摘要:

SummaryWeathers, W.W., Weathers, D.L.&Seymour, R.S. (1990). Polygyny and reproductive effort in the MalleefowlLeipoa ocellata, Emu90, 1–6.In the mallee scrub of South Australia, a polygynous MalleefowlLeipoa ocellatamated to two females was discovered. Each female laid her eggs in a separate mound of sand and decaying vegetation: one produced a clutch of 30 eggs, the other a clutch of 29 eggs. The male divided his time between the two mounds and females until one of the females disappeared, whereupon he shifted his attention solely to the remaining female and her mound. After seven weeks of inactivity, the abandoned mound's egg chamber remained at 34°C, the normal incubation temperature. The abandoned mound's temperature stability and the male's polygyny may have both been made possible by favorable environmental conditions attributable to higher than normal rainfall.

ISSN:0158-4197    

DOI:10.1071/MU9900001

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

SummaryTidemann, S.C. (1990). Factors affecting territory establishment, size and use by three co-existing species of fairy-wrens (Malurus).Emu90, 7–14.SuperbMalurus cyaneus, VariegatedM. lambertiand White-wingedM. leucopterusFairy-wrens co-existed at Booligal, New South Wales, where their territories overlapped but very few interspecific interactions were observed. Territories were established and maintained by song and less often chases between males. During nesting, the area utilised by the fairy-wrens was smaller than that established earlier. Areas that were grazed heavily were occupied less, especially by Superb Fairy- wrens. Fairy-wrens enlarged their territories during drought. Size of a territory correlated positively generally with the number of bushes contained within it except during drought. Territory size correlated negatively with insect abundance for Superb and White-winged Fairy-wrens only and with the number of groups of each species except where vegetation was patchy. I suggest that territory quality can be described best in terms of food availability, and for gleaning insectivores this may depend on the foraging area available.

ISSN:0158-4197    

DOI:10.1071/MU9900007

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

SummaryClarke, M.F.&Heathcote C.F. (1990). Dispersal, survivorship and demography in the co-operatively-breeding Bell MinerManorina melanophrys. Emu90, 15–23.Females are the dispersing sex in Bell Miners; males tend to be philopatric. The mean age of dispersal (8.0±1.0 months) corresponded closely to the minimum age of first breeding (8.3 months) and may reflect intolerance by females of their sexually mature daughters which may compete for the parental care provided by males. The adult sex ratio was male-biased, probably because of greater dispersal-related mortality suffered by females. Juveniles up to the age of first breeding experienced extremely high mortality (93%). The life expectancy of birds increased dramatically once they reached breeding-age. The number of breeding positions varied little relative to the total number of birds in the social unit. In a social unit of Bell Miners studied over six years there were 6.3 unmated breeding-age birds per breeding vacancy in any month. The level of competitor pressure for breeding positions was more severe for males than females due to the skewed sex-ratio.

ISSN:0158-4197    

DOI:10.1071/MU9900015

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

SummaryMiskelly, C.M. (1990). Effects of the 1982–83 El Niño event on two endemic landbirds on the Snares Islands, New Zealand.Emu90, 24–27.The major El Niño/Southern Oscillation event of 1982–83 disrupted weather patterns at the Snares Islands in the New Zealand subantarctic. There was an abnormal preponderance of westerly and south—westerly winds, rainfall was 3.6 times greater than the mean for the succeeding four summers and temperatures were significantly cooler than three of the four subsequent summers. Compared with four succeeding years, the few Snares Island SnipeCoenocorypha aucklandica huegelithat bred in 1982–83 did so 24 days later on average, breeding was successful in significantly fewer territories (20%c.f.46–84%) and 3.1 times fewer young per territory left nests (0.4c.f.0.91–1.90). Adult mortality measured by density in the winter following the El Niño was 2.5 times greater than the mean for the 1984 to 1987 winters. High adult mortality and low recruitment of juveniles following the 1982–83 season resulted in a low density of snipe in the study area in 1983–84. Only one Black TitPetroica macrocephala dannefaerdinest was found in 1982–83. The first Black Tit fledglings seen in 1982–83 were a full month later than the mean date for three subsequent years. Widespread reproductive failure and delayed breeding by Snares Island Snipe and Black Tit in 1982–83 and high mortality of adult Snares Island Snipe during the 1983 winter were probably caused by a reduction in their invertebrate food supply.

ISSN:0158-4197    

DOI:10.1071/MU9900024

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

SummaryMiskelly, C.M. (1990). Aerial displaying and flying ability of Chatham Island SnipeCoenocorypha pusillaand New Zealand Snipe C.aucklandica Emu90, 28–32.Chatham Island SnipeCoenocorypha pusillaand New Zealand SnipeC. aucklandicawere studied intensively during one and six breeding seasons respectively, and observations of aerial displays and related behaviours recorded. Chatham Island Snipe gave three types of acoustic aerial displays. The displays were performed only at night. Type 1 was a strident monosyllabic call, also given in several contexts on the ground. Type 2 was a series of disyllabic calls identical to a common territorial display given on the ground. Type 3 began with a series of disyllabic calls and ended with a non-vocal‘roar’considered homologous to the‘drumming’displays ofGallinagosnipes. Evidence for non-vocal acoustic displaying by three subspecies of New Zealand Snipe is discussed. The intensively studied Snares Island Snipe C.aucklandica huegeliwas not seen to give aerial displays. Chatham Island Snipe were flushed significantly more frequently and flew further than Snares Island Snipe, and had significantly lower wing-loadings. The aerial displays of Chatham Island Snipe were similar to descriptions of aerial displays of the‘Chubbia’snipes of South America: Cordilleran SnipeGallinago stricklandii, Andean SnipeG. jamesoniand Imperial SnipeG. imperialis.

ISSN:0158-4197    

DOI:10.1071/MU9900028

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

SummaryLill, A.&Fell, P.J. (1990). Egg composition in some Australian birds.Emu90, 33–39.Egg composition was examined in 17 altricial Australian bird species. The shell fraction comprised 7.4–13.6% (mean 8.7%) of fresh egg mass. Yolk comprised 17.5–29.9% (mean 23.5%), lipid 5.1–8.4% (mean 6.7%) and water 76.4–83.9% (mean 80.3%) of the fresh egg contents. On average, yolk contained 46.2% solids, of which lipids comprised 60.8%, and had an energy density of 13.87 kJg−1wet mass. Egg composition was not influenced by diet or clutch size and was similar to that of altricial species breeding elsewhere, emphasising the fundamental nature of its functional relationship with hatchling maturity. However, we identified some possible exceptions to the hatchling maturity-yolk content rule, in which pre-fledging growth rate appeared to influence fractional yolk content. The water fraction of the egg contents and, to a lesser extent, of the albumen component decreased as a function of fractional yolk content. The lipid fraction of the contents, but not of the yolk solids, increased in parallel with fractional yolk content. Consequently, the species whose eggs have larger fractional yolk contents have a relatively greater scope for the biosynthesis and maintenance of embryonic tissue and/or the production of hatchling yolk reserves.

ISSN:0158-4197    

DOI:10.1071/MU9900033

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

SummaryRobinson, D. (1990). The nesting ecology of sympatric Scarlet RobinPetroica multicolorand Flame RobinP. phoeniceapopulations in open eucalypt forest.Emu90, 40–52.This paper compares the nesting ecology of interspecifically territorial Scarlet Robins and Flame Robins at a site in southeastern New South Wales. Nest site competition was not apparent between the two species of robin, and competition for food was instead considered to be a more likely cause of their interspecific territorial behaviour. The sedentary Scarlet Robin began breeding a few weeks earlier than the migratory Flame Robin but, because of high rates of nest failure and repeat laying of clutches, the two species' breeding seasons overlapped extensively. Ten per cent of Scarlet Robins' nests produced one or more young. Twenty-five per cent of Flame Robins' nests were successful. Nest failures were mostly due to predation of eggs and young, notably by snakes and birds. I suggest that high rates of predation may have affected clutch sizes and nesting habits of Australian birds, although climatic stability and year-round availability of food probably comprise the most important selective forces on Australian birds' life history traits

ISSN:0158-4197    

DOI:10.1071/MU9900040

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

SummarySeddon, P.J.&van Heezik, Y. (1990). Diving depths of the Yellow-eyed PenguinMegadyptes antipodes. Emu90, 53–57.The mean maximum dive depth of 43 dives by Yellow-eyed PenguinsMegadyptes antipodesmeasured using capillary depth recorders during incubation was 34±8 m, (19–56 m). There were no differences in the maximum dive depths of males and females overall, or within mated pairs. In conjunction with dietary and foraging trip duration evidence, maximum dive depths suggest foraging Yellow-eyed Penguins remain within 7–13 km of the shore.

ISSN:0158-4197    

DOI:10.1071/MU9900053

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9900058

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

ISSN:0158-4197    

DOI:10.1071/MU9900060

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor