Alekseeva, N.M. & Nikitin, V.P. 1998. Unique nesting behaviour of the Hooded Crow Corvus corone corvix in the anthropogenic landscape. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 315.

More, than 310 nests have been observed between 1992 and 1997. The Carrion Crows strive to nest near waste dumps and build nests at a height of eight to 25 m on all tree species present. If the high trees are absent crows build nests on electric pylons, scrub and antennae on houses. When high trees are present pylons are rarely used (16% of cases). The nests are built of artificial materials (wire, string, and paper) in 9% of cases. The crows nest in new nests (61% of cases) or previous year’s nests (39%) which have been hatched or abandoned. Eighty eight percent of broken nests are old (have been hatched or abandoned), 12% are new. 46% of nests hatch on the first year, the 66% of nests are broken on the second year of existence. The quantity of walking people and passing cars influence neither the density of hatched nests nor the height at which nests are built. Crows have adapted very well to the life in the anthropogenic landscape and have developed their preferences in the choice of nest site and nesting materials.

Key words: Corvidae, nesting, anthropogenic landscape, ecology

 

Anderson, B.A., Wildman, A.M. & Stickney, A.A. 1998. Identifying causes of nesting failures in Spectacled Eiders, arctic Alaska. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 315.

Spectacled Eider Somateria fischeri populations are declining across their breeding range in Alaska and Siberia, and this sea duck was listed as "threatened" in 1993. Poor nesting success (mean = 34%, 1993 to 1997) probably contributes to declines in arctic Alaska. Possible causes of nesting failures include egg predation and abandonment (poor attendance). We monitored eider nests with time-lapse cameras to identify predators, and monitored nest attendance by adding eggs with temperature sensors (thermistors) into nests. In 1995, we deployed two Super-8 movie cameras and one thermistored egg, but both nests were successful, so causes of failure were undetermined. In 1996, we deployed four thermistored eggs and two time-lapse video cameras. We recorded on video predators visiting nests, but both nests ultimately were successful. At nests monitored only with thermistored eggs (3 nests), we recorded one failed (eggs taken by an arctic fox Alopex lagopus) and two successful nests. Average nest temperature in all nests was 38 ° C, and incubation recesses averaged 0.5 per day. At failed nests, poor nest attendance did not contribute to failure. The two techniques, particularly when combined, effectively monitored nests. We will increase sampling effort in 1998, but preliminary results implicate predation as a principal cause of nesting failures.

Key words: eiders, population declines, nesting failures, predation, thermistors

 

Archawaranon, M. 1998. Hormonal correlate of seasonal reproduction in captive Thai Hill Mynas. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 315.

In seasonal breeding birds, the correlation between hormones and reproduction is strong. Thai Hill Mynas Gracula religiosa which breed from January to July showed typical differences of reproductive hormones between breeding and non-breeding season. Plasma levels of testosterone (T), oestradiol (E), follicle stimulating hormone (FSH), luteinizing hormone (LH), progesterone (P), and prolactin (PL) were measured for 12 months, using ELISA technique. From two groups of birds, 70 captive nonbreeders held in 6 outdoors aviaries, and 50 captive breeders held in 25 separate couple-cages. During breeding season T level in breeder males (3.65 ngml^-1) was significantly higher than in nonbreeder males (1.97 ngml^-1). E was virtually high in females especially in the breeders (499.81 pgml^-1). FSH, LH and P levels in breeders were higher than in nonbreeders, both during breeding and non-breeding seasons. These hormones increased during breeding time and decreased in non-breeding season. PL level did not show any difference between nonbreeders and breeders. Thai Hill Mynas which were kept in separate cages as pairs showed greater reproductive activity affected by hormones, especially during breeding season, than the ones which were kept as groups in aviaries.

Key words: Hill Mynas, hormones, testosterone, oestradiol, Gracula religiosa

 

Archbold Biological Station, Lake Placid, Florida, USA, e-mail rbowman@archbold-station.org

Bowman, R., Woolfenden, G.E. & Fitzpatrick, J.W. 1998. Timing of breeding and clutch size in the Florida Scrub-Jay Aphelocoma coerulescens. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 316.

Food supplementation experiments have provided weak evidence of a causal link between parental condition, clutch size and laying date. Effects of food supplementation may vary depending on the availability of natural food resources; however few such studies have measured food availability or lasted beyond one or two breeding seasons. We studied Florida Scrub-Jay over 4 years in natural habitats and in suburban habitats where supplemental food was available. Supplemented jays bred significantly earlier and the median date of laying the first clutch varied by only 4 days between years. Unsupplemented jays bred later and breeding date was more variable between years (range in median laying date = 27 days). Supplemented jays laid significantly larger clutches; however, food advanced laying date but did not directly effect clutch size. During years of high fledgling production (an indirect measure of natural food availability), differences in clutch size and the timing of breeding between sites were smaller than during years of low fledgling production. At both sites, clutch size and nesting success showed similar seasonal declines. In Florida Scrub-Jays, food availability appears to mediate timing of breeding, but seasonal variation in clutch size may be an adaptive response to decreasing offspring survival prospects.

Key words: clutch size, timing of breeding, supplemental food, corvids, resources

 

Brown, J.L. & Li, S.-H. 1998. The genetic mating system of the Mexican Jay. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 316.

Using microsatellite DNA typing, we studied parentage of nestlings of the Mexican Jay Aphelocoma ultramarina in Arizona, USA, 1991 to 1996. In this species males and females form pairs to build nests together, but separate after the breeding season. We found evidence of extra-pair fertilisation (EPF) in 66% of 52 broods (36% of 159 nestlings) for which all nestlings and at least the putative father had been sampled. All but two EPF fathers were in the same social group as the putative father. Thus, there were only two extra-group EPFs. This rate of intra-group EPFs is the highest known among communally breeding birds. No cases of conspecific brood parasitism were discovered, but in one case a pair appeared to have usurped the nest and eggs of another pair. This species lives in large, plural-breeding groups which are permanent residents on their territories and are often composed of multiple extended families. Proximate factors favouring EPFs are the occurrence of multiple adults of each sex in the same groups, the long persistence of siblings in their natal group, and the absence of enduring pair bonds.

Key words: microsatellite, jay, mating system, EPC, inbreed

 

Bucher, T.L., Vleck, C.M. & Chappell, M. 1998. Nest attendance patterns in Adélie Penguins Pygoscelis adeliae on Torgersen Island, Antarctica. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 317.

Well co-ordinated, biparental care of eggs and young chicks is essential for reproductive success in Adélie penguins because unattended eggs and chicks are subject to predation by skuas. Based upon published reports, Adélie penguins at Cape Bird on Ross Island (77° S, 166° E) show a fairly consistent pattern of nest attendance with three or four nest reliefs (mate change-overs) during incubation. We found a more variable pattern of attendance over four years in colonies on Torgersen Island, west of the Antarctic Peninsula (64° S, 64° W). Number of nest reliefs averaged from five to nine among years and ranged from three to 19 among nests within one year. First incubation bouts of males and females were shorter on Torgersen than on Ross Island. Incubation behaviour may vary with environmental heterogeneity. In Adélie Penguins the length of foraging trips during incubation may be related to the distance to open water and/or to the extent and type of ice near the colony, both of which will vary temporally and spatially.

Key words: penguin, behaviour, incubation, reproduction

 

Chang, F., Zheng, G., Zhou, X., Zhang, H. & Yang, J. 1998. Temminck's Tragopans are not monogamous. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 317.

The ecology of Temminck's Tragopan Tragopan temminckii was studied in the Wolong Nature Reserve, Sichuan province, China. The monogamous mating system of Temminck's Tragopan had been inferred from several observations of unmarked birds. Using radio tracking we concluded that birds mated polygamously, because of: (1) One male-several female groups existed in breeding season. (2) A gradation exists between two males if they are in one group at one time. (3) One male made mating displays to many females. (4) A male-female bond did not exist in incubation and brooding period. (5) Half of the mating groups are a paired male-female unit. If the territory is the exclusive part of home range, the ascendant male's territory is dynamic. Temminck's Tragopan and other pheasants did not show interspecific territorial behaviour.

Key words: mating system, breeding, reproduction, China, pheasant

 

Jia, C.-X., Zheng, G.-M., Zhou, X.-P. & Zhang, H.-M. 1998. The brooding behaviour of Blood Pheasant Ithaginis cruentus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 317.

From November 1994 to September 1995, the social organisation of Blood Pheasant Ithaginis cruentus was studied in Wolong Nature Reserve in Sichuan, China by radio tracking and field observations. Only females incubated. The rate of fertilisation of eggs was 85.1%, and 80.0% of eggs were hatched successfully (n = 20). The survival rate of chicks was 31.2%. The mortality of chicks was 62.5% during the first 10 days after hatched (n = 16). The chicks roosted in same trees with females from 15 days after hatching. The brooding frequency and duration of Blood Pheasant were influenced by both ambient conditions (such as the temperature and the precipitation) and the thermoregulatory capacity of chicks. The duration of brooding bouts lasted 8.00 ± 0.57 min (n = 92) regardless of the age of the chicks. The interval between two neighbouring brooding bouts was 13.6 ± 1.15 min. Brooding bouts tended to decrease in frequency and exceptions occurred on cold days as the chicks grew older. Brooding behaviour disappeared from the behavioural repertoire at about 40 days of age.

Key words: Blood Pheasant, brooding behaviour, breeding biology, China

 

Colbourne, R.M. 1998. Incubation behaviour and egg physiology of New Zealand's kiwi Apteryx spp. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 318.

Captive breeding of kiwi has been undertaken to enable natural populations to be supplemented through release of offspring back into the wild. However, despite being New Zealand's national bird, little is known of its reproductive behaviour, which affects the ability to hatch eggs successfully by artificial incubation. Considerable variation in incubation behaviour occurs between different kiwi taxa. Only male North Island Brown Kiwi Apteryx australis and Little Spotted Kiwi Apteryx owenii incubate eggs, whereas incubation is shared in the Okarito Brown Kiwi, the Great Spotted Kiwi Apteryx haastii, and the Tokoeka (Southern Brown Kiwi). Amongst Tokoeka, family group members can also assist with incubation. The egg can withstand long periods of cooling while the male feeds. The contribution to incubation by other family members means that kiwi usually have not expended too much effort through incubation, which enables them to have more than one clutch in a season. Kiwis regularly turn their eggs, an observation contradicting earlier findings. Experiments inducing water loss from fertile and infertile eggs show that it is not the embryo that regulates water loss, but a condition of the ambient humidity surrounding the egg. Adults may partially control the humidity by covering or uncovering the entrance of the nest with leaf material.

Key words: conservation, incubation, humidity, water loss, physiology

 

Cook, M.I. 1998. Competitive asymmetry in Black Guillemot broods. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 318.

In the Black Guillemot Cepphus grylle the potential degree of competitive asymmetry between chicks is extremely variable. This arises from a combination of differences between pairs in hatching patterns and in egg size. This provides an opportunity to examine the consequences for the chicks in terms of the level of sibling conflict, food distribution, growth rates and survival. Sibling interactions were monitored using a unique system of micro, infrared video cameras in conjunction with measurements of various parameters of reproductive success. Provisioning rate of parents was experimentally manipulated for short periods (by means of a scaring device) and sibling behaviour compared with controls. Under normal provisioning rates, low intensity attack frequency was greater among siblings of low competitive asymmetry, implying that dominance hierarchies take longer to establish in similarly matched competitors. In all nests, seniors attacked more often than juniors did. When relatively hungry, both rate and intensity of senior chick attacks increased above baseline values, effectively subduing the junior chick. Thus, high intensity aggression of the senior appears to be mediated by hunger, providing it with a feeding advantage over its sibling, but only in periods of reduced food intake.

Key words: hatching asynchrony, sibling aggression, food shortage, Black Guillemot

 

Daunt, F., Wanless, S. & Monaghan, P. 1998. Age specific reproductive performance in the European Shag. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 319.

Age specific reproductive performance was studied in a population of shags Phalacrocorax aristotelis on the Isle of May, Scotland, to separate the effects of age, breeding experience and individual quality. Five groups were examined and inter and intra-group comparisons carried out: (1) Two year olds breeding for the first time. (2) Three year olds breeding for the first time. (3) Three year olds with one breeding experience. (4) Four to 13 year olds with at least one breeding experience (survival rate constant) and (5) Over 14 with at least one breeding experience (survival rate now decreasing). A range of breeding parameters were measured and compared between groups, including egg production, hatching patterns, chick sex ratios, and breeding success. Parental foraging efficiency (measured from chick growth rates and adult diving efficiency and assessed using radio telemetry) and changes in parental body condition during breeding were also examined.

Key words: experience, sex ratio, breeding success, diving, Phalacrocorax aristotelis

 

Ewen, J.G. & Armstrong, D.P. 1998. Reproductive behaviour and extra-pair fertilisation in Stitchbirds. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 319.

Extra-pair copulations resulting in fertilisation are now recognised as an important mating strategy among many bird species. Often such behaviours are performed by paired males as part of mixed strategies, assumed to result in increased reproductive success. Stitchbirds have been described as having a highly variable, social, mating system, and are the only birds known to copulate in a face-to-face position. Reproductive anatomy suggests this species has intense sperm competition. This study describes social breeding relationships and mating tactics of Stitchbirds breeding in a strongly male biased population. The presence of sperm competition and relative success of varying reproductive behaviours are also investigated using DNA fingerprinting techniques. Nests during the 1995/96 and 1996/97 breeding seasons were sampled for parentage analysis. Thirty five percent of the scorable chicks were the result of extra-pair fertilisations. Males paired with females and also seeking extra-pair copulations accounted for 67% of these extra-pair fertilisations, leaving 33% to be the result of unpaired males gaining copulations. Results confirm intense sperm competition occurs and show that a mixture of unpaired and paired birds gain reproductive success from extra-pair copulations.

Key words: extra-pair copulation, minisatellite DNA, Notiomystis cincta

 

Fernie, K.J. & Bird, D.M. 1998. Carotenoids: Do they indicate individual-mate quality? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 319.

Carotenoids in plasma provide colouration of plumage and integument. We tested the hypothesis that brighter birds are superior quality individuals, and hence reproductive mates, by analysing plasma carotenoids in captive American Kestrels Falco sparverius. Serial blood samples were taken from yearling and adult kestrels over eight months (September 1996 to April 1997), then adults were paired according to carotenoid levels for comparisons between high-level pairs versus low-level pairs. Throughout the 1997 reproductive period (May to August), we measured plasma carotenoids and reproductive parameters involving courtship behaviour, egg size and mass, fertility, hatching success, and growth of young. During the 12-month period, carotenoids fluctuated significantly within individuals but independently of diet. Ranking of individuals according to carotenoid levels was consistent throughout the year, with high level kestrels consistently maintaining their ranking. Yearling females had significantly lower carotenoid levels than adult females, or adult and yearling males throughout the year. Initial analysis of reproductive parameters indicates high carotenoid females produced significantly heavier eggs when initially laid than low-level females, but egg size (i.e. width and length) and fertility were similar. Results to date are inconclusive in supporting the hypothesis of carotenoids indicating individual-mate quality.

Key words: carotenoids, mate quality, American Kestrel, Falco sparverius

 

Fessl, B., Hoi, H. & Dierkes, P. 1998. Helper strategies and extra pair young in the social monogamous Moustached Warbler Acrocephalus melanopogon. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 320.

The mating system of the Moustached Warbler was considered as socially monogamous. They breed early in the season and defend small territories in reed areas with low food supply. Therefore, biparental care seems to be necessary to successfully rear a brood. Observations at the nest identified additional males regularly visiting the nests and occasionally helping in parental care. From 25 nests blood samples of parents, chicks and eventual helper males were taken and DNA fingerprinting were done to access paternity. In over 50% of the nests extra-males were observed as helpers. They assisted at different levels of parental care, including incubation, chick feeding and defence of nestling. However, their parental effort is comparatively low. Preliminary results showed that those males actually had access to the females in their fertile period, as the extra-male sired 50 to 100% of the offspring. In one case of polygyny, the male lost his first mate and suffered cuckoldry for the whole clutch with the second female. So, although monogamy seems to be the rule, in some cases helpers are accepted at the nest which may be due to environmental constraints and helpers directly benefit by extra pair copulation.

Key words: helper, DNA-paternity, monogamy, Acrocephalus melanopogon, parental care

 

Gonzalez-Solis, J., Becker, P.H. & Wendeln, H. 1998. Mate fidelity and divorce in Common Terns Sterna hirundo. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 321.

The reasons and mechanisms for divorce have received increased attention since pair bond duration has been recognised to influence reproductive performance. The proliferation of hypotheses indicates that the problem is far from being resolved. The aim of this study is to understand why some pairs reunite while others divorce. From 1992 to 1998, Common Terns Sterna hirundo at a colony at Wilhelmshaven (Germany) fitted with transponders, were studied and their mates and reproductive performance were checked each year. Direct observation of courtship and copulatory behaviour of marked birds were performed. A multivariate model with the potential causes for divorce e.g. previous breeding success, arrival asynchrony between mates and body condition, was performed. Likewise, consequences of mate change for divorced and widowed birds were analysed separately for breeding status, nest site fidelity, subsequent breeding performance (i.e. clutch size, egg volume, hatching success and fledging success) and survival. Influence of age and sex was considered. Common Terns showed a high degree of social monogamy. No intra-seasonal divorce was observed. Results support the "musical chairs hypothesis" as a main cause of divorce between years. Among potential costs of mate change a deferred laying date and a decrease in nest site fidelity were identified. Cost derived from searching for a new mate rather than the benefits from familiarity with the previous mate itself seems to explain the mate fidelity.

Key words: Sterna hirundo, breeding biology, mate fidelity, divorce

 

Gowaty, P.A. 1998. Variation in female foraging success and extra-pair paternity in Eastern Bluebirds Sialia sialis. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 321.

The Female Constraint Hypothesis (FCH) posits that males attempt to constrain or influence female reproductive decisions by exploiting variation among females in their abilities to raise offspring without male help. The FCH predicts variation in the frequency of extra-pair paternity as a function of female dependence on males in raising offspring. We evaluate this prediction in populations differing in insect availability. A Georgia population suffers from insect food depletion due to competition from introduced fire ants. A nearby South Carolina population lacks competition with fire ants and enjoys relatively high insect availabilities. The time fertile females are off territory, the frequency and intensity of mate-guarding and male provisioning of females and offspring each vary in ways consistent with the FCH. The FCH predicts that within-populations females with highest foraging success have more extra-pair paternity in their broods than females with lower foraging success. The FCH predicts that extra-pair offspring are more common in populations with high prey availability than in populations with low prey availability. We used DNA markers to evaluate these predictions, and report variation among individuals and between populations consistent with FCH predictions.

Key words: extra-pair paternity, female constraint hypothesis, foraging skill, DNA, EPC

 

Halpern, B., Farkas, R., Tóth, Z., & Pásztor, L. 1998. Weight-loss during brooding in Great Tit Parus major. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 321.

Our study is based on data collected by a computer system, measuring nest boxes continuously with high-precision electronic balances. Data were collected and processed by The Wisitor 1.5, a software developed by Zoltán Tóth. We have analysed data from 11 nests, between 1993 and 1997. Nests were observed for 5 to 42 days. We followed all nests until fledging. Our analyses focus on the parents' morning and evening weight-profiles over the breeding period. The females' roosting weight-profiles consists of four separate stages that correlate with the different behavioural phases of breeding: egg laying, incubation, brooding and feeding. We found that in general females do not lose weight during incubation but they lose weight continuously for several days during the brooding phase then they maintain their weight during the feeding period. During brooding they lost 10% of their incubation weight on average. After brooding there were days when nestlings' growths was halted and at the same time at least one parent lost weight. This suggests that the parents do not possess reserves that would allow them to survive unfavourable conditions. This situation may be a consequence of the loss of reserves during brooding.

Key words: parental effort, Parus major, breeding, weight-loss, electronic balance

 

Hamao, S. 1998. Male reproductive tactics after the first mate's fertile period in the polygynous Black-Browed Reed-Warbler. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 322.

In polygynous bird species, males are expected to maximise their fitness by using either of two tactics after the fertile period of their first mates, i.e. attracting additional mates or performing extra-pair copulations. Black-Browed Reed-Warblers Acrocephalus bistrigiceps sing actively to attract females when they are solitary, but once they acquire females, they stop singing. Males exclusively guard their mates during their fertile period. I investigated which tactic of these males adopted during the postfertile period of their mates. Observations were made during 1994 to 1997 breeding seasons in a paddy field in Japan. During the postfertile period of their first mates, males showed two different behavioural patterns. In 44% of 32 cases, males actively sang as much time as before mating, but in 56% of the cases, males scarcely sang. Males who had resumed singing acquired secondary females significantly more often than males who had not resume singing. Nonresuming males had neighbours' fertile mates at significantly closer distances than resuming males. Three territorial intrusions by nonresuming males into the territories with fertile females were observed, but no intrusions by resuming males were observed. These results suggested that males decided to attract new mates or seek EPCs in response to availability of EPC partners around them.

Key words: extra-pair copulation, mate attraction, polygyny, song resumption, Acrocephalus bistrigiceps

University of Missouri, St. Louis, USA, e-mail hansen@jinx.umsl.edu

Hansen, E.S. 1998. Mortality and growth patterns of asynchronously hatching Arctic Tern Sterna paradisea chicks. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 322.

Based on published data, clutch size and breeding success of arctic terns is negatively correlated. Furthermore a relatively low breeding success is an invariable phenomenon according to a 11 year Icelandic study. Arctic tern chicks hatch asynchronously with about a day interval. To estimate the effects of hatching failure, the differential mortality of A, B and C chicks and the possible cause of death, examination of the growth and survival in 154 fenced nests were monitored for the first two weeks of the chicks life. The clutch size in the study colony was the highest reported for the species (2.44), about 50:50 one and two egg clutches, the one egg clutches appeared to be inexperienced pairs. Breeding success was generally very low. Hatching failure and egg predation (disappearance) accounted for about 5% of the losses. Strong effect of sibling competition was evident according to the growth and mortality patterns of the chicks. Accidental deaths occurred commingle among all chicks (ABC), supporting an insurance value of laying supernumerous young. The mortality rates differed between clutch sizes of two and three, being higher in the latter B and C chicks. Size independent and dependent mortality were both high, the former a collection of various reasons, the latter attributed to an intensive sibling food competition.

Key words: hatching asynchrony, Arctic Tern, Sterna paradisea, mortality and growth, sibling competition

Biological Sciences, Lancaster University, Lancaster UK, e-mail i.hartley@lancaster.ac.uk, ²Department of Zoology, Leicester University, Leicester UK

Hartley, I.R., Griffith, S., Wilson, K., Shepherd, M. & Burke, T. 1998. Nestling sex ratios in the polygynously breeding Corn Bunting. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 323.

We used a PCR-SSCP assay to sex 288 nestling Corn Buntings, Miliaria calandra, from 113 clutches studied between 1988 and 1990 in the Western Isles, Scotland. In each year the sex ratio was not statistically different from 1:1. Brood sex ratios did not deviate significantly from the binomial distribution when tested by robust randomisation tests. Although the effect was not strong, the proportion of males in broods declined as the breeding season progressed in 1989, although the opposite trend was observed in 1988 and 1990. Overall, we found no effect of year, timing of breeding, levels of polygyny, brood size or female size on brood sex ratios although several terms had significant interactions with year due to the effects of the data collected in 1989. Independently of brood size, the feeding rates of males, females or both combined did not vary in relation to brood sex ratios. However, the proportion of feeds provided by fathers was highest at male-biased broods when brood size was small (1 to 3 young) but at female-biased broods when brood size was large (4 to 5 young). We suggest that sons may be more valuable in small broods which have lower levels of sibling competition, whereas in large broods, daughters are of greater reproductive value.

Key words: sex ratios, polygyny, Miliara calandra, parental care, PCR

Department of Genetics and Zoological Laboratory, Haren, The Netherlands, e-mail d.h.heg@biol.rug.nl

Heg, D. & van Treuren, R. 1998. Female-female co-operation in polygynous Eurasian Oystercatchers. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 323.

The Eurasian Oystercatcher Haematopus ostralegus is described as a typically monogamous species, since removal experiments indicate that both parents are needed to raise the chicks to fledging. However, occasional polygyny has been reported several times. Here we describe how polygynous trios in oystercatchers arise and their reproductive consequences in a colour-marked population on the Wadden Sea island Schiermonnikoog. Besides the 'classical' form of polygyny (two female subterritories within the male territory), oystercatchers show a remarkable variant, accompanied by female-female co-operation, female-female copulations and joint nesting. The results show that females do not benefit from this co-operation, because: (1) These females are not related. (2) The trio fails to incubate the large joint clutch effectively, resulting in frequent hatching failures. Further, males might only benefit from polygyny if they can 'force' the females to co-operate, instead of remaining aggressive against each other.

Key words: reproduction, co-operation, copulation, polygyny, kinship, Haematopus ostralegus

Department of Zoology, Villavagen 9, S-752 36 Uppsala, Sweden, e-mail christer.hemborg@zoologi.uu.se

Hemborg, C. 1998. Breeding schedule and moult in the European Pied Flycatcher. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 323.

In temperate regions the two energetically costly processes, reproduction and moult, take place during a short favourable season. Several factors, such as daylength, hormones and social factors are known to be involved in the mechanisms controlling seasonal activities like reproduction and moult. In this experimental study the post-nuptial moult in the European Pied Flycatcher Ficedula hypoleuca was studied in relation to the breeding schedule. The breeding schedule was either delayed or advanced with about five days. This manipulation significantly affected female moult. Most delayed females suffered an overlap between reproduction and moult, while advanced females rarely had an overlap. The onset of moult in males was independent of the manipulation. The results from this study suggest that the onset of moult in females is strongly connected to their breeding schedule, while male moult seems to be more dependent on other external factors. A prolonged incubation period imposed fitness costs in terms of fewer fledglings and reduced fledging success of broods.

Key words: breeding schedule, moult, reproductive success, Ficedula hypoleuca

Department of Zoology, Villavagen 9, S-752 36 Uppsala, Sweden, e-mail christer.hemborg@zoologi.uu.se

Hemborg, C. 1998. Sexual differences in moult initiation: An experiment with timing of breeding in the European Pied Flycatcher. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: Z324.ZZ

In this experimental study, the post-nuptial moult in the European Pied Flycatcher Ficedula hypoleuca was studied in relation to the timing of the breeding cycle. By exchanging clutches with different laying dates the breeding cycle was either delayed or advanced. Most delayed females started to moult while feeding the nestlings, while advanced females rarely showed a moult-breeding overlap. Delayed females were also in a more advanced moult stage than females in control and advanced groups. Males were usually in a more advanced moult stage than females, but male moult did not differ between the experimental groups. The results from this study suggest that female European Pied Flycatchers have a more fixed schedule for reproduction and moult than males. Female moult initiation seemed to be dependent on their original breeding cycle, while the males initiated their moult when the brood reached a certain age. A change in the incubation period for females did not affect hatching success of eggs, but delayed females had a lower fledging success than control and advanced females. These findings have implications for understanding sexual differences in the mechanism controlling allocation of resources to reproduction and somatic investment, respectively.

Key words: control of moult, moult-breeding overlap, trade-off, flexibility, fitness

Percy FitzPatrick Institute of African Ornithology, University of Cape Town, South Africa, e-mail ohuyser@botzoo.uct.ac.za

Huyser, O.A.W. 1998. Co-operative breeding, chick growth and diet in Southern Skuas Catharacta antarctica at Bouvetøya Island. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 324.

Southern Skuas Catharacta antarctica breed at many sub-Antarctic and Antarctic island groups, and are unusual among seabirds in that, at many of these sites, they breed co-operatively. The significance of co-operative breeding in skuas is currently not well understood, with contradictory results from studies investigating short-term benefits e.g. enhanced chick growth or nestling survival for co-operative breeders. Thirty-six skua nests, including two trios (co-operative breeders), were marked and monitored every third day from December 1996 to February 1997 at Nyrøysa, Bouvetøya. Chicks reared by trios did not grow significantly faster than chicks reared by pairs, nor did single chicks grow faster than chicks from double broods. Chicks from earlier clutches did, however, grow faster than chicks from later (probably relaid) clutches. There was some variation across pairs and trios in diet, largely as a result of differences in territories occupied. Overall however, differences in diet and chick growth appeared to be unrelated. From December to mid-January adult Black-bellied Storm-Petrels Fregetta tropica were the most important prey item, and from mid-January to February Black-bellied Storm-Petrels and chicks of Southern Fulmars Fulmarus glacialoides.

Key words: co-operative breeding, diet, nestling survival, chick growth, Bouvetøya

1Beijing Normal University, Beijng 100875, China; ²Wolong Nature Reserve, Sichuan Province 623006, China

Jia, Ch.-X., Zheng G.-M., Zhou, X.-P. & Zhang H.-M. 1998. The social organization of Blood Pheasant Ithaginis cruentus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 324.

From November 1994 to September 1995, the social organisation of Blood Pheasant Ithaginis cruentus was studied in Wolong Nature Reserve in Sichuan China by radiotracking and field observations. The main results are as follows. In winter, Blood Pheasant lived in flocks and four flocks were located by tracing the tracks in the snow. The flock moved more frequently in February but less in January. The home range enlarged before the flocks were going to break up and overlapped with that of the neighbouring flock. During this period aggressive behaviour was observed. In the breeding season, four types of groups existed included subadult males, adult males whose mates were incubating and breeding pairs. During the incubating period the home range of both male and female extended far from the nest. The chicks were reared by both parents and together formed a family unit. When groups broke up and pairs formed, females dispersed and males did not. In breeding season, the home range of neighbour pairs overlapped and aggressive behaviour differed based on if individuals were from the same winter flock. Among individuals in the same winter flock aggressive behaviour did not occur and among individuals in different winter flocks aggressive behaviour occurred. We believe that the individuals from the same winter flock were close relatives.

Key words: Blood Pheasant, social organisation

1Waseda University, Tokyo, Japan, e-mail kikuchim@mn.waseda.ac.jp, ²Nagoya University, Aichi, Japan, Wako University, Tokyo, Japan

Kikuchi, M., Ishii, S., Kansaku, K., Shimada, K. & Imanishi, S. 1998. Changes in plasma levels of prolactin and luteinizing hormone throughout the breeding season in the shrike. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 325.

To elucidate the endocrine mechanism controlling the breeding behaviour in the free-living birds, we surveyed changes in plasma levels of luteinizing hormone (LH) and prolactin (PRL) throughout the breeding season in the Bull-headed Shrike Lanius bucephalus. Females and Males were caught by mist nets, blooded by puncture of a wing vein, and then released. LH and PRL in blood plasma were measured by radioimmunoassays. The level of LH was high in February and March, when shrikes were in the wintering area. Similarly high levels of LH were maintained through the periods of the nest building, laying and incubating. During the brooding period, the LH level declined slightly, but it was still high, being twice of the level in the post-breeding period. The level of PRL was low in the early breeding periods, i.e. the pre-breeding, nest-building and incubating periods. Then, it increased suddenly around the time of the hatch of chicks and declined thereafter gradually. Our conclusion is that the high prolactin level in the late breeding season may be related to the induction of the brooding behaviour in the shrike, and that such a high level of prolactin is not necessary for the incubation behaviour in this species. We also conclude that LH to plays an important role for an extended period from migration to egg-incubation.

Key words: Bull-headed Shrike, prolactin, luteinizing hormone, breeding, Lanius bucephalus

Department of Biology, Kyushu University, Fukuoka 812, Japan, e-mail hkofuscb@mbox.nc.kyushu-u.ac.jp

Kofuji, H. 1998. Geographical patterns of endocrine and reproductive cycles in Brown Dippers Cinclus pallasii. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 325.

Dippers are unique as passerines living in aquatic environments, and are among the earliest species to start breeding. In Japan, Brown Dippers Cinclus pallasii start laying from early April in Hokkaido (43° N), late February in Nara (34° N), and January in Kumamoto (32° N), respectively. The reproductive cycles were assessed by using the seasonal patterns of steroid hormone levels in faeces, in Nara (1998 to 1990) and Hokkaido (1994 to 1996). In Nara, the levels of testosterone (T-levels) in the faeces increased gradually from January and decreased in June. On the other hand, in Hokkaido, T-levels elevated rapidly in March and declined in June. Some environmental factors influencing the onset of breeding were considered. The peak of the biomass of aquatic insects larvae occurred in April both in Nara and Hokkaido. In Nara, nestlings were reared during the period of the highest food supply, while, in Hokkaido, nestlings were in nests during the period of the decline of food supply. The onset of breeding may be retarded by the snow cover affecting the availability of nest materials (moss) in Hokkaido. T-levels were possibly inhibited strongly until reproductive release.

Key words: reproductive cycles, geographical variations, food supply, testosterone levels, Japan

Laboratory of Ecology and Animal Systematics, Department of Biology, University of Turku, FIN-20014 Turku, Finland, e-mail EKORPI@utu.fi

Korpimäki, E. & Wiehn, J. 1998. Experimental evidence for food limitation on clutch size of kestrels. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 326.

Lack's hypothesis states that clutch size of altricial birds is limited by the number of young that parents can adequately feed during the nestling period. In addition, food limitation on clutch size would already act prior to and during the egg-laying periods. We food-supplemented nests of Finnish kestrels Falco tinnunculus in two experiments. Supplementary feeding prior to and during the egg-laying periods in 1986-88 did not advance the start of egg-laying and did not prevent the seasonal decline in clutch size of fed pairs, but they produced larger clutches than unfed control pairs. Supplemental food provided from hatching to fledging during 1992 to 1993 and 1995 increased the number of fledglings produced not only in years of low, but also high levels of main food (voles). Our kestrel population apparently is the only one, where food has been supplemented in separate studies both prior to and during the egg-laying, and during the nestling periods in several years that differed in the level of natural food supply. These two food addition experiments show that food is limiting clutch size of kestrels both during the egg-laying and nestling periods, and not only at low but also at high levels of natural food abundance.

Key words: reproduction, food supplementation, experiments, raptor, Falco tinnunculus

Percy FitzPatrick Institute, University of Cape Town, Rondebosch, 7701, e-mail gmalan@botzoo.uct.ac.za

Malan, G. 1998. The reproductive roles of polyandrous alpha and beta male Pale Chanting-Goshawks in co-operative-breeding. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 326.

The Pale Chanting-Goshawk breeds either in monogamous pairs or polyandrous trios. Since male breeders may be related, variation in fitness values with the different mating arrangements may promote co-operation and/or conflict among group members. The reproductive roles of Pale Chanting-Goshawks breeder groups were studied in the Little Karoo, South Africa, the only area where polyandrous trios are known to occur. The attendance of beta (subordinate) males to females increased significantly from the non-breeding to pre-laying period whereas the female attendance of alpha (dominant) males did not. During the pre-laying period, beta males copulated during a different time period and at a lower frequency than alpha males. However, during the nestling period, beta males provisioned prey to the female and nestlings at an equal rate to alpha and monogamous males. The genetic relationships of one polyandrous trio analysed (DNA fingerprinting) revealed that the males were full sibs but were not related to the female. If polyandrous males are not related, they produce less offspring equivalents than monogamous males, whereas as full sibs they produce more offspring equivalents. If alpha males and polyandrous females accommodate related beta males in the breeding group, their inclusive fitness may surpass that of monogamous breeders.

Key words: kin selection, Melierax canorus, Africa, inclusive fitness, co-operative breeding

Institute of Ecology and Evolution, Leninsky pr.33, 117071 Moscow, Russia

Matyukhin, A.V. & Matyukhin, G.A. 1998. Bluethroat Luscinia svecica (Turdidae) an abundant bird in the Moscow region. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 327.

In 1997 a marked population of Bluethroat was studied in the environs of Moscow. Two subspecies of Bluethroat breed in Moscow, Red-Spotted Bluethroat Luscinia svecica svecica (L. 1758) and White-Spotted Bluethroat Luscinia svecica cyanecula (Wolf 1910). First birds in Moscow were recorded in the middle of April. From this time to the first days of July intensive singing was recorded. Different males used the same territory for reclaim song. Complete laying (six eggs) was recorded on 15 to 16 May. First hatchlings were recorded on 28 to 29 May and first fledglings on 10 to 12 June. One polygynous male was recorded. Distance between both nests of polygynous male was 70 m. Two marked males with food near the same nest were recorded also. The feeding of fledglings was divided between both partners for the 7 to 10 days after nest departure. For Bluethroats second breeding attempt on the same territory was not recorded.

Key words: Luscinia svecica, breeding biology, Russia, polygyny

Cornell University, Ithaca, New York, USA, e-mail kjm2@cornell.edu

McGowan, K.J. 1998. A demographic description of the co-operatively breeding American Crow Corvus brachyrhynchos. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 328.

The American Crow is the only member of the genus Corvus known to be a regular co-operative breeder. Although it is a widespread and common bird in North America, little quantified information is available on any aspect of its life history. I studied a population of American Crows in New York state from 1988 to 1997, individually marking over 650 crows. I collected data on reproductive success, movements, and survival. Breeding pairs of crows held permanent territories, but often left them to forage and roost. Auxiliaries were present at 79% of nests; group size ranged up to 15. Most extra crows were helping their parents. Auxiliaries had no apparent effect on nesting success. Survival of young over the first year of life was high (48%), as was breeder survival (93% per year). Most crows did not achieve breeding status until 2 to 6+ years of age. Inheritance of at least part of the natal territory was an important avenue to breeding for males while females usually found breeding spots farther away. Territory ownership in American Crows may place constraints on the life history of the species that lead to co-operative breeding, despite the fact that they do not hold all-purpose territories.

Key words: reproduction, territory, demography, helping, survival

Department of Zoology, Downing Street, Cambridge CB2 3EJ, UK, e-mail sbm12@cus.cam.ac.uk

McRae, S.B. 1998. Group dynamics and reproductive success in the White-Browed Sparrow-Weaver determined using microsatellite DNA markers. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 328.

The co-operatively breeding White-browed Sparrow-Weaver (WBSW) Plocepasser mahali was studied on commercial farmland surrounding the Waterberg Plateau Park, Namibia, during the summers of 1995-98. WBSWs live in territorial multi-male and/or multi-female breeding groups. All group members participate in the maintenance of the group's roost nests and group choruses, but activities such as feeding nestlings are undertaken disproportionately by certain members. To test the hypothesis that variation in care activities is related to kinship, I determined parentage of young and estimated relatedness between the young and adult members of the group. Microsatellite DNA markers for WBSWs were cloned, characterised, and used to type each animal. The genetic analyses revealed that dominant females enjoyed full reproductive skew, consistent with predictions from previous studies. By contrast, dominant males within multi-male groups did not always monopolise paternity of group young. Observations of frequent group changes by males was supported by genetic data confirming that males tend to come from outside the group. The effects of drought on adult mortality, group dynamics, reproductive skew and fledgling sex ratios will be discussed.

Key words: reproductive skew, co-operative breeding, Plocepasser mahali, helping, microsatellite DNA

Institut für Vogelforschung "Vogelwarte Helgoland", An der Vogelwarte 21, D-26386 Wilhelmshaven, Germany, e-mail Mickstein@biologie.uni-oldenburg.de

Mickstein, S. & Becker, P.H. 1998. Habitat adapted nesting strategies of the Brown-Hooded Gull Larus maculipennis. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 328.

The Brown-Hooded Gull breeds in California Bulrush Scirpus californicus habitats. The gulls have different nesting strategies depending on habitat structure. In areas with dense bulrush they prefer to nest in the vegetation above the water surface. In more open areas most nests are floating, with or without connection to the plants. We investigated, if the most abundant nesting strategy is also the most successful. At two breeding colonies in Chile, Santo Domingo (39^°53' S, 73^°09' W) and Isla Teja (39^°50' S, 73^°16' W), the nesting strategies chosen, clutch size, and hatching success were recorded. In addition, at Santo Domingo, the fledging, and breeding success were recorded. The breeding pairs with the least common nesting strategy had the smallest clutch size, and lowest hatching, fledging, and breeding success. Pairs with the most common nesting strategy had the highest hatching success. We conclude, that the most successful individuals either choose a nesting strategy which is favourable with respect to the structure of their breeding habitat, or prefer breeding habitat structures which are suitable for their nesting strategy. This study was supported by the DAAD and the Volkswagen-Stiftung.

Key words: Larus maculipennis, Brown-Hooded Gull, nesting strategy, breeding habitat, adaptation

Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7700, South Africa, e-mail wdean@uctvms.uct.ac.za

Milton, S.J. & Dean, W.R.J. 1998. The use of green aromatic plants in Karoo bird nests. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 329.

Mossies Passer melanurus use a variety of aromatic green plants in their nests, and aromatic plants contributed substantially (26 to 64%) to the nest biomass. The most abundant plant genus in Mossie nests near Prince Albert in the Karoo was Helichrysum, although these plants were not locally abundant. All Helichrysum species are aromatic, and many are used as medicines, antiseptics or fumigants in Africa. Both Mossies and Grey-headed Sparrows Passer diffusus also bite off stems of an aromatic culinary herb Thymus vulgaris of European origin and take these to their nests. Other green aromatic plants collected from nests of Mossies in the Karoo include Dicoma capensis, Gnaphalium sp., Lasiopogon glomeratus, Leysera tenella and Pentzia pilulifera. The functional value of the use of green aromatic materials by southern African passerines remains to be investigated. We therefore intend to test Clark & Mason's hypothesis (Clark, L. & Mason, J.R., 1985. Oecologia 67:169-176) that volatile compounds in green plants improve nestling survival by reducing ectoparasites.

Key words: Passer, Helichrysum, thymus, Africa, ectoparasites

Department of Zoology, Graduate School of Science, Kyoto University, Kitasirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-01, Japan, e-mail mizutaku@ci.zool.kyoto-u.ac.jp

Mizuta, T. 1998. Dichromatism in male Madagascar Paradise-Flycatchers Terpsiphone mutata. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 329.

The dichromatism in male Madagascar Paradise-Flycatcher was studied in the northwestern Madagascar from 1994 to 1997. Breeding males were divided into four categories by means of the plumage colour and the length of tail feathers, i.e. white-coloured males with long tails (WL), rufous-coloured males with long tails (RL), rufous-coloured males with tails of medium length (RM) and rufous-coloured males with short tails (RS). RL and RM males have some white feathers on their primaries, secondaries, and upper wing coverts, whereas RS males do not possess such white feathers and look like females. I captured and marked a total of fifty-two (WL: 14, RL: 12, RM: 20, RS: 6) males in 1994, 1995 and 1996. Twenty-six marked males were resighted in the following year. Six WL males and six RL males did not change their plumage colour. Among eight RM males, three remained RM males, two changed to RL males and three changed to WL males. Six RS males changed to RM males. All the nestlings were rufous regardless of paternal colour. From these observations, I concluded that RS males were one year-old, and the next year they changed to RM males, and after that some individuals changed to RL males while others changed to WL males. This dichromatism in male Madagascar Paradise-Flycatcher is considered to be determined genetically.

Key words: dichromatism, Madagascar Paradise-Flycatcher, Madagascar, plumage, colour change

Murdoch University, Perth, Western Australia, e-mail lnichols@possum.murdoch.edu.au

Nicholson L.W., Nicholson A.B. & Bradley J.S. 1998. Automatic measurement of parental attendance in Wedge-tailed Shearwaters using an ultrasonic burrow monitoring system. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 330.

Procellariiform sea birds have young which grow slowly, but reach up to 150% of adult weight. This nestling obesity has been regarded as a response to chronic stochastic variability in food delivery at the level of the individual chick, as well as to temporal variation in feeding conditions for the colony. There are some difficulties involved in gathering data on parental attendance and meal size without possible disturbance of the breeding adults being studied. This poster describes a method using ultra-sonic technology which allows automatic measurement of parental attendance in a number of Wedge-tailed Shearwater Puffinus pacificus breeding burrows throughout the incubation and nestling period. Data collected by this method were calibrated over two consecutive breeding seasons, when chick weight and growth data were also collected. Each visitation to a burrow recorded by the monitoring system resulted in the chick being fed. Meal size was approximately 10% of chick body weight. 60% of chicks studied were fed nightly, with 40% of the total being fed twice in a night. This contrasts with some other shearwater species which are fed less frequently, but with meals of greater mass.

Key words: chick provisioning rates, meal size, Puffinus pacificus

ISP/ZMA, University of Amsterdam, Amsterdam, The Netherlands, e-mail birdlife@indo.net.id

Nijman, V. & Balen, S. 1998. Breeding biology of the Javan hawk-Eagle. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 330.

The breeding biology of the globally endangered Javan Hawk-Eagle Spizaetus bartelsi was studied in Gede-Pangrango N.P., West Java, Indonesia. Systematic observations on three nests were carried out in 1993, 1994, and 1997. Almost 150 hours of observation were made, covering different stages of the breeding cycle. Nesting trees were situated in submontane forest. Nests were built high up in forks on or away from the main trunk of tall trees; recorded cases involved Altingia excelsa or Quercus spp. Nests were large relative to the size of the bird and seemed to be traditional. In West Java breeding started from January until July, and presumably followed a biannual cycle. Clutches consisted of one single egg, and incubation lasted 47 ± 1 days. Incubation was predominantly done by the female, whereas prey during this period was brought to the female by the male. After hatching the female joined hunting. The male was rarely seen on the nest as copulation and prey transfer was done mainly on nearby trees. After fledging the juvenile stayed near the nest for at least two months. A prolonged post-fledging period followed, and the juvenile stayed with its parents for more than one year.

Key words: Javan Hawk-Eagle, breeding, Java, Indonesia, Spizaetus bartelsi

Department of Zoology, University of Queensland, Queensland 4072, Australia, e-mail VOlson@zoology.uq.edu.au

Olson, V.A. 1998. A new model for predicting the signals sent by carotenoid-based sexually-selected traits. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 331.

In a test of the Hamilton-Zuk and Immunocompetence Handicap hypotheses, the pre- and post-alternate moult colours of napes, throats, and bills of unmedicated male American Goldfinches Carduelis tristis, naturally infected with Isospora gryphoni (Apicomplexa, Eimeriidae), were scored and compared to those of males administered anti-coccidial drugs. The number of flying young reared by wild males of known colour and oocyst count was also observed. Post-moult bill colour in medicated birds was brighter than in unmedicated birds; nape and throat colours did not differ. Wild males with bright bills and low oocyst counts tended to rear more offspring than males with dull bills and high oocyst counts. Although the Hamilton-Zuk hypothesis appears not to explain sexual selection in American Goldfinches, the Immunocompetence Handicap hypothesis warrants testing. Based on these results, a new model that predicts the kinds of signals sent by male plumage and bill traits was proposed. This model should be tested through biochemical and comparative methods, as it may provide further evidence for the validity of a number of sexual selection hypotheses, particularly those mentioned above.

Key words: sexual, selection, carotenoids, parasites, Carduelis tristis, American Goldfinch

1Department of Regulation Biology, Faculty of Science, Saitama University, Urawa-shi, Saitama 338, Japan, rotsuka.cul@cul.tmd.ac.jp; ²College of Liberal Arts of Science, Tokyo Medical and Dental University, Ichikawa-shi, Chiba 272, Japan

Otsuka, R. & Wada, M. 1998. Circulating hormone levels in captive Humboldt Penguins in relation to reproduction and moulting. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 332.

Penguins are highly adapted to marine life. Their hydrodynamic efficiency depends on feathers which wear with age and need to be replaced regularly. During moulting, penguins cannot enter the sea to forage and are forced to fast. To better understand moulting in penguins, we collected plasma samples from 12 Humboldt Penguins kept in an open display pen in Japan throughout one year, and estimated circulating concentrations of testosterone, estradiol, thyroxine and triiodothyronine. We observed and recorded their reproductive activities and moulting. Humboldt Penguins Spheniscus humboldti maintained reproductive activity from January to December except during moulting. Most birds started moulting between the end of July and early August. Plasma concentrations of sex steroid hormones decreased and were lowest during moulting. On the other hand, plasma concentrations of thyroid hormones were low until early July and then elevated to high levels. These levels were maintained during moulting. Moulting were characterised by low concentrations of sex steroid hormones and high levels of circulating thyroid hormones.

Key words: penguin, hormone, reproduction, moult, Spheniscus humboldti

Department of Reproductive Biology, University of Agriculture, 2103, Godollo Pater K.u.1, Hungary

Péczely P. & Xuan D.D. 1998. Steriodal background of annual moulting pattern in Mallards. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 332.

The first year of the life cycle in Mallards Anas platyrhynchos is characterised by the juvenile, post-juvenile, post-nuptial and pre-nuptial moulting. During the four moulting processes, sexual steroid (testosterone (T), 17-B-oestradiol (E2) and progesterone (P4) plasma levels were analysed by RIA in male and female Mallards. The plasma levels of P4 show a typical bi-, or sometimes tri-phasic fluctuation. At the beginning of the change of plumage the P4 levels are high in the plasma and after a transitory decrease a second increase is observable during the period of intensive outgrowth of the new feathers, and frequently a high level is also typical at the end of moulting process. The plasma levels of E2 (mainly in the juvenile and post-juvenile moulting) increase with some phase shift, following the first P4 peak, and before the completion of the outgrowth of the new feathers, a second E2 peak is very frequent. The plasma levels of T are relatively low during the juvenile moulting, decrease continuously in the postnuptial moulting, but increase at the end of postjuvenile and prenuptial moulting in both sexes. Similarities in the pattern of the changes of sexual steroids have been compared in both male and female mallards during the four different moulting processes.

Key words: regulation of moulting, seasonality, sexual steroids, Anas platyrhynchos

1Changbai Shan Natural Reserve, Jilin 133613, China, e-mail sunyh@sun.midwest.co.cn; ²Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China

Piao, Zh.-J. & Sun, Y.-H. 1998. Reproductive success of Hazel Grouse at Changbai Mountain. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 332.

During 1986 to 1995, we studied the reproductive success of Hazel Grouse Bonasa bonasia at Changbai Mountain, Jilin Province, China. Radio-tracking data showed that the rate of reproductive success was 20.9% (n = 4), and the survival rate of chicks to the time of brood disintegration was 37.5% (n = 3). Field observations of broods during May to August indicated the chick numbers in broods decreased with their age in days. The relationship was described by the regression equation of y = 9.916 - 0.185x + 0.001X² (P < 0.0001). Hazel Grouse were counted every spring and autumn during 1986 to 1995, and the data analysed to determine the effects of weather during April to August on their reproductive success. The results indicated that the IRS (index of reproductive success) was correlated with weather during early chick period. The reproductive success was significantly negatively correlated with the precipitation and days of precipitation in June during the young chick period (P < 0.005, P < 0.025), suggesting that precipitation was adversely affecting chick survival. We found that the parasitism of the ticks Ixodes persulactus was one of the main factors causing death of the chicks.

Key words: Bonasa bonasia, reproductive success, weather effect

Department of Biology, University of Antwerp, U.I.A., Belgium, e-mail eens@uia.ua.ac.be

Pinxten, R., Eens, M. & De Ridder, E. 1998. Effects of testosterone on social dominance and mate attraction behaviour in captive male Common Starlings. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 333.

Most studies carried out on birds have shown that sexual and social behavioural repertoires in males are under strong control by testosterone. We studied the effects of testosterone on social dominance, nestbox occupation and mate attraction behaviour in captive male Common Starlings Sturnus vulgaris by castrating males or treating males with testosterone-implants and comparing castrated and/or treated males to controls. Males implanted with testosterone were dominant over castrated and normal males during encounters over food. These results contradict earlier studies claiming that castrated males should be dominant over intact males in starlings. However, after removal of the implants, castrated males tended have a significantly higher dominance-index than normal males, which seems to support the earlier studies. Control yearling males were dominant over castrated yearling males when tested in pairs, but this was not the case in adult males. Single castrated males placed in an aviary containing a nestbox did not occupy the nestbox, nor showed mate attraction behaviours and song behaviour after introduction of a female. These behaviours were however reinstated after the castrated males were treated with testosterone.

Key words: testosterone, starling, dominance, sexual selection, mate attraction, Sturnus vulgaris

Institute of Ecology, Avian Ecology Group, Dornburger Str. 159, D- 407743 Jena, Germany, bpe@rz.uni-jena.de

Quillfeldt, P., Schmoll, T. & Peter, H.-U. 1998. Chick growth and chick feeding in Wilson’s Storm-Petrel Oceanites oceanicus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 333.

Two different approaches have been used to investigate the feeding behaviour of procellariiform seabirds, one non-experimental and one experimental approach. We used both approaches to test: (1) Whether the feeding rate is determined by the parents or the chicks. (2) Whether feeding rate affected chick growth. (3) Whether adult body condition affected food delivery and (4) Whether feeding and growth were repeatable between years for the same nest or the same adult in Wilson's Storm-Petrel Oceanites oceanicus at King George Island, Antarctica. Chicks were repeatedly weighed and weight differences were corrected for metabolic loss to obtain an estimation of meal sizes. The peak mass and the body condition of the chick are significantly positively correlated with the average meal size and feeding frequency of individual chicks, with laying and hatching date, with wing growth rate and, to a lesser extent, with tarsus growth rate of the chicks. Parents of the five heaviest chicks were significantly heavier than parents of the five lightest chicks. These results support a parent-determined growth model, with laying date and feeding rate determining the growth rate and peak mass of the chicks.

Key words: Petrel, feeding, chick growth, provisioning, Procellariiformes

1Department of Conservation, P.O. Box 10420, Wellington, New Zealand, e-mail CRobertson@doc.govt.nz; ²ESR Environmental, P.O. Box 30547, Lower Hutt, New Zealand

Robertson, C.J.R. & Jones, P.D. 1998. Stress induced shell thinning in Northern Royal Albatross. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 331.

Northern Royal albatross Diomedea sanfordi breed at three small islands in the Chatham Islands and a small mainland colony at Taiaroa Head, New Zealand. Samples of eggshell were measured at the latter colony each year since 1969, while samples from the former were collected during the 1970s and 1990s. This albatross is a biennial breeder laying a single egg. No changes in eggshell thickness have occurred at Taiaroa Head 1969 to 1997. Mean thickness has declined in the Chathams by >20% between the 1970s and 1990s. There is no difference in thickness between failed eggs and those which hatch successfully. There is a difference at the Chathams between eggs laid in the first half of egg laying and the second half, with thickness declining as laying progresses and/or nesting density increases. Significant changes in nesting density occur where catastrophic nesting failure (at egg or guard stage) in one year, increases numbers attempting nesting the following season. Testing for contaminants revealed levels <10% of those found in North Pacific albatrosses having minimal shall thinning. Natural stress at the breeding site caused by degraded nesting habitat and increased nesting densities seems implicated.

Key words: Diomedea sanfordi, eggs, stress, contaminants, breeding

1University of California, Santa Barbara, CA, USA, e-mail rothstei@lifesci.ucsb.edu, ²Tel-Aviv University, Israel

Rothstein, S. I., Lotem, A., Shpirer, Y. & Zahavi, A. 1998. Why do smart crows accept cuckoo parasitism? A test of the mafia hypothesis. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 331.

To explain the enigmatic acceptance of brood parasitism by many host species, Zahavi proposed that parasites destroy parasitised nests if their eggs or young have been removed. This "Mafia Effect" may inflict a cost large enough to make it more profitable for a host to rear a parasite than to reject it. We tested the Mafia Hypothesis on Carrion Crows Corvus corone parasitised by Great Spotted Cuckoos Clamator glandarius in Israel. Parasitism was frequent (18.6% of 280 nests over three years) and costly as it reduced host fledging success by over 50%. Egg recognition experiments at 53 nests indicated that the crows never reject non-mimetic eggs. To test the basic premise of the Mafia Hypothesis, we simulated host egg rejection by removing cuckoo eggs from naturally parasitised nests. These manipulated nests were no more likely to fail than were naturally parasitised control nests from which we did not remove cuckoo eggs. Thus the Mafia Hypothesis cannot explain host acceptance in this system unlike what has been suggested for the same cuckoo in Spain. Crows may accept cuckoo eggs because of potential recognition errors as their eggs are sometimes variable or because the system is not at equilibrium and shows evolutionary lag.

Key words: brood parasitism, Corvus corone, Clamator glandarius, egg recognition, evolutionary lag

1Department of General Zoology, Eötvös Loránd University, 1088 Budapest Puskin u.3, ²Department of Reproductive Biology, University Agriculture 2103 Gödöllö Páter K.u.1, Hungary

Sass M., Péczely, P. & Mödlinger, P. 1998. Light and electronmicroscopic structure of the sperm cell of the Great Bustard. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 331.

Sperm cells of the Great Bustard are very thin and elongated structures (length: 7.3 m m). Their light microscopic structure is similar to the spermiums of Galliformes and Anseriformes. The acrosome (length: 0.7 m m) is filled with homogenous electron dense material and it has an elongated conical shape lying just before the nucleus. The plasma membrane holds fast to the outer acrosomal membrane. Sub-acrosomal material (perforatorium) is not developed; just a narrow subacrosomal space (filled with a small amount of filamentous material) separates the nuclear membrane from the acrosome. The dense, rod-like nucleus (1.8 m m long) contains a lot of deep invaginations filled by cytoplasmic vesicles and filaments. At the anterior end of the neck the nuclear envelope forms a short cone-like evagination. Just under this cone the two centrioles are embedded in a pericentriolar granule. The more caudal one corresponds to the basal body of axoneme. In the middle piece, helical, crescentic shaped mitochondria surround the axial filaments. Their inner membrane often disappears and parallel-organised membranes and small electron dense granules develop (parachristalline bodies). The tail part of the sperm cell shows a typical structural organisation.

Key words: Great Bustard, sperm cell structure, light microscopy, electron microscopy, Otis tarda

Depto. Zoologia, Instituto de Biologia, CCS, Universidade Federal do Rio de Janeiro, Ilha do Fundao, Rio de Janeiro, cep 21941-590, Brasil, e-mail vsalves@acd.ufrj.br

Soares, A.B.A., Alves, V.S., Couto, G.S. & Efe, M. 1998. Brown Noddy Anous stolidus breeding at the Abrolhos archipelago, Bahia State, Brazil. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 336.

Breeding biology of Brown Noddy Anous stolidus was studied in Abrolhos at archipelago, situated 70 km off the southeastern coast of Bahia state, Brazil, from March 1995 to August 1996. The species is migratory in the region, staying at the archipelago from the middle of February to the end of September, breeding mainly on Guarita island. The breeding population was estimated in 3926 individuals in 1995 and 4180 in 1996. Eighty-seven birds were banded in 1995, 66.7% of which returned to the island in the following year. Five birds of the breeding colony were banded as chicks before 1995, indicating that birds may return to their natal island, and breed from 22 months of age. Birds nested mainly on rocky substrate (74.4%) and their nests were rudimentary (84.6%). Clutch size is only one egg, incubated during 32.2 days in average. Nestlings show six different colour patterns, ranging from white to dark brown, dark colours prevailing. This study was supported by grants from CEMAVE (IBAMA), FUJB (UFRJ) and FAPERJ.

Key words: breeding biology, ecology, Brown Noddy, islands, conservation

Department of Ethology, University Bonn, Kirschallee 1, D-53115 Bonn, Germany, e-mail m.streif@uni-bonn.de

Streif, M. & Rasa, O.A.E. 1998. How do female Blackbirds Turdus merula optimise their long-term reproductive success? In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 336.

Costs and benefits of different reproductive strategies may vary for individual females during their lifetimes. In this study on Eurasian Blackbirds the strategies used by individual females were correlated with their long-term reproductive success. Blackbirds live for several (± 4) years and can make up to five breeding attempts per year. Females could therefore not only change strategy within but also between years. Since they not only choose their mates but also engage in extra-pair-copulations (EPC´s) there are a number of strategies they can adapt to maximise the number of offspring produced. The long-term strategies used by individually marked birds in a population of 35 to 38 breeding pairs were followed over a period of 4 years. Males in newly formed pairs showed higher levels of pre-ovulation mate guarding than in established pairs. Females in established pairs fed their nestlings less frequently than newly paired females. More intense mate-guarding and lower paternal investment in new vs. established pairs was correlated with the number of chicks per nest originating from EPCs. Which reproductive strategy a female followed was related to her age, duration of pairbond and also previous reproductive experience. For optimal lifetime reproductive success, females should change strategy after reproductive failure but continue with the same strategy after reproductive success.

Key words: Blackbirds, Turdus merula, reproduction

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

Toeroek, I.H. & Hockey, P. 1998. Variation in life-history traits of the European Bee-Eater Merops apiaster: A palearctic-afrotropical comparison. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 336.

Two highly disjunct migratory populations of European Bee-eaters Merops apiaster occur in the Old World, one breeding in the southwestern Palearctic (4 to 13 million birds) and one in the southwestern Afrotropics (20 000 birds). There is no evidence of interchange between the two populations. The first known breeding of European Bee-eaters in southern Africa was in 1886. This study compares aspects of the species breeding biology in France and South Africa. Both areas experience a Mediterranean climate. South African birds eat smaller prey, have longer incubation shifts and lower provisioning rates, hatching and fledging success than French birds. Despite the low reproductive output and high nestling mortality, there is no clutch reduction in South Africa. Some other birds of Palearctic origin breed in southern Africa, including White and Black Storks Ciconia ciconia/nigra and Booted Eagle Hieraaetus pennatus. The breeding performance of the latter does not differ between the Palearctic and Afrotropics, but both stork species have slightly smaller clutch and brood sizes in the Afrotropics. The relative performance of European Bee-eaters in the Afrotropics is very poor and the species colonisation of the region begs an explanation.

Key words: Meropidae, clutch reduction, Afrotropical birds, life-history traits, Merops apiaster

Behavioural Ecology Group, Eotvos University, Budapest, Hungary, e-mail yeti01@ludens.elte.hu

Torok, J., Tóth, L., Garamszegi, L. & Michl, G. 1998. Uni- and biparental care in the Collared Flycatcher Ficedula albicollis temm. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 337.

The Collared Flycatcher is a small, long-distance migrant hole-nester in Hungarian oak forests. Males are basically monogamous, but about 10% of them become polygynous in each year. In a four-year field study we measured the reproductive success of monogamous nests, as well as primary and secondary nests of polygynous males. Primary and secondary nests were close (mean 85 m) to each other and the difference in onset of breeding was five days. Secondary nests produced fewer and lighter fledglings than monogamous nests. As secondary nests received little male assistance during nestling care, we performed a field experiment to find out whether females can rear nestlings successfully alone. Although feeding activity of experimentally widowed females was higher than that of females in biparental care, reproductive output of single parent nests was significantly poorer than that of biparental nests. Another component of the costs of being widowed also appeared, i.e. weight loss of females during the nestling care was higher in single parent nests than in biparental nests.

Key words: Ficedula albicollis, polygyny, parental care, widowed female, reproductive success

1Population Biology Group, Department of Genetics, Eotvos University, Muzeum krt. 4/A, 1088 Budapest, Hungary, e-mail tothz@falco.elte.hu; ²Population Biology Group, Dept. Genetics, Eotvos University, Muzeum krt. 4/A, 1088 Budapest, Hungary; ³Theoretical Biology, Inst. of Evolutionary and Ecological Sciences, Leiden University, Kaiserstraat 63, 2311 GP Leiden, The Netherlands

Tóth, Z., Pásztor, L., Meelis, E. & Haccou, P. 1998. Individual differences in foraging and provisioning: Constraints, strategies, adaptations. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 337.

In the socially monogamous Great Tit Parus major both parents have high investment in parental care while there are marked differences in their related activities like brooding or nest defence. Analysing behaviour and efficiency on a visit to visit basis may contribute to the identification of the causes of such sex-related differences. Six nests were monitored by electronic balances from early nestling phase using our software package "The Wisitor". Male and female visits were identified by bodyweight. Having estimated the measurement error we excluded the unreliable measurements. We defined six acts based on the changes in bodyweight between two consecutive visits and on the changes in nest weight due to a visit. For example: significant self-feeding between two visits, visit with feeding and faeces removal. On a day when the female spent 7 hours brooding, her foraging bouts were shorter and her mean load weight was smaller. From foraging trips with significant self-feeding she returned with even smaller loads. The male, however, spent more time out and brought more food to the nestlings after self-feeding bouts. Results are significant at least at level 0.05. We assume, that the time constraint on the female imposed by brooding explains this resource allocation pattern. She takes the big prey items to the nest, eats the small ones and returns with any when her time is over. He searches for good patches and takes time to exploit them. We test this hypothesis by comparing brooding and non-brooding days in the measured nests.

Key words: parental care, foraging, behaviour, weighing, Parus major, Great Tit

Behavioral Ecology Group, Department of Systematic Zoology and Ecology, Eotvos Univ., Budapest, Hungary, e-mail ltoth@mme.zpok.hu

Tóth, L., Torok, J., Konczey, R. & Szollosi, M. 1998. Trade-offs in the reproduction of the Collared Flycatcher. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 338.

Fitness components (clutch size, number and condition of fledglings, number of recruits and survival of adults) were measured in a Hungarian population of Collared Flycatcher Ficedula albicollis. In addition, brood size manipulations were carried out during seven years. Data more than 1500 complete clutches (including natural and manipulated ones) were analysed. We did not find a trade-off between brood size and survival of adult and young birds in natural broods. However, the manipulation experiment provided some evidence for the validity of cost of reproduction hypothesis. Artificially enlarged broods produced lighter fledglings, which were less likely to return as recruits to the breeding population. It seems that cost of current reproduction did not affect in the survival of parents. Two other possible components of cost, the feeding frequency and the weight loss of parents were measured in natural and manipulated broods as well. Daily feeding frequency increased with increasing brood size showing a saturation curve, while weight loss of parents did not relate to feeding visits or brood size. In this Central European population of Collared Flycatcher the cost of current reproduction is reflected in poor fledgling condition resulting in fewer recruits as parents did not increase their investment in enlarged broods.

Key words: cost of reproduction, brood manipulation, feeding frequency, recruitment rate, Ficedula albicollis

Department of Avian Biology and Ecology, Adam Mickiewicz University, Fredry 10, 61-701 Poznan, Poland, e-mail ptasiek@hum.amu.edu.pl

Tryjanowski, P., KuŸniak, S., & Kuczyñski, L. 1998. Long-term changes of the Red-backed Shrike Lanius colurio eggs size. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 338.

The Red-backed Shrike has exhibited population decline over large parts of its range. Factors contributing to its decline include loss of breeding habitat, intensive agricultural practices, unfavourable climate, and decrease of food supplies. These factors could influence the egg’s size. From 1971 to 1996, 1122 eggs in 208 nests in SW Poland were measured using callipers. Using multiple regression method, the influence of the year, laying date and weather on egg volume (the means of clutches) was studied. None from the factors indicated has been shown to influence the mean length of eggs. Mean breadths were significantly correlated with clutch sizes (P = 0.0191). In the case of egg volume the year was the one significant factor: we recorded a negative trend (P =0.0106). Mean egg shape was significantly correlated with the clutch size (P= 0.0136). The decrease of the egg volume was small (3.6% during 26 years) but it is still a significant and constant trend. Assuming that egg measurements influence the nestling survival, even a minor decrease might cause a non-linear and significant decrease in breeding success. Probably the decrease of the egg volume mentioned above is a result of two factors: (1) Decrease of the females ability to produce larger eggs and/or (2) Systematic decrease of the accessible resources accompanied by the temporal and spatial increase of the homogeneity of their occurrence.

Key words: egg, nestling survival, breeding success

Seccion Zoologia-Vertebrados, Facultad de Ciencias, Tristán Narvaja 1674, Montevideo, C.P., 11200, Uruguay, e-mail ferreira@fcien.edu.uy

Vaz-Ferreira, R., Stagi, A., Loinaz, I. & Bianco, J. 1998. Functional characteristic and use of the nest of the Rufous Hornero Furnarius rufus rufus. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 338.

The mean weight of nests is 4.30 kg. The vertical diameter is 170 to 270 mm, the transverse diameter is 220 to 300 mm and the antero-posterior diameter is 170 to 240 cm. The nest structure adequately fills the functions of protection from predation and climatic extremes. In a recently constructed nest, the mechanical resistance to vertical pressure is greater than 100 kg/100 cm². The small diameter of the entrance and the communication between corridor and nest chamber impede predation by most birds and mammals but not by rats and snakes. Almost all nests are constructed on trees, posts and houses, where the frequency of predation is reduced. The nest material is not impermeable but on being saturated with rainwater the flow of water into the nest interior is stopped. The external surface of nests built on posts where there is all day exposure to the sun can reach temperatures of 43 ºC. Nest interiors never reach more than 40 ºC. Factors in thermal control are high specific heat of the material and the circulation of air. Each nest is used in only one breeding season. Thereafter the nest is abandoned and used by other birds. A possible epigamic role of nest building is discussed.

Key words: structure, protection, predators, climate, control

College of Arts and Sciences, Tokyo Medical and Dental University, Kohnodai, Ichikawa-shi, Chiba 272 Japan, e-mail wada@tmd.ac.jp

Wada, M. 1998. Reproductive strategies in the Japanese Bush-Warbler. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 339.

Japanese Bush-Warblers Cettia diphone are short-distance migrants; they winter in lowland bushes and breed at lowland hills to high mountains in bamboo thickets. They are very territorial and defend territories throughout the breeding season with conspicuous songs. They are polygynous and males do not participate in nest building, incubation and parental cares. To understand this unique breeding strategy, we captured birds which breed at University Forest, University of Tokyo, in Chichibu (alt. 1000 m) with Japanese mist nets by playback techniques and collected blood samples from March through October. We estimated plasma concentrations of testosterone (T) and corticosterone (B). Male birds arrived in the study site at the end of March and began to sing. They continued to sing till the end of August. Plasma concentrations of T were 1 ngml^-1 at arrival and increased to 2.5 ngml^-1 in May. The high concentrations were maintained by July and began to decrease. In August T was the lowest. In September, birds were present around the study site but did not respond to playback. Plasma concentrations of B showed a similar profile to those of T. Observations of six individual male birds indicated that most birds hold the same territories. In another group of birds captured at a wintering site in November and kept in an outdoor cage at Ichikawa, T changed as those in the wild birds but plasma B concentrations were lower than those of wild birds. The date indicates that extended secretion of T guarantees territory holding, which is rather stressful.

Key words: field study, warbler, breeding strategy, testosterone, corticosterone, Cettia diphone

 

Department of Biology, Nihon University School of Dentistry, Takasago 2-23-5, Tokyo 125, Japan, e-mail wakabayashi@dent.nihon-u.ac.jp

Wakabayashi, S. 1998. Effects of mammalian gonadotropic hormone on testicular activities in the Japanese Quail. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 339.

Under captivity, some avian species stop breeding. To solve this problem, we have devised a hormone administration method that can induce the ovulation and oviposition in female Japanese quail kept under short days. The present communication reports a recently devised method by us to activate testiclular spermatogenic and endocrine activities in male Japanese quail. Male Japanese quail of three weeks of age were purchased from a commercial dealer and divided into five groups. One group was kept under a photoperiodic regime of 14 hour light and 10 hour darkness and the other four groups under the regime of 8 hour light and 16 hour darkness. Two weeks after the purchase, three of the four short day groups were treated with the same dose of a pregnant mare serum gonadotropin (PMSG) preparation by implanting an osmotic pump (ALZET2002) containing the PMSG solution for two weeks and then with three different doses of the PMSG solution for two weeks. The last of the short day groups received no hormone treatment. By autopsy, we found that the testis and sperm duct were stimulated by the hormone treatment and these organs of the highest hormone dose group were as large as those of the long day males. By mating with laying hens, we found that one of 6 males of the 2nd highest dose group was fertile. We concluded that PMSG is effective to stimulate spermatogenic and endocrine activities of the testis in male Japanese quail.

Key words: gonadotropic hormone, male Japanese Quail, testis, breeding, sperm duct

1Department of Conservation, Wellington, New Zealand, e-mail murrayw@nzonline.ac.nz; ²Biological Sciences, University of Auckland, ³Department of Ecology, Massey University, New Zealand

Williams, M., Robins, J. & Lambert, D.M. 1998. Testing for evidence of natal philopatry in an island waterfowl using minisatellite DNA profiling. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 340.

We tested for evidence of natal philopatry within a population of Auckland Brown Teal Anas aucklandica inhabiting 56 ha Ewing Island by examining minisatellite DNA variation in groups of teal from three locations on the island. Group samples comprised members of contiguous territorial pairs. We would conclude natal philopatry was evident if birds within groups were more closely related to each other than to those in other groups, and if birds from nearest locations were more closely related to each other than to those at a more distant location. Probes used were 33.15, pv47-2 and 3'HVR. DNA profiles revealed high levels of bandsharing between individuals within each group (means 0.645 - 0.765) and similarly between individuals from different groups (group means 0.633 - 0.759). We cannot conclude natal philopatry is absent. Instead, we consider the high background relatedness will have masked any potential genetic structuring that would arise from philopatric behaviour. These high bandsharing indices are typical of island bird populations in New Zealand derived from few founders e.g. Chatham Islands Robin Petroica traversi (0.87), New Zealand Robin P. australis (0.65) and Campbell Island Teal Anas nesiotis (0.85).

Key words: philopatry, waterfowl, DNA fingerprinting, relatedness

Institut f. Pharmazeutische Biologie, Universitaet Heidelberg, INF 364, D-69120 Heidelberg, Germany, e-mail michael.wink@urz.uni-heidelberg.de

Wink, M., Dyrcz, A., Leisler, B. & Schulze-Hagen, K. 1998. Genetics of breeding systems in Arocephalus warblers. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 340.

Paternity of Acrocephalus warblers (A. paludicola, A. arundinaceus, A. palustris) was studied by DNA fingerprinting using oligonucleotides as multilocus probes or by microsatellite PCR. In A. paludicola a highly promiscuous breeding system was discovered. In some broods with six young, up to four or five fathers were involved. Some of these fathers appear to be genetically related (e.g. brothers). Males do not care for the young which are raised by the females alone. In A. arundinaceus a monogamous system was found, with occasional polygyny, whereas monogamy was the rule in A. palustris. Using nucleotide sequences of the mitochondrial cytochrome-b gene a phylogeny of Acrocephalus was reconstructed. This shows clearly that breeding systems evolved independently, that is within a monophyletic group monogamous, polygynous and promiscuous systems can coexist.

Key words: paternity, DNA fingerprinting, Acrocephalus, microsatellite PCR, breeding system

 

1Außenstation Braunschweig des Instituts für Vogelforschung "Vogelwarte Helgoland", Bauernstraße 14, D-38162 Cremlingen, Germany; ²Institut für Angewandte Zoologie, Rheinische Friedrich-Wilhelms-Universität, An der Immenburg 1, D-53121 Bonn, Germany, e-mail t.lubjuhn@uni-bonn.de

Winkel, W., Brün, J. & Lubjuhn, T. 1998. Reproductive success in monogamous and bigynous Pied Flycatchers Ficedula hypoleuca. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 340.

The Pied Flycatcher, a common hole-nesting passerine in northern and western Europe, has an unusual mating system. Beside monogamous breeding pairs, polyterritorial bigynous males are found regularly. The benefits of this reproductive strategy for males seem to be clear at first sight: Reproductive success should be much higher if a male is paired with two females. Here we present evidence that the benefits are not as high as would be estimated e.g. from the number of eggs laid by the females. We analysed parentage of more than 100 Pied Flycatcher broods from a population in Lingen (Germany) using DNA fingerprinting. Bigynous males were cuckolded significantly more often than monogamous males. This may be due to the fact that two females are not guarded as effectively as one female during the fertile period. The higher cuckoldry rate in bigynous males results in a loss of fitness greater than would be predicted assuming no extrapair copulations.

Key words: reproductive success, DNA fingerprinting, monogamy, bigyny, mating system

A. Koenig - Zoological Research Institute and Zoological Museum, Bonn, Germany, e-mail thomas_zuechner@compuserve.com

Zuechner, T. 1998. Reproductive patterns of two hummingbird species at high elevation in the Venezuelan Andes. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 69: 341.

Hummingbirds form a major avifaunal element at elevations above 3000 m. Some taxa, e.g. Oxypogon, Oreotrochilus Chalcostigma occur solely at these altitudes. To investigate possible adaptations of these high Andean species, I analysed the reproductive biology of two species in the Venezuelan Andes in 1995 and 1996: the Bearded Helmetcrest Oxypogon guerinii, a high montane specialist, and the Sparkling Violet-ear, Colibri coruscans, a species with a wider elevational range. Chicks of both species were weighed daily to calculate growth rates. Bearded Helmetcrests show significantly (P < 0.001) slower growth rates (K = 0.2327) than Violet-ears (K = 0.2999). Egg or chick predation was nearly absent (5.3% compared to some 80% in lowlands). Helmetcrests build large nests near running water totally protected from rain and sunlight compared to more exposed nest sites of Violet-ears (bushes and trees). The slower development and the use of cave-like nesting sites can be regarded as important adaptations to higher altitudes. Low ambient temperatures and the absence of predators may have resulted in slow growth in Oxypogon nestlings and in a high temporal/energetical investment in nest-building.

Key words: hummingbirds, reproduction, Oxypogon guerinii, Colibri coruscans, Venezuelan Andes