摘要:

Moult scores were collected from colour‐ringed individuals of known reproductive status of the two species of giant petrel,Macronectes halliandM. giganteus, at Bird Island, South Georgia between 1978–81.Both species showed a substantial overlap between breeding and wing‐moult, unlike most other Southern Ocean seabirds. Males started moult before females and both sexes ofM. giganteusmoulted at an earlier stage of the breeding cycle thanM. halli, which breeds six weeks earlier than its congener.Changes in moult rate during the breeding season are documented for both species, withId. hallishowing a rapid increase as the chick nears fledging. MaleM. giganteusshow a notably different pattern to the other three species‐sex groups, starting moult much earlier (at egg‐laying), with greater individual synchrony and usually suspending primary moult throughout the main chick growth period, whereas only two male M.halliand no females of either species suspended moult. Differences in pattern, timing and rate of moult are interpreted in terms of availability of food resources and the competing energy demands of other activities, especially chick‐rearing.Completion of primary moult could not be observed in the field but was estimated using data frcsm non‐breeding birds and failed breeders; the latter started a rapid moult almost immediately they failed. In both sexes of both species moult is probably concluded at least by early winter.The general pattern of moult in giant petrels at Bird Island is contrasted with that of other populations and species of Southern Ocean seabirds. It is suggested that the unusually extensive overlap between breeding and moult in giant petrels is a consequence of the very abundant and easily available summer food supplies (especially carrion) and the much diminished winter resources, favouring a completion of moult by the beginning

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb07993.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The behaviour, growth and survival of Ringed Plover chicks were studied in 1974 at Mestersvig, northeast Greenland, and from 1973 to 1976 at Lindisfarne, northeast England. Post‐fledging survival, dispersal and recruitment were also investigated for the Lindisfarne population.Growth rates were similar in both study areas, and to those reported from other sites. A diurnal rhythm in feeding activity was more evident in the Arctic than at temperate latitudes, despite continuous daylight in the former area. This was correlated with low nocturnal temperatures and prey availability. It is concluded that food supply did not limit growth or chick survival in either study area. Brooding decreased progressively during the pre‐fledging period; the relationship of brooding period to age, environmental conditions and area was investigated. The adaptations of feeding and brooding behaviour for arctic and temperate breeding Ringed Plovers are discussed.Survival from hatching to fledging varied between 40% and 60% in different areas and years, and at least 59% of birds survived from fledging to about one year old. Minimum survival from one to two years old was only 57%. but year‐to‐year survival of older birds was higher, that of breeding adults being at least so?;. Most birds returned to the breeding area and attempted to breed when one year old. The extent of dispersal from Lindisfarne and the wintering areas of the Lindisfarne‐breeding birds are inv

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb07994.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Red‐cheeked Cordon BleusU. bengalusforage on bare patches of ground for fallen grass seeds and termites in particular home ranges. Foraging is confined to shaded areas in the middle parts of the day but birds exploit places exposed to the full sun in the early mornings and late afternoons. They mostly occur in pairs but often aggregate to form temporary foraging groups. Although birds in groups spend less time vigilant than those foraging alone, they react sooner than them to approaching danger. Birds foraging in pairs peck more rapidly than those in other situations and it is suggested that one advantage of forming permanent pair bonds is that paired birds forage more efficiently than unpaired ones in preparation for the coming breeding season. Flight calls, contact calls and alarm calls are given in specific behavioural contexts. Birds make contact calls when they become separated from their mates and evidently use them to re‐locate one another. It is shown experimentally that members of pairs can recognize one another's contact ca

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb07995.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

There was considerable variation in winter territoriality among Mute Swan pairs around Oxford, though most pairs maintained their territories for at least half the winter. Variation was associated with temperature and with territory quality pairs left their territories most commonly during the coldest months of the winter, and pairs on good territories, with abundant vegetation and accessible pasture. stayed longer on territory than those on poor territories with sparse vegetation and little pasture. As in other species, exclusive territorial defence was maintained at intermediate levels of resource availability, and flocks were able to settle on a few particularly good territories. Circumstantial evidence suggested that winter territories may be maintained not only to provide an adequate food supply for the owners but also to ensure access to a brerding site by preventing other individuals from taking over the area.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb07996.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

This paper discusses the importance of female choice and intrasexual competition in lek species. The importance of phenotypic differences between individuals is stressed. Reproductive constraints limit the possible behavioural strategies that can be used by males and females. I suggest that it is difficult to understand reproductive behaviour without a knowledge of these reproductive constraints.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb07997.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Moult in Malayan Barn OwlsTyto albawas studied in two pairs of wild collected captive birds and from feathers taken from nest sites throughout peninsular Malaysia.Post‐juvenile captive birds moulted nearly to completion prior to first breeding, beginning with P6 at a mean age of 301.5 days. This contrasted with the only other study of moult in captive Barn Ow‐Is in Germany when moult began at an age of 400 days, and then continued for a protracted period of two years separated by a suspension of moult during the normal breeding season.The complex sequence of moult in primaries and secondaries both in the Malayan and German birds was similar.Moult among adult Malayan birds in the wild showed a broad and somebyhat irregular seasonal trend With lower incidence during peak breeding peri

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb07998.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The breeding biology of the Pacific Swallow was studied in Malaysia. Time‐budgets and preliminary energy‐budgets were calculated for different stages of the breeding cycle. Breeding was seasonal, the first eggs were laid in the first week of March from 1978 to 1982. The nest was a mud cup built under an overhang, often on man‐made structures over water. The mean clutch size was 2.98 eggs. So more than two successful clutches were ever raised, although up to four sets of eggs can be laid if clutches are lost. The incubation period was 16.2 days and the nestling period 19–21 days. Nestling weights showed the typical hirundine recession before fledging. The mean brood size was 2.32 and there was no evidence of undernourishment in larger broods. Nesting success was lower than for temperate hirundines but high for a tropical passerine. Incubation duties were carried out by the female alone but both parents fed the brood. The male never delivered more than 44% of the total feeds. Daily energy expenditure varied from 3.44–4.9×BMR depending upon the stage of the bree

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb07999.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Samples of Ptarmigan eggs were hatched in captivity. They had been taken from ground adjacent to study areas where the wild birds' breeding success by early August, and their food plants, were measured.Almost all deaths of chicks in captivity occurred within a few days of hatching and examination postmortem showed no specific cause. The proportion of chicks which died in captivity before 15 days of age varied markedly between years and study areas. These variations occurred in parallel with variations in breeding success in the wild populations from which the eggs had been taken. It was concluded that the survival of chicks both in captivity and in the wild was determined in part before the eggs hatched.Variations in breeding success from year to year were correlated with the number of days that the food plants had been growing before the hens finished laying. Breeding success in the wild and chick survival in captivity were better for a ‘rich’ area overlying some base‐rich rocks than for a ‘poor’ one overlying granite and with less blaeberry. It was inferred that, as in Red Grouse, maternal nutrition affected breeding success through the quality of

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb08000.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The polygynous mating system of the Fan‐tailed WarblerCisticola juqcidiswas investigated between 1978 and 1981. The male warbler builds many nests unaided; however, he has no more than one active vacant nest for courting at any time. Nest building lasted from April until August. After completing the outer fabric of a nest, the male advertised it and led a female to the nest site by a unique invitation flight. On average a male built 6.5 nests during one breeding season and three of them were accepted by females. The most successful male completed 18 nests, and mated with 11 females. Out of a total of 111 males which established a territory, 30 had no mate, 14 were monogamous, and the rest were polygynous. About 50 to 70% males were polygynous over the four years. The sex ratio varied from 1.41:1 to 2.17:1 (females: male) in the breeding population. It was partly caused by the presence of ‘floating males’. After the completion of the outer fabric of the nest, the male warbler did not take any further role in nesting and caring for young.The polygynous mating system of the Fan‐tailed Warbler is characterized by successive nest building. Its extreme development results from the long breeding period and the male having no role in parent

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb08001.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The behaviour of free‐living Double‐crested and Flightless Cormorants, and the thermoregulation of Flightless Cormorants, were studied in the field to determine the influence of weather and the function of wing‐spreading. The behaviour of both species was sensitive to changes in ambient temperature and insolation intensity. Spread‐winged behaviour in both species w‐as displayed only bywetindividuals and was never accompanied by gular flutter. The frequency of spread‐winged behaviour in Double‐crested Cormorants was not correlated with ambient (shade) temperature or solar intensity. In Flightless Cormorants, however, the frequency of wing‐spreading was positively correlated with ambient temperature, and negatively correlated with insolation intensity. Body temperatures in Flightless Cormorants were statistically higher during the day than during the night, while gular fluttering than while not gular fluttering, and before entering the water than after leaving the water. There were no significant differences in the body temperatures of Flightless Cormorants after wing‐spreading as compared to before ‘sunning’. Spread‐winged behaviour in these cormorants appears to function primarily in wing drying and not in gaining or losing heat, although the ultimate goal of wing drying may be to co

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1984.tb08002.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY