ISSN:0158-4197    

DOI:10.1071/MU9860001

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SUMMARYBELL, H.L. 1986. Sexual differences in the behaviour of wintering Golden WhistlersPachycephala pectoralisat Wollomombi, N.S.W. Emu 86: 2–11.Golden Whistlers are wintering migrants to Wollomombi, 42 km east of Armidale, N.S.W., where they re-occupy territories annually. Males forage in the tree canopy, snatching and gleaning, mainly off leaves. Females forage in the understorey, feeding more off bark and gleaning more than do the males. Females regularly join mixed-species feeding flocks of a variety of species, whereas males rarely do. The brightly-coloured males are attracted to other species with yellow plumage, both in and out of mixed flocks.Sexual differences in foraging probably reduce intraspecific competition at a time when food is relatively scarce.

ISSN:0158-4197    

DOI:10.1071/MU9860002

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SUMMARYFord, J. 1985. Phylogeny of the acanthizid warbler genusGerygonebased on numerical analyses of morphological characters. Emu 86: 12–22.Cladograms, both rooted and unrooted, and phenograms of species in the genusGerygonewere obtained by numerical analyses of a matrix of thirty morphological characters divided into various states. Phylogenetic relationships so deduced were generally in agreement and indicated that the ancestral gerygone was possibly a pale-bellied bird, somewhat resembling bothG. moukiand G. fusca, which originated in Australo-Papua. No evidence was obtained in support of a Tumbunan zoogeographical origin. The gerygones of the islands in the South-west Pacific have been derived from two Australian lineages: thefuscaandmoukigroups. Those of the Malayo-Indonesian chain of islands appear to be offshoots ofG. olivaceoand perhapsG. fuscastocks. The relationships ofG. dorsalis, as assessed by the dendrograms of this study, are not entirely in accord with previous views, forG. dorsalisappears to be the sister group of theG. magnirostris—G. chrysogastercomplex.

ISSN:0158-4197    

DOI:10.1071/MU9860012

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SUMMARYLANGHAM, N.P.&K. HULSMAN. 1986. The breeding biology of the Crested TernSterna bergii.Emu 86: 23–32. The breeding biology of the Crested TernSterna bergiiwas studied on One Tree Island, Capricornia section of the Great Barrier Reef Marine Park, Australia. The dense nesting habit with its associated adaptations resemble those found in related species of terns. Clutch size was 1.01 with a mean incubation period of 28 days. Laying was spread over 53 days, but individual subcolonies were more synchronised (18±11.5 days). Hatching success in 1979/80 was 69%, most failures being attributed to predation by the Silver GullLarus novaehollandiae.Smaller subcolonies with proportionally more nests on the perimeter were subjected to greater predation of eggs than were large subcolonies. Overall, there was a decline in hatching success with season. Fledging success was high (85%) with most mortality in 1979/80 being the result of a tropical cyclone. Gulls stole from a third to half of the fish brought to the colony in January 1982. Fledging period varied between 35–43 days. The growth constant (K) was about 0.120, compared with 0.165 for the north temperate Sandwich TernSterna sandvicensis.These results are discussed with particular reference to Silver Gull predation.

ISSN:0158-4197    

DOI:10.1071/MU9860023

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SUMMARYNELSON, J.B. and D. POWELL. 1986. The breeding ecology of Abbott's BoobySula abbotti.Emu 86: 33–46. A survey of 2 636 sites showed that Abbott's Booby nests mainly inPlanchonellaandEugenia, the two main emergent forest trees, andCeltisandTristeropsis.Most nests face north-west, which allows birds to land into the wind during the period when visits to the nest are most frequent. Comparison of present distribution with that in 1967 shows that preference for certain areas has been strongly maintained. Boobies do not colonize hitherto unoccupied areas when displaced. Substantial amounts of preferred habitat have been destroyed and there may be further fragmentation of the remainder.Fidelity to site and mate is, from circumstancial evidence, high. Pairs that complete a successful breeding in August or September usually return the following April. The breeding cycle (c.504 days) comprises some 66 days pre-laying activities, 57 days incubation, 151 days fledging period and 230 days post-fledging feeding. Seventy per cent of eggs are laid between mid-May and mid-July. Some pairs laid in the same year that their juvenile successfully departed and some laid later in the year in which their free-flying juvenile died, or in the year after their previous laying. These cases constitute important departures from normal biennal breeding.In any year about 20% of site-owning pairs are not engaged in breeding. 1.27 eggs per pair per two years were laid and 0.196 young per pair per year, or one successful offspring in 5.1 years, were reared. Breeding success (independent young reared from eggs laid) is highly variable from cycle to cycle, on average between 26.5 and 33.3% but in some cycles less than 10%. Success appears to increase with experience. About 23.8 years are required for a breeding pair to replace themselves. Most of 169 deaths among young Abbott's were due to starvation, mostly in March. Cyclones may kill 20% of free-flying juveniles. Starving, free-flying young may drop below 50% of adult weight. Weight at fledging is 85% mean adult weight.Young Abbott's were observed at the nest-site on 98.1% of observer visits in January/February and 83.5% of visits during the six weeks prior to final departure. The young are fed on averages about twice a week in the monsoon period, though often much less. Most young take their first flight in December or January and are at risk from clumsy landings, and from attack by frigatebirds (Fregataspp) especially in partly-cleared areas. They depart abruptly, mainly in July to September.On the whole of Christmas Island, around 900 pairs laid eggs in 1981 and 800 in 1982. The total number of pairs engaged in breeding in 1982 (tending eggs or young of any age) was estimated to be 1 136 pairs. There is a substantial number of non-breeders on the island.

ISSN:0158-4197    

DOI:10.1071/MU9860033

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9860047

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9860051

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9860053

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9860058

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor