摘要:

SummaryBreeding phenology, success and nest attendance of Antarctic PetrelsThalassoica antarcticaand Southern FulmarsFulmarus glacialoidesat the Rauer Group (68°51'S, 77°50'E), East Antarctica, are discussed. Most data were collected on Hop Island (68°50'S, 77°42'E) in January and February 1988, and from December 1988 to March 1989. Observations extended from the late stages of incubation to post-guard or fledging periods. Some annual breeding indices collected from 1983 onwards at census sites are compared with meteorological data and the extent of fast ice for the nearby Davis Station (68°35'S, 77°58'E). Both species had a restricted hatching period, reflecting a brief and synchronised egg-laying period, typical of other southern fulmarine petrels. Antarctic Petrel chicks hatched from 4 January (1989), andc.90% appeared by 16 January (both years). Southern Fulmar hatching began on 21 January (1988) and almost all chicks appeared by 6 February (both years). Adult attendance at nests declined with increasing chick age. For Antarctic Petrels, this was most marked at about 11 days; no chicks had continuously attendant adults after 24 days, although adults returned to feed them. Incubation shifts in Southern Fulmars were longer than shifts following hatching and the post-guard period started, on average, 13 days after hatching. Egg and chick losses varied between years and sites. The South Polar SkuaCatharacta maccormickiwas apparently involved in the majority of losses. Nest sites of both species resemble those elsewhere: Southern Fulmars may require steeper sites, allowing a fall away from colonies. Antarctic Petrels are less affected by accumulation of snow or ice and shelter from katabatic winds may be important. Although weather may modify breeding success locally, annual success must depend on the ability of parents to produce eggs and feed chicks: this may be moderated by the extent and persistence of pack ice.

ISSN:0158-4197    

DOI:10.1071/MU9920193

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

SummaryFoods of adult Antarctic PetrelsThalassoica antarcticaand Southern FulmarsFulmarus glacialoidesbreeding on Hop Island, Rauer Group, East Antarctica, were obtained using water-offloading techniques, from late incubation to late post-guard periods. Both species took mainly krill, particularlyEuphausia superba, and fish, almost entirelyPleuragramma antarcticum;other crustaceans and cephalopods were infrequent. The increase ofE. crystal-lorophias, particularly in Southern Fulmars, was associated with increasedP. antarcticumin the diet of both species. No significant differences in prey sizes were detected but the smaller Antarctic Petrel tended to contain more fish and less krill. Results are compared with previous studies; all show a restricted number of prey species, and a wide range of prey sizes. Variations in proportions of specific groups may reflect sampling methods, but more likely reflect prey abundance or availability. The importance of ice cover is discussed. Inshore feeding by Southern Fulmars, and differing feeding methods, may allow segregation of foraging: assuming similar rates of digestion, the more digested food in Antarctic Petrels suggests a greater foraging range. This is supported by differences in attendance shifts at nests. Growth rates of chicks deprived a meal were compared with those of chicks given supplementary meals, and controls. Deprivation apparently caused no immediate effects; additional meals tended to increase growth of Antarctic Petrel chicks. Small sample sizes confounded interpretation but suggested that Antarctic Petrels, which typically breed further south than Southern Fulmars, are better adapted to local conditions where sympatric with Southern Fulmars. The slightly larger volumes of oil retrieved with Antarctic Petrel food supports this since oil offers a more efficient method of transporting food to growing chicks. For these two fulmarine petrels, segregation of food requirements may be by foraging differences; where sympatric, segregation of peak demands may also result from separation of laying periods.

ISSN:0158-4197    

DOI:10.1071/MU9920207

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

SummarySeabirds in Madang Province waters were surveyed during 40 small-boat trips from 20 September to 27 November 1989. At least 11 579 individuals of 21 species were identified. None nested near Madang. The seasonal status, abundance, habitat distribution and day-roosting habits are reported for each species. Heinroth's ShearwaterPuffinus heinrothiand Grey-backed TernSterna lunataare documented for the first time in mainland New Guinea waters, but at least the former is believed to be regular near Madang. Ten species of terns represented 93.7% of all seabirds. Seven boreal migrant species including Common TernS. hirundo(69.1% of all identified seabirds) and Little Tern S.albifrons(6.0%) contributed 76.9% of the total. Twelve tropical species made up nearly all of the remainder. Total abundance was greatest in the inshore and harbour zones, but species diversity increased with distance offshore. Only six species (all terns) were seen roosting at only two sites on land or on a channel marker. Terns and boobies rested on any suitable flotsam, from coconuts to huge offshore rafts that included trees. Foraging distributions of these birds appeared to be influenced by the ephemeral distributions of both flotsam and feeding tuna schools. In the absence of flotsam, terns waiting for feeding tuna to resurface often settled on the water in dense flocks.

ISSN:0158-4197    

DOI:10.1071/MU9920223

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

SummaryObservations of Bell MinerManorina melanophrysfemale breeders being fed by one or more nest attendants while the former were incubating or brooding are reported. This behaviour might be the result of some male helpers trying to establish a mating relationship with the breeding female.

ISSN:0158-4197    

DOI:10.1071/MU9920233

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

SummaryThe potential influence of rainfall, habitat quality and group size on breeding success in Superb Fairy-wrens was investigated in a study of 161 nesting attempts by 62 breeding units over five breeding seasons near Armidale, New South Wales. Breeding seasons started earlier, and lasted longer, in years with higher than average rainfall, and resulted in higher seasonal breeding success. Proportionately more four-egg clutches than three-egg clutches were laid in years of higher rainfall. Breeding success was correlated with habitat quality (bramble area per territory) and Superb Fairy-wrens on territories with larger areas of brambles made more nest attempts and fledged more offspring per season than did birds with smaller areas of brambles. Brambles appeared to have a cumulative effect on breeding success due to better protection from nest predators. No effect of helpers on breeding success per nest attempt was evident and groups with helpers hatched no more nestlings per egg laid and fledged no more offspring per nestling hatched than did pairs. Groups and pairs did not differ significantly in the number of nesting attempts made or the number of fledglings produced per season although groups tended to re-nest sooner after successful nesting attempts than did pairs. It is suggested that the maintenance of cooperative breeding in Superb Fairy-wrens is not reliant on reproductive advantages arising from the presence of helpers at the nest but may be favoured by variation in territory quality.

ISSN:0158-4197    

DOI:10.1071/MU9920238

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9920244

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9920246

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9920248

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9920250

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9920255

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor