rheas in a closed population were observed daily to record their aggressive encounters, escapes, copulations, egg laying and incubation behaviour. Four classes of adult males were distinguished: (1) non- reproductive males, (2) males that incubated only, (3) males that copulated and incubated, and (4) males that copulated only. These categories were related to the age of males (from younger to older, respectively), rather than to their aggressiveness. On the other hand, females were successively inseminated by the same or different males and then eventually laid their eggs in nests incubated by other males. Consecutive copulations may be a strategy by males to reduce sperm competition, and prevents female's identification of the paternity contribution. This generates behaviours that result in a mating system with a high degree of promiscuity. The mating system of rheas can be viewed as an extension of extrabond copulation behaviour with co-operative care, in which a bottleneck is imposed by the number of males that are ready for incubation and care of the chicks.

Key words: Argentina, behaviour, mating system, ratite, Rhea

Max-Planck-Inst. für Verhaltensphysiologie, Andechs and Vogelwarte Radolfzell, Von der Tann Str. 7, 82346 Andechs, Germany and Institute für Verhaltensbiologie, Freie Universität Berlin, e-mail mettke@erl.mpi-seewiesen.mpg.de

Mettke-Hofmann, C. 1998. Does breeding reduce exploratory behaviour? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 260.

To gather information about the environment is an essential part of the behavioural repertoire in animals. But there are great intraspecific differences in exploration. Some of them can be explained by differences in sex, age, or social rank. I investigated the influence of breeding- and non-breeding condition on exploratory behaviour. On two test days fourteen pairs of Red-rumped Parrots Psephotus haematonotus, eight in non-breeding phase and six in breeding phase, were confronted with three unknown objects in their familiar aviary for six hours each. Test days were separated by intervals of two days. Latencies between introduction of the objects and first contact as well as contact duration were taken as a measure of exploratory behaviour. Non-breeding birds showed significantly shorter latencies until first contact and touched more objects than birds in breeding phase. Significant differences in duration of exploration occurred on the first test day, but not on the second test day. The latter was due to a significant decrease in exploration in non-breeding birds as well as a slight increase in exploration in breeding birds. The results are discussed with respect to costs and benefits of exploration during these two phases.

Key words: parrots, object exploration, seasonal changes

Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eotvos University, Budapest, Hungary, e-mail Musil@ludens.elte.hu

Michl, G., Torok, J., Garamszegi, L.Zs. & Toth, L. 1998. Sex-dependent risk-taking strategies in the Collared Flycatcher under predatory threat. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 260.

There are different hypotheses concerning the amount of risk birds are ready to take for the sake of continuing parental care under predatory pressure. We tested three of them in a Central European population of the Collared Flycatcher Ficedula albicollis. According to the reproductive value of offspring hypothesis, the degree of risk-taking increases in consecutive stages of breeding (eggs, young nestlings, and old nestlings) and in this case the clutch is larger and/or the offspring are of better quality. According to the harm to offspring hypothesis, there is a decrease through the different stages of breeding in the parent's willingness to take risks, depending on the change in the vulnerability of eggs and/or offspring. The hypothesis of sharing in parental care predicts that female takes higher risks during the incubation period and in the brooding stage than the male does at any time, and also maintains that the female, soon after becoming a widow, takes significantly greater risks than the female participating in biparental care. The decisions made by male flycatchers were consistent with the prediction of the reproductive hypothesis and contradictory with the harm to offspring hypothesis whereas the decisions of females displayed an opposite tendency. All things considered, it was the sharing in parental care hypothesis whose predictions applied to the behaviour of both parents.

Key words: reproduction, Ficedula albicollis, predation, decision making, parental care

CNRS-CEBC, Villiers-en-Bois, France, e-mail breta@cebc.cnrs.fr

Mougeot, F., Arroyo, B. & Bretagnolle, V. 1998. Testing the 'mate-guarding' and 'frequent copulation' paternity assurance strategies in three semi-colonial raptors. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69:261.

Mate guarding and frequent copulation are alternative paternity guard strategies in birds. In raptors with extensive courtship feeding, males are expected to assure paternity through frequent copulations. We investigated experimentally the paternity guard strategies of three semi-colonial raptors, expected to suffer high risks of EPC (Red Kite Milvus milvus, Montagu’s Harrier Circus pygargus and Osprey Pandion haliaetus). We used a decoy, with or without a prey, for simulating a competitor male attending the breeding territory. We recorded, during experimental and control periods, male presence time, attacks toward decoy, copulations and prey deliveries. In all species, male presence time significantly increased during decoy presentations until laying was completed, suggesting that mate-guarding occurred despite the male food provisioning strategy. Decoy attack rates were also increased during fertile period and when we added a prey to the decoy. In the Red Kite, copulation rate was significantly higher during experiments, but only during the female fertile period. This was the only species where we found support for the sperm competition hypothesis. In the Osprey, copulation rate was lower during decoy presentation probably because males then brought less prey as they stayed for a longer time at nest. We compare these results to copulatory behaviour of other raptor species.

Key words: raptors, mate-guarding, sperm competition, coloniality

 

Australian National University, ACT, Australia, e-mail cel@dts.mg

Mulder, R.A. 1998. Plumage polymorphism and the mating system of Madagascar Paradise Flycatchers. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 261.

Male Madagascar Paradise-Flycatchers Terpsiphone mutata are polymorphic, and may exhibit either a rufous or a white-plumaged adult phenotype. Annual monitoring of colour-ringed individuals revealed that these adult phenotypes, once acquired, are stable, and may have a genetic basis. The two morphs may therefore represent an unusual example of evolutionarily stable alternative reproductive strategies. This study investigated whether the two male phenotypes are also behaviourally different, and whether females express mating preferences for either phenotype, by comparing reproductive success measured using molecular genetic techniques, provision of paternal care by each male phenotype, and relative annual percentage mortality for the two phenotypes.

Key words: polymorphism, mating system, ESS, Tersiphone mutata, female choice

Institut Verhaltensbiologie, Freie Universität, Haderslebener Str. 9, 12163 Berlin, Germany, e-mail rmundry@biologie.fu-berlin.de

Mundry, R. 1998. Song structure in hybrids of nightingale Luscinia megarhynchos and thrush nightingale L. luscinia. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 261-262.

Species-specific song features can be the result of learning but at the same time being genetically determined. Evidence on genetically encoded song information has been obtained from learning experiments in the laboratory where birds prefer to acquire species-specific over heterospecific patterns or develop species-typic song structures without ever hearing them. Another approach is the study of song features in hybrids, but only a few laboratory studies have addressed this issue (Güttinger 1979, Z. Tierpsychol. 49: 285 - 303; Mundinger 1995, Anim. Behav. 50: 1491 - 1511). In parts of the sympatric area of nightingale and thrush nightingale about 5% of all males are phenotypic hybrids. This provided a study of song structure in hybrids under natural conditions. Songs of the hybrids were compared with songs of nightingales and thrush nightingales recorded in the same area. Results suggest that song structure in hybrids is intermediate in some features (e.g. repertoire size), but resembles either parental species in other features like song and intersong interval duration. This indicates that, as with morphological traits, a highly variable behaviour like singing, that depends on learning, can show a hybrid structure. The study was supported by the BBAW

Key words: hybrids, song structure, Luscinia luscinia, Luscinia megarhynchos, learning

 

Institut für Verhaltensbiologie, Freie Universität Berlin, Haderslebener Str. 9,12163 Berlin, Germany, e-mail mnaguib@zedat.fu-berlin.de

Nadolph, K., Griessmann, B., Schlotter, G. & Naguib, M. 1998. Singing activity of male Blackcaps in relation to pairing status and distance to females. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 262.

One established function of bird song is to attract a mate. However, on a more proximate scale there is much less information about the influence of female presence on male singing activity. In this project we observed male singing activity in relation to distance from females before and after pairing in Blackcaps Sylvia atricapilla. In particular, we were interested if pairing state had an influence on singing activity of males in the close vicinity of a female. In order to establish a pair bond, males might sing more when close to a female before mating. After pairing, other mechanisms might be used to maintain the pair bond and so that male singing activity might be influenced less by female proximity. Male singing activity decreased after pairing. However, there was no evidence that the distance to females influenced male singing activity differently before and after pairing.

Key words: bioacoustics, behaviour, Sylvia atricappilla, bird song, breeding

1National Institute for Environmental Studies, Tsukuba 305-0053, Japan, e-mail hnagata@nies.go.jp, ²National University of Singapore, Kent Ridge, 119260 Singapore

Nagata, H. & Sodhi, N.S. 1998. Extra-pair paternity and paternity assurance behaviour in the Ochre-rumped Bunting. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 262.

The Ochre-rumped Bunting Emberiza yessoensis is a socially monogamous species. Sperm competition hypothesis predicts that males should guard their fertile females intensively or copulate with them frequently to secure their paternity. Intuitively, mate guarding should be relatively more intense in high breeding density areas. We studied copulation and mate guarding behaviour of the bunting in 1995 near Kamisu (central Japan). These buntings breed in Kamisu at relatively high density (4.5 pairs/ha). The proportion of extra-pair young were analysed from blood collected from adults and their broods by single locus method using two primers. We found that pair copulation rate was low (0.08/hr) and observed only two extra-pair copulations. Males perform intensive mate guarding by staying close to and by following their fertile females. Territorial intrusions by conspecific males, however, were not related to the female's fertility. We found extra-pair fertilisations in 45% of broods (n = 11), and 25% of young (n = 28) were not sired by their putative parents. Despite intensive mate guarding, males appeared to not effectively secure their paternity.

Key words: mate guarding, copulation, EPF, mating system, Emberiza yessoensis

FU-Berlin, Inst. für Verhaltensbiologie, Haderslebenerstr. 9, 12163 Berlin, Germany, e-mail mnaguib@zedat.fu-berlin.de

Naguib, M., Fichtel, C., & Todt, D. 1998. Timing of song onset during asymmetric vocal interactions in birds: Implications for additional receivers. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 263.

Territorial song birds are usually spaced within signalling distance of several conspecifics. This situation enables a bird to attend to vocal interactions of other conspecifics and potentially to extract information on their relative quality, strength or motivation. The consequences of such multi-dimensional spread of information have just begun to be incorporated in theories of communication. Particularly in bird song as a favoured system for studies on communication, the database is minimal. Here we will present results from a series of playback experiments with male territorial nightingales Luscinia megarhynchos as subjects. We simulated vocal interactions of two conspecifics in different roles near subject’s territorial boundaries using a dual-speaker design. The results show that subjects discriminated between the rival’s different roles by responding significantly more to the loudspeaker simulating the presumably more dominant intruder such as the one that was overlapping the songs of its counterpart and the leader during asymmetric alternating countersinging. These findings indicate that birds attend to other’s interactions and obtain and use information on their relative strength or quality. This behaviour might be beneficial for future interactions with any one of these conspecifics.

Key words: bird song, communication, nightingale, perception, social behaviour

Kate Oddie¹, Kate Lessells² & Christa Mateman²

1ICAPB, Edinburgh University, Edinburgh, UK, e-mail koddie@srv0.bio.ed.ac.uk, ²NIOO, Heteren, The Netherlands

Oddie, K.R., Lessells, C.M. & Mateman, A.C. 1998. Parental behaviour in relation to experimentally manipulated Great Tit brood sex ratio. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr.. Durban, University of Natal. Ostrich 69: 263.

Parents may adjust their level of investment in sons and daughters when fitness returns vary with offspring sex. We investigated whether great tit parents modified their levels of care to experimentally manipulated all-male, equal-sex and all-female broods, and whether any such variation differed between the male and female of the breeding pair. Using PCR amplification of a sex-linked marker we sexed 2 day old chicks and subsequently swapped them between nests to produce the three treatment groups. Provisioning behaviour (feeding rate, prey size, proportion of visits by the male, visit duration, and proportion of visits removing faecal sac) was measured for 8 to 9 and 11 to 12 day old broods. Data concerning effects on parental fitness through provisioning experimental broods were also analysed. There was no evidence that any measure of parental care differed with respect to brood sex ratio, or that the level of care varied between males and females of the pair. Thus we found no suggestion that parents adjusted investment in relation to brood sex ratio. This is one of the first experimental studies of the effect of offspring sex ratio and adult gender on parental care.

Key words: sex ratio, parental care, Great Tits, Parus major

 

Department of Animal Morphology, University of A. Mickiewicz, Poznan, Poland, e-mail osiejuk@hum.amu.edu.pl

Osiejuk, T.S. & Kuczynski, L. 1998. Song functions in European treecreepers, Certhia brachydactyla and C. familiaris: An experimental study. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 264.

The main question addressed is what are the functions of song in two European treecreepers. In 1997 on the study plot in western Poland 232 playback experiments in three series (pairing, egg laying = female fertile, and nestlings = female infertile) were performed. Eighteen variables describing song-rate, calls, reaction timing and distance to the stimulator were noted. The variables were log-transformed and after PCA reduced to 5 factors. FAC1 (song-rate and singing time after the playback) depended on breeding stage only (ANOVA, F_1,51 = 4.19, P < 0.05) and decreased with breeding progress. FAC2 (song-rate during the playback) was determined by the presence of other Certhia individuals (F_4,51 = 3.31, P < 0.02). FAC3 (time to the stimulated male reaction) was not influenced by any variable what confirm random distribution of experiments' location. Both FAC4 (distance to the stimulator) and FAC5 (calls frequency) depended on bird species (F_1,51 = 6.17, P < 0.02 and F_1,51 = 6.28, P < 0.1, respectively). C. brachydactyla reacted more strongly than C. familiaris. Certhia song functions both as a female attractant and rival male deterrent. Singing strategy depends on species, breeding stage and presence of rivals and is also connected with other behaviour variables such as calls and approaching to the rival.

Key words: Certhia, song functions, playback experiments, treecreepers, breeding, Certhia familiaris

Department of Vertebrate Zoology and General Ecology, Biological Faculty, Moscow State University, 199899, Russia, e mail nastya@ecol.msu.ru

Popovkina, A.B. 1998. Territoriality and aggressive behaviour of Ruddy Shelducks Tadorna ferruginea breeding in Askania-Nova Nature Reserve (Ukraine). In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 264.

Extremely high density of Ruddy Shelduck in Askania-Nova (up to 60 nesting pairs per 20 ha, nests located 10 to 50 m apart) is maintained by specific behavioural mechanisms. Ethological studies on individually marked birds were conducted in the reserve from 1987-1995. Highly aggressive in nature, Ruddy Shelducks in Askania-Nova expressed their aggressiveness towards conspecifics in more ritualised manner. At the beginning of the breeding season, most aggressive conflicts were confined to the nest sites. After onset of incubation, males shifted their territorial activities to the areas of future brood rearing, often located far from nests (up to 0.5 km away) and foraging sites (³ 1 km). During the 1st week after hatching, parents defended their young and their resting sites, and common foraging sites were used by families in turn. The number of conflicts significantly increased when ducklings were 8-40-days old, and the brood territories expanded and overlapped. Parents of older ducklings were less aggressive and almost no aggressive contacts were observed after fledging. Overlapping of brood territories may result in brood amalgamation, but aggressive contacts rather accompany this phenomenon than lead to it, as it is commonly accepted for other waterfowl species.

Key words: territoriality, aggressive behaviour, Ruddy Shelduck, Anatidae, breeding

Projet Terpsiphone, BP 42, Fort-Dauphin, Madagascar, e-mail cel@dts.mg

Ramiarison, R. & Mulder, R. 1998. Male plumage polymorphism and song in the Madagascar Paradise-Flycatcher. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 265.

Males but not females of the Madagascar Paradise-Flycatcher Terpsiphone mutata may express one of two different plumage phenotypes when adult, rufous or white. Once maturity is reached, phenotype never changes. As part of a study investigating the evolution of this sex-specific polymorphism and its role in the mating system of this species, we recorded and analysed the songs of individual males in our study population. Male paradise flycatchers are extremely vocal, especially during the breeding season. We were able to record the songs of about 40 males for analysis. The songs of individual males were found to be highly stereotyped, with only a single songtype recorded for each male, in recordings spanning a period of several months. However, no two individuals had identical songs. Songs of males from certain regions of the study site could be recognised by the incorporation of site-specific motifs, with local variation in male song structure resulting from different arrangements of local motifs. Preliminary analysis of song length suggested that the songs of rufous-plumaged males contained fewer elements than those of white-plumaged males. Song differences will be related to reproductive success of individuals, estimated using microsatellite analysis of paternity.

Key words: Terpsiphone mutata, song variability, plumage

Max-Planck -Institut für Verhaltensphysiologie, Andechs, Germany, e-mail vanthof@erl.mpi-seewiesen.mpg.de

Räß, M., Rödl, T., Canoine, V. & Van't Hof, T. 1998. Is singing in wintering Common Stonechats Saxicola torquata associated with territory density? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 265.

We observed migratory Common Stonechats during the non-breeding season at a Mediterranean and a desert site in Israel that are about 100 km apart. At both sites pairs of stonechats defended territories against conspecifics. However, males sang less at the desert site. Therefore, we compared endocrine and behavioural factors at the two sites to begin to understand the function and mechanism of singing during the non-breeding season. Levels of circulating testosterone were similar at the two sites and low compared to the levels during the breeding season. Interaction rates were higher in the Mediterranean as compared to the desert site. Interactions were predominantly intraspecific in the Mediterranean whereas intra- and interspecific interactions were similar in the desert. The density of territories was higher and territory size smaller at the Mediterranean site than in the desert. The results suggest that the singing during the non-breeding season is associated with density dependent territorial interactions and not directly associated with elevated plasma testosterone levels.

Key words: Common Stonechat, song, non-breeding season, testosterone

1Finnmark College, N 9500 Alta, Norway, e-mail helger@hifm.no, ²Department of Biology, University of Oslo, P.O. Box 1050, N-0316 Oslo, Norway

Rinden, H., Lampe, H. & Slagsvold, T. 1998. Song complexity does not indicate male parental abilities in the European Pied Flycatcher Ficedula hypoleuca. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 265-266.

Female European Pied Flycatchers prefer to mate with males having complex songs, but the benefits of this preference are not known. One potential benefit might be that males with complex songs contribute more to the feeding of the brood than males with simple songs. We tested this by recording weight change in 13 day old broods of 30 males during a period of 8 hours of enforced female absence. The males were matched in pairs according to brood size and, if necessary, nestlings were exchanged between broods to reduce initial differences in weight. Both males in each pair were treated simultaneously during the same day. The change in brood weight did not differ significantly between males with complex and simple songs (Wilcoxon matched-pairs signed-ranks test). We also recorded the feeding rate of 59 males in the presence of females, but neither the feeding rate of the males nor the males' relative contribution to the feeding correlated significantly with song complexity. Thus, we conclude that female Pied Flycatchers do not benefit in terms of increased feeding effort from males when preferring males with complex song.

Key words: sexual selection, female choice, male parental care, song, provisioning

 

University of Illinois, Department of Ecology, Ethology, and Evolution, 606 E. Healey St., Champaign, IL 61820, USA and Smithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Republic of Panama, e-mail songwren@pop.life.uiuc.edu

Robinson, T.R. 1998. Song Wren Cyphorhinus phaeocephalus family values: Female initiated divorce and step-family dynamics. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 266.

Factors motivating mate desertion (i.e. divorce) are poorly understood, especially in birds with long-term pair bonds. Divorce may occur for one of two reasons: (1) following a failed breeding attempt or (2) when one member of the pair finds a higher quality mate. Song Wren females actively initiated divorce even when no nearby males were available and frequently left after several successful breeding seasons. Females who re-paired with breeding males that had retained sons gained parental care for her offspring from both males. Females whose own older offspring were present gained no helping benefits for her younger offspring. Thus, females may abandon their current breeding situation in favour of gaining a stepson. Benefits of the strategy include both increased parental care for subsequent offspring, as well as potential higher genetic diversity if fathers and sons share paternity.

Key words: divorce, delayed dispersal, Panama, female choice, sexual selection

 

A70: The clapping arms-race: Why do some Clapper Larks not bother to play the game?

Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, South Africa, e-mail pryan@uctvms.uct.ac.za

Ryan, P.G. & Marshall, H. 1998. The clapping arms-race: Why do some Clapper Larks not bother to play the game? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 266.

Male Clapper Larks Mirafra apiata display by beating their wings together under the body to produce an audible clapping sound, and then whistle while parachuting to earth. Norberg suggested that wing clapping in the closely-related Flappet Lark M. rufocinnamomea is an honest signal of male fitness, because clapping occurs at more than twice the normal wing flap rate, incurring substantial energetic costs. Studies conducted in the Western Cape indicate that there are marked differences in both the vocal and clapping component of the display song between the nominate race and M. a. marjoriae. Within a population there are significant inter-individual differences in the rate and duration of clapping, which could provide cues for females to select mates, or for males to demonstrate superiority to other males. Both Western Cape subspecies wing clap at up to three times the normal flap rate, but other races from the east and interior of southern Africa do not accelerate their flap rate while clapping. A single recording from the Eastern Cape suggests that clapping rate may vary clinically. Why and how some populations of Clapper Larks appear to have opted out of the clapping arms race remains unclear. Experimental verification of the importance of clapping as a fitness cue is needed.

Key words: sexual selection, honest signalling, Alaudidae, geographical variation

 

Department of Biology, University of Natal, Durban 4041, South Africa, e-mail julian@biology.und.ac.za

Saunders, J.R. & Slotow, R. 1998. Evolution of song structure in southern African birds: A test of the Acoustic Adaptation Hypothesis. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 267.

Song is critical to territory defence, mate attraction, and both species and individual recognition. Because these factors affect individual fitness, characteristics that affect song transmission and degradation should exert a strong influence on the evolution of song attributes. Habitat structure is responsible for the degradation of acoustic signals as they are propagated through the natural environment and consequently the detectability, locatability, and readability of the signals are reduced. Habitat structure may exercise a selective force on vocal evolution such that song evolves to minimise the degradation of acoustic signals in the particular habitat in which a species has evolved. We conducted a comparative survey of the songs of 40 South African passerine species to test the generality of the AAH. The survey does not support the predictions of the AAH. The songs of South African passerine birds have not evolved to minimise degradation and attenuation caused by habitat structure.

Key words: environmental adaptation, habitat, passerines, attenuation, South Africa

Institut Verhaltensbiologie, Freie Universität, Haderslebenerstr.9, 12163 Berlin, Germany, e-mail Hultsch@Zedat.FU-Berlin.de

Schleuss, F. & Hultsch, H. 1998. Vocal ontogeny and the role of song rehearsal in nightingales. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 267.

The ontogeny of birdsong is explained as a process to attain sensorimotor control over vocalisations and to gradually adjust them to memorised song material acquired early in life. In a study of handraised nightingales Luscinia megarhynchos we investigated whether progression in vocal mastery would be reflected in the time scale of producing imitations of model songs that differed in structural complexity. Complexity was encoded in the number of element-types of master-songs to which males had been exposed. During vocal development, the ontogenetic age of imitations did not differ with respect to this variable, i.e. imitations of both 'simple' and 'complex ' models could be identified at the same time in early plastic song. However, assessment of ontogenetic progression revealed the following: (1) Imitations from simple models could be classified earlier as 'correct' (i.e. containing all element-types) than imitations from complex models. (2) For a certain period during development, the number of 'correct' versus imperfect renditions was negatively related to the models' complexity. (3) Syntactical errors were observed more frequently and for a longer time period for imitations from complex models. Our findings point to ontogenetic constraints in the reproduction of acquired song material and underline the role of rehearsal in vocal development. This study was supported by the BBAW.

Key words: bird song, nightingales, song development, song complexity, vocal rehearsal

Ethology, Institute for Evolutionary and Ecological Sciences, Leiden, The Netherlands, e-mail Selvino@Rulsfb.LeidenUniv.NL

Slabbekoorn, H., De Kort, S.R. & Ten Cate, C.J. 1998. Co-evolution in Streptopelia Doves, inter and intra specific aspects. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 267-268.

Vocalisations are of prime importance for species recognition in many bird species. Therefore vocalisations of closely related sympatrically occurring species are expected to be sufficiently different to provide cues for assortive interactions. We compared perch coos of all 16 species of Streptopelia doves, of which several live in sympatry. We examined whether and in which parameters the coos differed. Using playbacks in the Collared Dove S. decaocto, we tested the response level to variations in vocal parameters that discriminated best between species. All Streptopelia species produce a species-specific perch coo. Discriminant function analysis (DFA) based on ten acoustic measurements led to a 100% correct classification of individuals into species. Stepwise DFA showed that temporal features of the coos are the most discriminative between species. To examine whether these results have a biological meaning, we measured the response (flight activity) of territorial S. decaocto males to playback of manipulated and control coos. Alteration in the coo rhythm and removal of the first element led to a significant decrease in response level. Temporal features of vocalisations are important cues for species recognition in Streptopelia doves.

Key words: species recognition, species recognition, playback, Streptopelia doves

1School of Medicine, Indiana University, Bloomington, IN 47405, USA, e-mail suthers@indiana.edu, ²Department of Anatomy, University of Auckland School of Medicine, Auckland, New Zealand

Suthers, R.A., Goller, F. & Wild, J.M. 1998. Adult songbirds use sensory feedback during crystallised song to compensate for respiratory variables. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 268.

The crystallised song of most adult oscines is characterised by acoustic and motor stereotypy which does not require auditory feedback. Experiments described here on adult, male Northern Cardinals Cardinalis cardinalis provide the first evidence that the motor program for crystallised song can be modified by sensory feedback. The role of sensory feedback was tested by injecting very brief puffs of air into the cranial thoracic air sac, via a small cannula, during spontaneous song, while recording air sac pressure, the rate of airflow through the syrinx and electromyograms (EMG) of abdominal expiratory muscles. The resulting increase in air sac pressure early in a syllable is accompanied by a compensatory reduction in the amplitude of the expiratory muscle EMG during the remainder of that syllable. Inspiratory airflow during silent minibreaths between syllables is not regulated and the temporal pattern of trilled song is unaffected. Sensory feedback thus continues to play a role during adult song production in maintaining an appropriate syringeal pressure and airflow for phonation, despite unpredictable perturbations in respiratory pressure.

Key words: sensory feedback, bird song, motor control, electromyogram, respiration

Department of Environmental Science, Bessenyei Gyorgy College, Nyiregyhßza, P.O. Box 166, H-4400, Hungary, e-mail szept@szabinet.hu

Szép, T. 1998. The role of the different interests in the colony formation of Sand Martin Riparia riparia. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 268.

The question: why does a given individual joins to the colony? There is a need to integrate both the results of the traditional, colonial level studies which use an average individual cost and benefit approach and both the recent, individual level studies which investigate the individual differences in the mating success, EPC and brood parasitism. This study presents a new integrating approach, called the Different Interest Hypothesis, on the base of the data of intensive field studies made on sand martin colonies since 1992 in Hungary. Yearly, 700 to 1000 nests were investigated each week by endoscope in a 15 000 pairs population to study the breeding success and the occurrence of the brood parasitism and predation and its relation to the position in time and space of the given pairs in colonies. The length of the mate guarding at one colony during the entire pair formation period was video recorded and, the benefit and threat by EPC was investigated. The dominant, early breeding individuals have direct benefit by cuckoldry of the late arriving subdominants, by EPC and brood parasitism. The subdominant individuals join the colony for benefits that came from the closeness to dominants and others by which they can improve their mating and foraging possibilities.

Key words: colony, Sand Martin, EPC, brood parasitism, foraging

Laboratory of Animal Ecology, Faculty of Science, Rikkyo University, 12 building, Toshimaku, Tokyo 171, Japan, e-mail mtakagi@rikkyo.ac.jp

Takagi, M. 1998. Reproductive strategy of the Bull-headed Shrike Lanius bucephalus: An optimistic determination of clutch size. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 269.

Relationships between environmental factors that change seasonally and breeding performance of Bull-headed Shrikes were studied. The study was conducted during April-July, 1994 to 1996 at Ishikari, northern Japan. A large fluctuation of prey biomass occurred in 1994. The clutch size was largest in the middle of breeding season, while the number of fledglings was smallest during that period. Seasonal change of prey biomass corresponded to those of clutch size/number of fledglings. In 1995 and 1996, clutch size decreased steadily as the season progressed, and the number of fledglings decreased in parallel with clutch size. Clutch size of artificially fed pairs was larger than that of control pairs in 1995 when prey availability was relatively low. The most productive and largest clutch size corresponded to the modal clutch size. Even if brood reductions occurred by starvation, quality of fledglings in smaller broods was higher than that in larger broods. Thus, clutch size was not adjusted seasonally relative to prospective food for nestlings, but food availability during egg-producing period determined clutch size directly. It is adaptive to lay the largest clutch in response to amount of food during egg-producing period.

Key words: clutch size, supplemental feeding, seasonal change of breeding performance, Lanius bucephalus, Bull-headed Shrike

Insitute of Zoology and Limnology, University of Innsbruck, A-6020 Innsbruck, Austria, e-mail Leisler@vowa.mpi-seewiesen.mpg.de

Thaler, E. 1998. Sexual dimorphism in juvenile White-browed Tit-Warbler Leptopoecile sophiae and its relation to aggressiveness. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 269.

White-browed Tit-Warbler is a little known small passerine bird, living all the year in mountainous areas between 4-5000 m. a.b.l. and feeding exclusively on arthropods. Males and females differ strongly in their plumage: Males are purple-blue, females brownish-grey. Nothing was known about the breeding behaviour and the postembryonic development. The complete reproductive behaviour has now been observed for the first time in aviaries. Even the newly fledged juveniles have the same strong sexually dimorphic plumage as adults, a feature which does not occur in other passerine birds. Experimental manipulations revealed, that the exact "knowledge" of the sibling's sex may shorten or even avoid aggressive interactions between the young birds.

Key words: Leptopoecile sophiae, aggression, sexual dimorphism

 

1Institut Verhaltensbiologie, Freie Universität, Haderslebenerstr. 9, D-12163 Berlin, Germany, e-mail Todt@Zedat.FU-Berlin.de; ²Field Research Centre, Hatzeva, Israel; ³Tel Aviv University,Israel

Todt, D., Hultsch, H., Mundry, R., Naguib, M., Ostreiher, R., Schrader, L. & Zahavi, A. 1998. Experimental inquiry into the alarm call system of a co-operative breeder: The Arabian Babbler. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 269-270.

Alarm calls are excellent candidates for investigating how animals communicate a given risk and whether this is done by a system of referential signals. Our study addressed the use of alarm calls in Arabian Babblers Turdoides squamiceps. This oscines species develops an advanced group life, including co-operative breeding, and is well known from previous research. We inquired how babblers responded to either the presentation of different classes of predators, e. g. birds of prey, cats and snakes, or to the playback of selected acoustical signal patterns. The experiments concentrated on populations around Hatzeva, Israel where babblers are colour-banded and well known in terms of home ranges, social relationships within societies and genealogy. Analyses of the birds' behaviours revealed an interesting signal system: Instead of using distinct predator-related types of alarm patterns only, babblers preferred to produce distinct combinations of signal patterns when signalling a particular predation risk. The study was supported by a grant of the GIF

Key words: alarm calls, referential signalling, Turdoides squamiceps, predation

University of Hawaii, Department of Zoology, Honolulu, HI, USA, e-mail ewerf@zoogate.zoo.hawaii.edu

VanderWerf, E.A. 1998. Model presentations show subadult plumage of Elepaio functions in status signaling, not female mimicry. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 270.

The Elepaio Chasiempis sandwichensis is a monarch flycatcher endemic to the Hawaiian Islands, and has a two year delay in plumage maturation in both sexes. The second year plumage is juvenile-like, and the third year plumage is adult-like. I tested predictions of hypotheses for the evolution of delayed plumage maturation by presenting Elepaio with pairs of models (stuffed colour photocopies) representing second year, third year, and definitive adult plumages of both sexes in the breeding and nonbreeding seasons. Territorial adult male Elepaio attacked models of both second and third year males less aggressively than adult male models, but only during the breeding season. Aggression toward all models was similar and much lower in the nonbreeding season. Third year male models were attacked more than adult female models, but second year male models were not. These results support the hypothesis that delayed plumage maturation has evolved in Elepaio as an honest signal of subordinate social status that functions by reducing aggression from adults in competition for mates in the breeding season. Female mimicry and cryptic hypotheses are not supported because Elepaio distinguished subadult male models from those of adult females and males.

Key words: Elepaio, Hawaii, plumage, status signalling, model presentations

Department of Environmental Sciences, University of Milano, via Emanueli 15, 20126 Milano, Italy, e-mail rmassa@alpha.disat.unimi.it

Venuto, V., Bottoni, L. & Massa, R. 1998. Harmonic structure and species-specificity of food begging calls from four African parrots. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 271.

Food begging calls are highly stereotyped innate vocalisations whose structure is remarkably similar in quite different species, usually consisting of a series of homologous but not identical harmonic pulses. To understand: (1) How these so similar sounds may be species-specific, and (2) How they may be related to the adult sounds, we recorded and analysed, by means of the Canary software, food begging calls from four different species of African Poicephalus parrots, P. gulielmi, P. senegalus, P. meyeri, P. cryptoxanthus, from the birth to 30 days of age. In all species the call was structured in a series of harmonic pulses. The number was lowest in P. gulielmi, highest in P. meyeri. In all species, the number of harmonic pulses increased in the first ten days of age and then decreased. However, a clear-cut difference among the four species was maintained at all times. The same was true for the frequency range of the fundamental harmonic, although this increased steadily from the birth. By applying a cluster analysis to nine different sound parameters, P. gulielmi segregates neatly from all other species, bioacoustically confirming its usual classification in a different superspecies.

Key words: food begging call, Poicephalus, harmonic, pulse

Zoological Institute and Zoological Museum, University of Hamburg, Germany, e-mail wanker@zoologie.uni-hamburg.de

Wanker, R. 1998. Horizontal and vertical relationships during socialisation of Spectacled Parrotlets Forpus conspicillatus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 271-272.

Spectacled Parrrotlets live in a complex social system of individual relationships throughout their lives. In a long-term study on captive birds under semi-natural conditions, the development of the relationships of siblings (i. e. individuals growing up with nest mates) and singletons (i.e. individuals without nest mates) within a group of natural composition were studied from fledging up to 64 weeks post-fledging. The results show different dynamics in the development of relationships of siblings and singletons. Siblings show only a short period of vertical relationships with individuals of greater social status, i. e. their parents, and a long period of ample horizontal relationships to individuals with the same social status as themselves, i. e. their siblings. This might be due to a strong parent-offspring-conflict, as the parents deprive their young of affiliative interactions from the second day after fledging onwards. Singletons prolonged the period of vertical relationships to their parents. However, they also entered a long period of ample horizontal relationships by establishing a host sibling group with individuals of a like-aged sibling group. It is suggested that in case of the lack of one of these types of relationships, birds may compensate by enlarging the other.

Key words: Forpus conspicillatus, socialisation, relationships, siblings, singletons

 

Cornell University, Ithaca, New York, USA, e-mail phw2@cornell.edu

Wrege, P.H. & Emlen, S.T. 1998. Promiscuity by female Wattled Jacanas: A mechanism to manipulate males, not to obtain 'good genes'. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 272.

Jacana jacana (Jacanidae), is a neotropical shore bird with a polyandrous mating system and nearly complete male parental care. Females commonly produce eggs fertilised by males other than the care-giving male. Without exception, these extra-pair fertilisations are obtained by males simultaneously paired to the resident female, and the risk of raising unrelated young may be as high as 75% for males whose females were observed to mate promiscuously. Combining the analysis of detailed behavioural observations, DNA fingerprinting and a comparison of male morphological characters, we provide evidence against several alternate hypotheses for the benefits of promiscuity to females, including good genes hypotheses. We propose a "sex for influence" hypothesis and argue that females offer waiting males (those mates currently without eggs or small chicks) potential direct reproductive benefits as an incentive to retain them within the polyandrous group. Large harem sizes translate into significant reproductive benefits for females, but using promiscuity to obtain these benefits must be balanced against the cost of inducing rejection of all parental care by the cuckolded male.

Key words: polyandry, promiscuity, good-genes, cost-benefit, sex-for-influence

Institute of Biological Sciences, University of Tsukuba, Tsukuba, Japan, e-mail yama@sakura.cc.tsukuba.ac.jp

Yamaguchi, Y. 1998. Intraspecific nest parasitism and anti-parasite behaviour in the White-cheeked Starling Sturnus cineraceus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 272.

I studied intraspecific nest parasitism in the White-cheeked Starling, Sturnus cineraceus in 1992 and 1993. The population in this study consisted of 290 nests in which the clutches were completed. Sixty-one nests contained at least one parasitic egg and parasitism rates were about 20% in both years. Parasitic eggs hatched if they were laid during the laying and early incubation periods of their hosts, and a few of them fledged. Fledging success of parasitic eggs was not different from that of eggs in non-parasitised nests if parasitic eggs were laid during the host’s laying period. However, fledging success of all parasitic eggs was fewer than that of eggs in non-parasitised nests. Fledging success of parasitised nests was significantly lower than that of non-parasitised nests. Hatching success of parasitised nests was slightly higher than that of non-parasitised nests. Parasitism appeared to reduce the reproductive success of hosts. Hosts rejected parasitic eggs before the onset of laying, but they never rejected parasitic eggs laid after that period. The nest guarding level was low even during laying period of hosts. Thus, nest-guarding behaviour was not effective as an anti-parasite behaviour. Egg rejection and nest-guarding by White-cheeked Starling do not appear to be effective in reducing parasitism.

Key words: brood parasitism, White-cheeked Starling, breeding success, nest guarding, egg rejection

 

Jersey Wildlife Preservation Trust, Trinity, Jersey, JE3 5BP Channel Islands, Great Britain

Young, H.G. 1998. Water battles: The fighting techniques of Africa’s mallards. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 273.

Four members of the mallard group, genus Anas, are found in Africa. The migratory, Holarctic, Northern Mallard A. platyrhynchos winters in Africa and is sympatric in areas with two Afro-tropical species, the Black Duck A. sparsa and Yellow-billed duck A. undulata. A fourth species, the Madagascan, Meller’s Duck A. melleri was once considered to be an island isolate of the Northern Mallard. Captive populations of Northern Mallard, Yellow-billed and Meller’s Duck were studied extensively and videoed to compare reproductive behaviour. Data on the Black Duck has been taken from the literature. The males of all four species regularly fight with conspecifics and use species specific techniques. Northern Mallard and Yellow-billed Duck fight facing each other, pushing, Mallards peck at each others breast, Yellow-billeds grab the back of their opponents necks. Meller’s Duck chase after rivals tails. Black Ducks have carpal spurs and fight with open wings, attempting to hit each other whilst grasping the back of the neck. Close relatedness of these species is not mirrored in agonistic behaviour.

Key words: Anas, species, evolution, agonistic behaviour