摘要:

SummaryThe Greenish Warbler is an abundant entirely insectivorous Pafaearctic migrant wintering in the tropical deciduous forests of India and east Asia. A population was studied at one locality in the eastern Ghats of south India over one winter, with a short return the following winter. Individuals maintain, and annually re‐occupy, territories throughout their seven or eight months stay. A general account of territorial behaviour is given.There is much evidence that food is critically short, particularly during the months of December to February and March, which coincides with the end of the dry season. Because of the short duration of the study, there are shortcomings in data presented. Nevertheless there is evidence that territories vary severalfold in quality and individual birds' behaviour and survival probability are correlated with this. It is suggested that territorial behaviour is the best individual strategy for long‐term resource management. The presence of food competitors can alter this behaviour, much as changes in food dispersion are known to. The ability to control return time to a patch as a subsidiary function for territoriality is briefly discus

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00920.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryIn captive BudgerigarsMelopsitticus undulatusmoult of primaries started in the middle of the tract and moved progressively inwards and outwards, the inner feathers being replaced faster than the outer ones. Full replacement of primaries took six to eight months and a new cycle of moult usually started before completion of the old cycle. Moult of secondaries followed no clear pattern and occurred less frequently than moult of primaries. Moult of rectrices started with the middle pair and moved progressively outwards on both sides. Complete moult of rectrices took about six months and a new cycle often started before completion of the old. Moult of the head and body occurred intermittently throughout the year. Birds fledged in juvenal plumage, they passed into first basic plumage with a partial moult (head and body feathers) and into definitive basic plumage with a moult of all contour feathers.In the field in inland mid‐eastern Australia, there were some birds replacing feathers and some with complete plumage in most months of the year. Birds with complete plumage may have been between moults or within a moult and between replacement of feathers. The proportion of birds in moult did not increase in intensity after breeding, or cease during breeding or before movements. Some birds of both sexes with gonads in a reproductive condition were replacing feathers. Rirds that were replacing feathers had similar lipid deposits to birds that had a complete plumag

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00921.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummarySome 5700 Ruffs were ringed in the southern Kenyan rift valley during 1967–79, mainly at Lakes Nakuru and Magadi. These have produced 15 recoveries outside East Africa, 14 in Siberia between 73° and 154°E and one in India.Adult males returned to Kenya mainly during August, and females during late August and early September. Females greatly outnumbered males at all times. Most wintering males departed late in March and early in April, but females not until about a month later. First‐year birds appeared from the end of August, but remained in low numbers until late October or November. Most departed during April and May, but a few females oversummered. First‐year birds typically accounted for about 25% of the wintering Nakuru females, but about 50% of those at Magadi. At both sites they accounted for a higher proportion of male birds than females.Most of the birds at Nakuru throughout late August to May appeared to be local winterers, and many individuals remained in the area for many months each year. Retrapping indicated that approximately 60% of each season's birds returned the following season.Adult males and most adult females commenced pre‐winter wing moult before arrival, but completed most of it in Kenya. Males moulted 3–4 weeks ahead of females, and most had finished before December. Females typically finished during December and early January. Most second year birds timed their pre‐winter moult similarly to older adults. Suspension was recorded in over 15% of all moulting birds examined. Adult pre‐summer moult involved most or all of the tertials, some or all of the tail feathers, most of the inner wing coverts and the body and head plumage. It occurred mainly during January to March (males) or February to April (females), although tertial renewal commonly began a month earlier. Males showed no sign in Kenya of the supplementary prenuptial moult.First‐year birds moulted from juvenile into first winter body plumage during late September to November. They underwent a pre‐summer moult similar in extent and timing to that of adults, and again about a month earlier in males than females. Spring feathers acquired were often as brightly coloured as those of adults. About 15% of first‐year birds renewed their outer 2–4 pairs of large primaries during January to April.Adult and first‐year birds fattened before spring departure, commonly reaching weights 30–60% above winter mean. Weights of adult males peaked early in April, those of adult females early in May, and those of first‐winter females later in May. Weights were relatively high also during August and September. This was due to the arrival of wintering birds carrying ‘spare’ reserves, and also apparently to the presence of a late moulting fattening passage contingent.The wing length of newly moulted adults was about 3 mm longer than that of newly arrived first‐year birds, but there was no evidence of an increase in the wing kngth of adults with successive moults. Adult wing length decreased by 4–5 mm between the completion of one moult and the middle stages of the next.The migrations and annual timetable of Kenyan wintering Ruffs are discussed, and their moult strategy is compare

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00922.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe behaviour of helpers at nests of Northwestern Crows was studied on Mandarte Island and Mitlenatch Island, British Columbia. Not all nests had a helper and there was only one helper per nest. Helpers participated in varying degrees in the defence of the territory and nest, feeding of the nestlings and fledglings and they cached food on the territory. Adult males fed helpers, and helpers obtained most of their food on the adults' territory. Adults with helpers laid larger clutches and produced more fledglings per nest than adults without helpers. It is suggested that cooperative breeding in the Northwestern Crow is of recent origin.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00923.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe behaviour and ecology of unmarked MagpiesPica picaliving in the Cotswolds were investigated over 18 months. The spacing of nests was significantly more regular than random and breeding pairs defended territories throughout the year. In winter pairs occasionally left territories to feed with non‐breeding birds which flocked throughout the year.Magpies in flocks had a higher averiage feeding rate than birds alone or in pairs. Aggression rates in flocks increased as birds fed closer together and as food patches became richer.Agonistic interactions between CrowsCorvus coroneand Magpies were common; Crows frequently dominated Magpies in disputes over food, and Crows also ate Magpie eggs and young. Single Magpies were most often chased by Crows while Magpies in flocks were able to feed longer in the presence of Crows.Differences in fledgling success among breeding pairs were related to the location of nests; Magpie pairs breeding near Crow nests suffered higher rates of agonistic encounters with Crows and also produced fewer fledglings than did Magpies breeding at greater distances from Crow nests. Magpie nests were located nearer human habitations than were Crow nest

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00924.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00925.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00926.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00927.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00928.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1981.tb00929.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY