棕背黑头鸫繁殖习性初步观察

2008年和2009年的4～8月,在四川省雅江县帕姆岭对棕背黑头鸫Turdus kessleri的繁殖生态进行了初步观察.该鸟繁殖期在4月下旬至7月上旬,营树上巢,营巢树种为高山栎Quercus aquifolioides和鳞皮冷杉Abies squamata.窝卵数为2~3枚(n=7),平均卵重(7.96±0.03)g(n=8),卵长径(32.7±0.17)mm,短径(21.9±0.13)mm(n=13),雌雄共同孵卵,以雌性为主,孵化期为15~17 d(n=2),孵化率为83.3%(n=18).雌雄共同育雏,以雄性为主,雏鸟出飞后主要在巢周围的林下或灌从活动,这时亲鸟仍会对幼鸟喂食.在同一繁殖季对巢有重复利用的现象.     

BREEDING OF THE GREY WARBLER GERYGONE IGATA AT KAIKOURA, NEW ZEALAND

I studied the breeding of Grey Warblers Gerygone igata (Muscicapidae: Acanthizinae) in forest near Kaikoura, New Zealand, between 1976 and 1979. Only males sang and singing occurred all year. From late July to January pairs defended self-contained territories of 0·25–1·73 ha but they occupied larger home ranges when not breeding. Territorial adults were strictly sedentary all year. The average annual mortality of breeding adults was 18·5% and the predicted life-expectancy 4·9 years, which is remarkable in a bird weighing 6–7 g. The breeding season from first building to last fledging was six months long and it began early. Exceptionally, Grey Warblers may build and lay before the shortest day. As the season progressed warblers nested lower on average, both in absolute terms and relative to the tree nested in and canopy at the site. Warblers built in 7–27 days then delayed up to eight days before laying. Only females built and at no stage of breeding did males feed their mates. Both sexes fed the young. Grey Warblers laid for 15–16 weeks of the year and first clutches were laid asynchronously during 5–6 weeks. Eggs of a clutch appeared at two-day intervals and each egg weighed 1·5 g when fresh (23% of mean adult weight). Clutch size was nearly constant (mean 3·9, mode 4, range 3–5). The incubation period was 17–21 days (mean 19·5 days) and the nestling period 15–19 days (mean 17·2 days). On average the clutch hatched over 1·4 days, even though incubation commenced with the laying of the last egg. Nestlings reached maximum weight on Days 13–14 on average and then receded in weight by 4%, apparently through loss of water. All healthy nestlings exceeded mean adult weight during development by up to 39%. Nestlings from broods of two were at first lighter on average than those from larger broods, but in the second half of the nestling period twins were significantly the heaviest. Grey Warblers were fed for 28–35 days after fledging and they survived well while dependent on parents. Fledglings dispersed up to 3 km or more at independence and only 5% per annum joined the breeding population. Of nests that received eggs, 42% produced at least one fledgling. On average each breeding adult raised 2·0 fledglings per season. Of 265 eggs in 73 nests 70% hatched and 38% produced fledglings. Of 185 nestlings 54% fledged. Probably the main cause of mortality of eggs and nestlings was predation by introduced rodents and mustelids. Grey Warblers raise two small broods slowly during a long breeding season, rather than investing in one large quickly-reared brood. In New Zealand's mild climate the warbler's food supply may not decline severely in winter, and the population of warblers may remain so close to the limit set by food that extra for breeding is hard to obtain. Thus the breeding strategy may be adapted to a restricted food supply.     

Breeding biology of White‐rumped Tanagers in central Brazil

ABSTRACT White‐rumped Tanagers (Cypsnagra hirundinacea) are widely distributed in northern Brazil, Bolivia, and Paraguay, and are classified as vulnerable in the state of Paraná and as endangered in the state of São Paulo, Brazil. Little is currently known about their breeding biology. We studied the breeding behavior of White‐rumped Tanagers in the Cerrado (Neotropical savanna) in central Brazil from 2002 to 2007. The breeding period extended from mid‐August to mid‐December. Nests were cup‐shaped and located mainly in trees of the genus Kielmeyera at a mean height of 3.7 ± 0.3 m (SE). Clutch sizes varied from one to three eggs and the incubation period lasted an average of 16.0 ± 0.3 d. Incubation was by females only and started with the laying of the first egg. Mean nest attentiveness (percent time on nests by females) was 64 ± 0.08%. Nestlings were fed by males, females, and, when present, helpers. The mean rate of food delivery rate to nests was 5.2 ± 0.4 items/h, with rates similar for males (mean = 2.7 ± 0.3 items/h) and females (mean = 2.4 ± 0.3 items/h). The mean duration of the nestling period was 12.1 ± 0.5 d. Compared to many temperate species of tanagers, White‐rumped Tanagers in our study had relatively small clutches, low nest attentiveness, and long incubation periods. As with other tropical species, such characteristics might be due to food limitation or high rates of nest predation.     

Annual and seasonal reproductive trends in the Lesser Spotted Woodpecker Dendrocopos minor

Annual and seasonal variation in reproductive timing and performance were studied in a population of the Lesser Spotted Woodpecker Dendrocopos minor over 10 years in southern Sweden. The median laying date of the first egg varied by up to 17 days between years, being generally larger than the variation of laying dates within years. Neither clutch size, brood size in successful nests, fledging success in successful nests nor mean nestling weight differed significantly between years. There was no trend for mean clutch size to vary between early and late years. In spite of a more than threefold variation in population size, no reproductive variable demonstrated an apparent density-dependence. Within the season, clutch size declined steeply with increasing clutch initiation date, whereas fledging success and nesting success did not, leading to a trend in brood size almost identical to the trend in clutch size. The survival prospects of fledged young declined with increasing clutch initiation date, and it is argued that the clutch size laid is a strategic adjustment to laying date. Out of 124 breeding attempts, 34% did not produce fledged young. In 9% of the breeding attempts, pairs laid no eggs. At least 20% of the breeding attempts failed after egg-laying. The most common cause of breeding failure was loss of the breeding partner followed by nest abandonment (40% of the failures). Only 16–28% of the failures were due to predation on the nest. Most complete failures, and also partial losses from nests, occurred at the early breeding stages. It is argued that the early nestling phase may be a critical stage, which the woodpeckers adjust to coincide with the seasonal food peak, explaining the strikingly late breeding season compared with other non-migrant species.     

Breeding ecology of Red‐faced Cormorants in the Pribilof Islands,Alaska

ABSTRACT Red‐faced Cormorants (Phalacrocorax urile) are North Pacific endemics recognized as a vulnerable species, but little is known about their breeding ecology. We studied Red‐faced Cormorants on St. Paul Island, Alaska, from 1975 to 2009, with more detailed data collected in 2004 and 2005. Mean clutch sizes in 2004 (3.2 ± 0.8 [SD] eggs) and 2005 (3.1 ± 0.8 eggs) were similar to the long‐term average (2.9 ± 0.3 eggs from 1976 to 2009). The mean laying interval in 2004 and 2005 was 2.15 ± 0.80 d (N= 407), and the mean egg period (number of days between laying of an egg and hatching) was 31.1 ± 1.4 d (N= 158). Approximately 64 ± 17% of eggs hatched during the period from 1975 to 2009. The mean number of chicks per nest in 2004 and 2005 was 2.8 ± 0.8 (N= 232), and the mean number of fledglings per initiated nest in all years was 1.22 ± 0.52. Chicks fledged 46 to 66 d posthatching. In 2004 and 2005, the primary causes of egg loss were predation by Arctic foxes (Vulpes lagopus) and destruction of eggs and abandonment of nests due to storms. Starvation was the primary cause of nestling mortality in both years. Because chicks are dependent on parents to provide food for over 45 d, consistent near‐shore foraging opportunities must be available. From 1975 to 2009, Red‐faced Cormorants experienced only 1 yr of complete reproductive failure (1984). The consistent reproductive success of Red‐faced Cormorants suggests that conditions may be relatively stable for this species on St. Paul Island, or that the variability in their breeding ecology (e.g., phenology, clutch sizes, and incubation strategies) provides the flexibility needed to successfully fledge some chicks nearly every year.     

Nesting biology of Eastern Yellow Wagtails at Cape Romanzof, Alaska

ABSTRACT.   The nesting biology of the Eastern Yellow Wagtail ( Motacilla tschutschensis ) was studied at Cape Romanzof, Alaska, an arctic tundra site on the Bering Sea coast near the northeastern limit of the breeding distribution of the Yellow Wagtail ( Motacilla flava/citreola/tschutschensis ) species complex. Ninety-four nests were located and monitored from 1996 to 1999. Females built nests in 5–7 d, and nests were located on the ground. The mean clutch size was 5.6 eggs, and the mean incubation period was 11 d. Both adults incubated, and some males had a partial brood patch. The mean duration of the nestling period was 11.6 d, and both parents brooded and fed the young. Some adults began the complete prebasic molt (including primaries) while their young were still in the nest. Nestling development was similar to that reported for other Yellow Wagtails ( sensu lato ), but the breeding cycle and breeding season of Eastern Yellow Wagtails was compressed relative to Western Yellow Wagtails in Europe and to other passerine species breeding in western Alaska. Some breeding events overlapped, including initiation of egg laying before completion of nest building and initiation of adult molt while young were still in the nest. Clutch sizes were larger than reported for most European relatives. Clutch size generally fit with models predicting an increase of about one egg per 19 degrees of increased latitude. Rapid nest initiation, overlap of breeding cycle events, nest attendance (including incubation) by males, and slightly larger clutches appear to be adaptations to high-latitude breeding in this long-distance migrant.     

The breeding biology of the Chiffchaff Phylloscopus collybita in Britain: a comparison of an intensive study with records of the BTO Nest Record Scheme

Most known aspects of the breeding biology of the Chiffchaff come from studies carried out in Central Europe. This study documents aspects of its breeding biology in Britain by comparing data gathered during an intensive study in Wytham Woods (Oxford) from 1992 to 1994, and records from 1933 to 1993 held by the BTO's Nest Record Scheme. Comparison of these two data sets showed close similarities in parameters such as: (1) laying dates; (2) length of the breeding season; (3) nest site usage; (4) clutch size; (5) length of the nestling period; and (6) the relative importance of causes of nest failure. First clutches are laid in the second half of April, and early May, with second clutches in June. Nests are built close to the ground, usually in Bramble bushes (Rubus spp.). Average clutch size decreases from 6 to 4 eggs through the season. Incubation and nestling periods last 13–14 days. Nest losses are mainly due to predation, which accounted for approximately 75% of losses in both data sets, and the Weasel (Mustela nivalis) appears to be the main predator in Wytham Woods.     

Reproductive parameters in relation to food supply in the whiskered tern ( Chlidonias hybrida )

It is generally accepted that breeding terns are sensitive to food supply and that their reproductive effort could be substantially affected by the availability and access to resources. In this study we examined reproductive parameters in the whiskered tern Chlidonias hybrida in relation to food supply during the courtship feeding period (food brought by males to females) over a 2-year period (2004–2005). We also studied whether the condition of the nestlings [body condition index (BCI)] was related to a proxy of the reproductive investment of the adults (the clutch size) during a season of food shortage. Behavioural observations showed a decrease in the intensity of male courtship feeding between years (2004 > 2005), and a strong shift in the relative abundance of the two prey groups (invertebrates/fish; invertebrate prey dropped from 88.0 to 49.3%) brought by males. This change in food delivery rates did not result in a delay in laying, but there was a significant difference in mean clutch size between years (2.71 ± 0.49 eggs in 2004 and 2.05 ± 0.78 eggs in 2005) without any within-year variation in relation to the laying dates. The egg size (volume and length) was related to the year (2004 < 2005), suggesting a trade-off in the quantity and the quality of eggs between the two seasons. We also found no evidence that the investment in a large clutch affected nestling BCI in the course of the food shortage season. Since many pairs (about 60%) interrupted breeding during the incubation stage, we assumed that parents that succeeded in rearing nestlings in these conditions were probably ‘high-quality’ individuals. Our results therefore showed that whiskered terns are sensitive to the varying food conditions they experienced throughout the courtship period. The diversity of prey types could be a key factor in the reproductive investment of this tern species.     

SOME NOTES ON THE SPOTTED FOREST THRUSH

Brown, C. J., Riekert, B. R. &; Morsbach R. J. 1987. The breeding biology of the African Scops owl. Ostrich 58: 58–64.

The incubation and nestling periods of two pairs of African Scops Owls Otus senegalensis breeding in nesting boxes in the Daan Viljoen Game Park near Windhoek were studied. The incubation and nesting periods were about 22 ± 2 days and 25–28 days respectively. Incubation and brooding was by the female. The male provided all the food during the incubation period, but by the end of the nestling period 30% of food was brought by the female. The growth of the nestlings, parental behaviour and foraging methods are describe2 Of 100 food items brought to the nests, 93% (by number) consisted of arthropods, 6% reptiles and 1% small mammals.     

Breeding biology of Orange‐breasted (Harpactes oreskios) and Red‐headed (H. erythrocephalus) trogons in Khao Yai National Park,Thailand

ABSTRACT As tropical habitats continue to be cleared or degraded, obtaining basic information about the ecology of birds in intact habitats is essential for understanding their life histories. We studied the breeding biology of Orange‐breasted Trogons (Harpactes oreskios) and Red‐headed Trogons (H. erythrocephalus) in Khao Yai National Park in Thailand from 2003 to 2009. Nests were in excavated cavities in well‐rotted stumps or other tree parts. Mean cavity heights were 2.1 m (N= 19) for Orange‐breasted Trogons and 2.0 m (N= 49) for Red‐headed Trogons. Eggs were laid every other day. For Orange‐breasted Trogons, the mean clutch size was 2.4 ± 0.1 (SE) eggs (N= 17); incubation periods for two nests were 17 and 18 d, respectively, and the nestling period ranged from 12 to at least 14 d (N= 4). For Red‐headed Trogons, the mean clutch size was 2.6 ± 0.1 eggs (N= 48), the mean incubation period was 18 d (N= 9), and the mean nestling period was 13.4 d (N= 5). In both species, both males and females excavated nest sites, incubated eggs, and brooded and provisioned nestlings. Only females incubated and brooded at night, and males provisioned nestlings more than females. Breeding seasons lasted from January to March for Orange‐breasted Trogons, and from late February to July for Red‐headed Trogons. Mayfield estimates of nest success were 8% and 9% for Orange‐breasted and Red‐headed trogons, respectively. Unusual for cavity nesters, nest failure due to predation was high and nestling periods short. The low nesting success is typical of many other tropical species, but considerably lower than reported for some Neotropical trogons, possibly due to the unenclosed structure of the nests of these Asian trogons.     

BREEDING BIOLOGY OF THE BEARDED VULTURE IN SOUTHERN AFRICA,PART II: THE NESTLING PERIOD

Brown, C. J. 1990. Breeding biology of the Bearded Vulture in southern Africa, Part I: The nestling period. Ostrich 61: 24–32.

The nestling period of the Bearded Vulture Gypaetus barbatus in southern Africa was 124–128 days. The hatching interval between the normal two-egg. clutch was usually 3–6 days (range 2–9 days Only one nestling per clutch survived to the third day. Tittle sibling aggression and no infanticide took place, but the older nestling dominated the younger which obtained no food. For the first 40 days the nestling was closely brooded. The nest duties were evenly shared by both parents, but females brooded at night. Food was brought to the nest usually once or twice per day by both parents, and was stored behind the nest. During days 41–90 parental attendance steadily decreased. Dunng this stage the female spent more time in the nesting area (57%) and on the nest (91%) than the male. Towards the end of this stage the nestlin started to feed itself but preferred to be fed by a parent. From da 91 to first flight the nestling was left unattended and was visited by its parents only to provide food, which it fed from itself. All pars monitored (40 pair-years) attempted to breed every year. The breeding success (n = 18 pair-years) was 0,89 young fledged per pair per year.     

BREEDING BIOLOGY AND BEHAVIOUR OF THE QUAIL FINCH ORTYGOSPIZA ATRICOLUS

Summary

Nuttall, R.J. 1992. Breeding biology and behaviour of the Quail Finch Ortygospiza atricollis. Ostrich 63:110-117.

During a study of the breeding biology of the Quail Finch Ortygospiza atricollis, observations of nest-building, egg-laying, incubation and nestling periods, and nestling development in a grassland near Pietermaritzburg, South Africa were supplemented with observations of breeding behaviour in captivity. Mean clutch size was 4,5 and eggs were laid at intervals of approximately one day. Incubation began after the third or fourth egg was laid. An incubation period of 15–16 days and an estimated nestling period of 18–19 days was recorded. Incubation and brooding are shared by both sexes. Breeding success was low (26,7% ?28,6%), with most losses resulting from predation during either the egg-laying or incubation stages.     

The Social System of a Communal Breeder,the Bay-winged Cowbird Molothrus badius

Molothrus badius (bay-winged cowbird), an icterine blackbird with cooperative breeding, shares behavioural and ecological characteristics with other communal nesters: it is sedentary, has a high annual survival rate (76.2%) and a strong nest-site tenacity (mean breeding dispersal of 41.9 and 89.4 m for males and females). Behavioural data, including collective agonistic displays, suggest group territoriality. Before egg hatching most breeders occurred as single pairs showing territorial behaviour (82% of nests), and nesting was usually solitary (distances to nearest nests of 25–103 m). Most breeders were apparently monogamous, with a 2.5% incidence of extrapair copulations in the territory during clutch formation. During the nestling stage one to four helpers occurred at 95% of M. badius nests. Most helpers were 1–2 years old, but older breeding adults (mostly males) that failed to rear their own offspring helped at the end of the season. The number of helpers increased (up to 4) with nestling age. Helpers were also recruited during the postfledging period, and group size reached up to 10 adults at this stage. Helpers mobbed predators and brood parasites, and provided 35% of the nestling food. Provisioning rate was positively and significantly correlated with number of helpers, although age of nestlings was the best predictor of overall food delivery rate. The helping system was almost obligate and productivity comparisons between nests with/without helpers are not possible. Data suggest that helpers increased the breeding success per nest. The correlation between the provisioning rates of parents and helpers was negative but non-significant. In 18% of nests 3 to 4 individuals were present before the nestling period, including cases of apparently polyandrous trios and one case of joint nesting by two pairs. Within Brown 's (1987) categories of social organization M. badius is mainly group territorial with plural nesting. Habitat requirements of M. badius are wide and nest sites do not appear to limit breeding. Kinship plays a role in the social system, as 9 of 12 helpers marked as nestlings helped their parents.     

Life-history variation of a neotropical thrush challenges food limitation theory

Since David Lack first proposed that birds rear as many young as they can nourish, food limitation has been accepted as the primary explanation for variation in clutch size and other life-history traits in birds. The importance of food limitation in life-history variation, however, was recently questioned on theoretical grounds. Here, we show that clutch size differences between two populations of a neotropical thrush were contrary to expectations under Lack's food limitation hypothesis. Larger clutch sizes were found in a population with higher nestling starvation rate (i.e. greater food limitation). We experimentally equalized clutches between populations to verify this difference in food limitation. Our experiment confirmed greater food limitation in the population with larger mean clutch size. In addition, incubation bout length and nestling growth rate were also contrary to predictions of food limitation theory. Our results demonstrate the inability of food limitation to explain differences in several life-history traits: clutch size, incubation behaviour, parental feeding rate and nestling growth rate. These life-history traits were better explained by inter-population differences in nest predation rates. Food limitation may be less important to life history evolution in birds than suggested by traditional theory.     

Climate change and fitness components of a migratory bird breeding in the Mediterranean region

The increase in spring temperatures in temperate regions over the last two decades has led to an advancing spring phenology, and most resident birds have responded to it by advancing their onset of breeding. The pied flycatcher (Ficedula hypoleuca) is a long‐distance migrant bird with a relatively late onset of breeding with respect to both resident birds and spring phenology in Europe. In the present correlational study, we show that some fitness components of pied flycatchers are suffering from climate change in two of the southernmost European breeding populations. In both montane study areas, temperature during May increased between 1980 and 2000 and an advancement of oak leafing was detected by using the normalized difference vegetation index (NDVI) to assess tree phenology. This might result in an advancement of the peak in availability of caterpillars, the main prey during the nestling stage. Over the past 18 yr, the time of egg laying and clutch size of pied flycatchers were not affected by the increase in spring temperatures in these Mediterranean populations. However, this increase seems to have an adverse effect on the reproductive output of pied flycatchers over the same period. Our data suggest that the mismatch between the timing of peak food supply and nestling demand caused by recent climate change might result in a reduction of parental energy expenditure that is reflected in a reduction of nestling growth and survival of fledged young in our study populations. The data seem to indicate that the breeding season has not shifted and it is the environment that has shifted away from the timing of the pied flycatcher breeding season. Mediterranean pied flycatchers were not able to advance their onset of breeding, probably, because they are constrained by their late arrival date and their restricted high altitude breeding habitat selection near the southern border of their range.     

Sooty Falcon Falco concolor reproduction and population dynamics on the islands in the Sea of Oman

Knowledge of demographic parameters affecting population dynamics is critical to the formulation of effective conservation strategies. Sooty Falcon Falco concolor is a little‐studied, Near‐threatened species; estimates of global population size and trend for this species are uncertain. They lay eggs during mid‐summer and sometimes nest in colonies. This unusual breeding ecology suggests that demographic parameters driving their population growth rate may differ from those of most other falcons. We studied Sooty Falcon reproduction at breeding aggregations on Fahal Island and the Daymaniyat islands in the Sea of Oman during 2007–2014, modelled population growth and identified important life history parameters using elasticity analysis. The mean (± se) clutch and brood size was 2.83 ± 0.06 and 2.11 ± 0.07, respectively. Overall, 11.7% of nests failed between the egg and nestling stages, and the failure rate differed significantly between Fahal and the Daymaniyats, and across years. The mean proportion of eggs that hatched annually was 0.66 ± 0.02, and broods were significantly smaller on the Daymaniyats than on Fahal. Falcons on Fahal Island had a higher rate of hatching, a higher rate of nests that produced at least one chick, and produced more chicks per nest than on the Daymaniyats. We suggest that Fahal's proximity to the mainland gives breeding Sooty Falcons access to a more plentiful and stable source of food, especially during the period between arrival from the wintering grounds and the onset of the autumn migration of prey birds, resulting in the better reproductive rates for falcons on Fahal Island, relative to those on the Daymaniyat Islands. The annual asymptotic population growth rate (λ) was 0.87 (95% confidence interval (CI) 0.75–0.99), suggesting a declining population, although Sooty Falcons enjoyed a slightly higher population growth rate on Fahal than on the Daymaniyats. Because our study population is on the edge of the breeding range and is isolated from other breeding areas, measures to improve reproductive success of Sooty Falcons breeding on the islands in the Sea of Oman could be important for conservation of Sooty Falcons in Oman.     

Multiple responses to increasing spring temperatures in the breeding cycle of blue and great tits (Cyanistes caeruleus,Parus major)

Many bird species start laying their eggs earlier in response to increasing spring temperatures, but the causes of variation between and within species have not been fully explained. Moreover, synchronization of the nestling period with the food supply not only depends on first‐egg dates but also on additional reproductive parameters including laying interruptions, incubation time and nestling growth rate. We studied the breeding cycle of two sympatric and closely related species, the blue tit Cyanistes caeruleus and the great tit Parus major in a rich oak‐beech forest, and found that both advanced their mean first‐egg dates by 11–12 days over the last three decades. In addition, the time from first egg to fledging has shortened by 2–3 days, through a decrease in laying interruptions, incubation time (not statistically significant) and nestling development time. This decrease is correlated with a gradual increase of temperatures during laying, suggesting a major effect of the reduction in laying interruptions. In both species, the occurrence of second clutches has strongly decreased over time. As a consequence, the average time of fledging (all broods combined) has advanced by 15.4 and 18.6 days for blue and great tits, respectively, and variance in fledging dates has decreased by 70–75%. Indirect estimates of the food peak suggest that both species have maintained synchronization with the food supply. We found consistent selection for large clutch size, early laying and short nest time (laying to fledging), but no consistent changes in selection over time. Analyses of within‐individual variation show that most of the change can be explained by individual plasticity in laying date, fledging date and nest time. This study highlights the importance of studying all components of the reproductive cycle, including second clutches, in order to assess how natural populations respond to climate change.     

Breeding ecology of the Fulmar Fulmarus glacialis and the Kittiwake Rissa tridactyla in high-arctic northeastern Greenland, 1993

The breeding ecology of the Fulmar Fulmarus glacialis and the Kittiwake Rissa tridactyla in the high Arctic was studied in relation to the occurrence of the northeast water polynya in northeasternmost Greenland (80̀N). Mean laying dates were 31 May in the Fulmar and 18 June in the Kittiwake; the total nesting season for the Fulmar just matched the time window of the polynya opening period. Fulmar colony attendance fluctuated within a period of 11.6 days because of variation in nonbreeding prospectors but showed no clear diurnal variation. Fulmar incubation shifts, on average, lasted 6.1 days (range 1–13 days), which is significantly longer than elsewhere, and the average chick-guard period of 10.9 days (range 1–17 days) was significantly shorter than in other studies. Egg neglect occurred in 18% of Fulmar nests or 0.7% of nests per day. Overall breeding success (chicks fledged per egg laid) was 0.56 in the Fulmar and 0.67 in the Kittiwake; the latter produced 1.4 young per active nest or 1.2 per completed nest. Mean Kittiwake clutch size was 2.03; larger clutches were laid early. Nest site characteristics (presumably reflecting nest predation risk) and breeding behaviour affected breeding success. in the Fulmar, hatching success was negatively correlated with laying date and the proportion of egg neglect, while overall breeding success was correlated negatively with distance to nearest neighbouring site and positively with the length of the chick-guard period. Kittiwake breeding success was negatively correlated with laying date. Using seabirds as indicators of marine food supply, breeding success in both species suggested moderate to good food supply in the northeast water polynya in 1993, although at least in the Fulmar the high reproductive output appeared partly maintained by behavioural buffering; long incubation shifts, egg neglect and short chick-guard periods were symptoms of foraging constraints.     

2. COLLETOPTERA AFFINIS AT THE NEST

Research into the effect of environmental variables on reproductive success of tropical raptors is often constrained by the lack of information on breeding biology. We provide the first detailed information of the breeding biology and nestling development of the Grasshopper Buzzard Butastur rufipennis, an Afrotropical migratory raptor threatened by extensive land transformation in its breeding range. Breeding coincided with the transition from the dry to the wet season. The mean incubation period was 30 d and mean fledging period 36 d. The breeding period was characterised by rapid establishment of territories and short post-fledging dependency periods related to the onset of migration shortly after breeding. Growth rate of body mass, tarsus, wing and primary feathers were similar between sexes, which showed significant but moderate body mass dimorphism at fledging (♂85–90% of ♀). Second hatchlings were smaller in body mass and structural dimensions compared to similarly-aged first hatchlings and singles of the same sex. Survival of second hatchlings was related to body mass ratio with first hatchlings, whereas brood reduction occurred through food competition and siblicide. We provide ageing formulae and photographic records to facilitate further studies of Grasshopper Buzzard nestling development and reproductive success in the region.     

Reproductive biology and ecology of white‐winged trumpeters (Psophia leucoptera) and recommendations for the breeding of captive trumpeters

The reproductive biology and ecology of a wild population of white‐winged trumpeters (Psophia leucoptera) were studied in southeastern Peru from 1983 to 1987. Because little information is available about any of the trumpeter species and because trumpeters have proven difficult to breed in captivity, information relevant to breeding and management of captive trumpeters is reported in this paper. White‐winged trumpeters lived in territorial social groups that ranged in size from four to 13 individuals. A typical territorial group contained three adult males, two adult females, and several sexually immature offspring, but smaller temporary groups sometimes formed for the duration of the breeding season. Only the dominant female contributed eggs to the clutch, and all adult males in the group competed to obtain copulations with her. Eggs were laid in elevated nesting cavities and no nest was constructed. The average clutch size was three eggs and incubation was not begun until the final egg was laid. The dominant male and female shared most of the incubation duties, but subordinate males covered approximately 15% of the incubation shifts. Eggs hatched approximately 27 days after incubation was begun and chicks left the nesting cavity the day after they hatched. Chicks were completely dependent on older birds to feed them for their first 3 weeks and then gradually began to feed themselves more and more food. The subordinate adult males fed chicks the most food, the dominant male and female and older offspring fed chicks an intermediate amount, and the subordinate adult female fed chicks the least. Young chicks behaved aggressively toward each other but were separated by adults before they injured each other. If at least one chick from the clutch survived, trumpeters did not breed again until the beginning of the next breeding season the following year. Zoo Biol 19:65–84, 2000. © 2000 Wiley‐Liss, Inc.