摘要:

The feeding ecology of Lapwing chicks was studied in two agricultural study areas in central Scotland. Chicks probably fed opportunistically rather than selectively and their diet was varied but comprised mainly Coleoptera, leatherjackets (Tipulidae) and earthworms.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02746.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The correction factork(breeding pairs/total count of birds) was measured for two nesting groups of GuillemotsUria aalgeover 6–7 years. The value varied between different subgroups but there were no significant differences between groups or between years. These results, and those from other studies, suggest that a value of 0–67 is applicable to a range of colonies. Values ofkfor RazorbillsAha tardawere more variable. A plea is made for the presentation of original counts rather than ‘corrected’ figures in publish

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02747.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Artificial eggs of six different colours and control eggs of Bush Warblers Cettia diphone were introduced into nests of Bush Warblers, a host of both Little and Himalayan Cuckoos Cuculus poliocephalus and C. saturatw in Japan. All control (chocolate‐brown) and artificial red eggs were accepted; all grey and all white eggs were rejected. The rejection rates of orange, pink and orange spots on grey eggs were 8%, 369; and 55%, respectively. Bush arblers are more likely to reject eggs the more dissimilar they are from their own. The results strengthen the possibility that the chocolate‐brown eggs of Little and Himalayan Cuckoos may have evolved through the discriminative ability of Bush Warblers and their intolerance towards dissimilar e

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02748.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

We describe the vocalizations of the Christmas Island WarblerAcrocephalus aequinoctialis, endemic to Christmas and Washington Islands, central Pacific Ocean, in the absence of other land birds and natural predators. Its vocal signals are simple when compared to mostAcrocephalus.We explain this simplicity as the result of a lack of interspecific interactions, a monogamous life style, large permanent territories, open dry habitat and limited interaction among neighbouring individuals.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02749.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The 16‐year data of a Great Tit population, breeding and overwintering in a nest box area at Oulu, northern Finland, were studied to reveal the factors governing the annual fluctuations in density and local survival. The breeding density at Taskila was high after a cold spring (March‐April) and a warm August the year before was also followed by a large breeding population. A similar relationship resulted for the local survival of fledglings, and there was a tendency for immigrant yearlings to settle to breed in large numbers when the spring was cold. In the north, Great Tits cannot survive the winter in the forests but gather around feeding tables near human settlements. A cold spring evidently suppresses the birds' dispersal before the breeding season. For a population which is time‐limited, it is adaptive to remain in order to breed nearby instead of searching for territories out in the forests when conditions become favourable late in the spring. Thus, the negative correlation between spring temperature and the size of the following breeding population may be the result of a spatial distribution of juveniles achieved by behavioural responses to unfavourable conditions. The causality behind the high survival of resident juveniles after a warm August may be attributable to food availability during the time when the birds undergo their postjuvenile moult, which is an energy‐demanding process. The survival rate of breeding adults was highly dependent on the intensity of nightly predation upon individuals roosting in nest boxes. StoatsMustela erminea, the prime predators, preyed on tits when the populations of their main prey species, small rodents, were low. When the effect of predation was eliminated, the density‐dependent survival of adult birds disappeared. During low predation years the adult survival rate was negatively related to the number of fledglings produced per pair; this suggests that investment in descendants is a substantial survival cost for reproducing in

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02750.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

During the winters of 1979 to 1986, flocks (7–17 per season, 78 total) of Willow TitsParus montanus(generally consisting of an adult pair and four juveniles) were studied in a subalpine mixed forest in Central Norway. The mean survival rate between December and early April for juveniles (0.32) was significantly lower than that found for adults (0.74). As it has previously been found that adult Willow Tits, being dominant, prevent the juveniles in a flock from using preferred foraging sites, a removal experiment was made to see if the survival of juveniles improved when living in flocks with no adults present. After removal of the adult pair from 13 flocks in early January, the juveniles from these flocks survived significantly less well, up to early April, than either the juveniles in 11 flocks in which the adults were present (controlled for flock size) or those in 14 flocks consisting of an adult pair and four juveniles. Despite a skewed access to the resources in favour of dominant adults, the cost of being a subordinate juvenile is probably outweighed by the improved predator evasion and improved food finding efficiency due to the greater experience of the adult pair possessing the territor

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02751.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Starlings, like most other species, show no gonadal development until spring of the year after they hatch, even though they hatch and attain full body size during long days. This could be because they develop in a physiological state analogous to that of photorefractory adults and so need to experience short days in order to activate the reproductive system. To test this possibility, young were hand‐reared under different photoperiodic regimes. Young raised under constant long days showed no gonadal development, nor did birds initially raised under short days and then transferred to long days at 3 weeks of age. However, birds transferred from short to long days at 10 weeks of age did show gonadal development, followed by gonadal regression, while birds raised under constant short days showed slow continual gonadal development. This last group, unlike the other three groups, did not moult into adult plumage. Since 4 weeks of long days are required to terminate photorefractoriness in adult Starlings, these results demonstrate that the reproductive system of young birds is in a similar state to that of photorefractory adults, and hence that puberty is analogous to the termination of photofractorines

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02752.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The social behaviour of non‐breeding individuals in a colour‐marked population of Magpies was studied. In early autumn most non‐breeders began to forage in a common area, the ‘Non‐breeding Flock Area’. A few individuals remained on their natal territories away from the flock area as solitary non‐breeders. Most non‐breeders were first‐year birds, but some were second years or adults which no longer held a territory. Birds foraged in groups, their food intake rate differing with both group size and location. It appeared that the area in which birds foraged had a significant effect on food intake rate; foraging groups tended to form at sites rich in food. There was a dominance hierarchy amongst non‐breeders; an individual's foraging behaviour, survivorship and chances of breeding were status dependent, with subordinates feeding less in groups and being less likely to survive and breed. Solitary individuals' chances of breeding were similar to those of high status birds, although their survivorship to breeding age may have been lower. Non‐breeding Magpies are compared with non‐breeders of other species and the factors which may influence their social behaviour are discussed. It is suggested that remaining as a solitary non‐breeder is a viable alternative to becoming a low‐status

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02753.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02754.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Brickell, N. 1988. Ducks, Geese and Swans of Africa and its Outlying Islands.Burr, E.W. (ed.) 1987. Companion Bird Medicine.Clark, W.S.&Wheeler, B.K. 1987.Colston, P.&Burton, P. 1988.Cramp, S. (ed.) 1988. Handbook of the Birds of Europe, the Middle East and North Africa: the Birds of the Western Palearctic, Vol. V.Hill, D.&Robertson, P. 1988.Hollom, P.A.D., Porter, R.F., Christensen, S.&Willis, 1.1988. Birds of the Middle East and North Africa: A Companion Guide.Ilyichev, V.D.&Zubakin, V.A. (eds) 1988. The Birds of the USSR: Lari. (Russian).Johnsgard, P. 1988. The Quails, Partridges and Francolins of the World.Pätzold, R. 1987. Die Ohrenlerche.Peck, G.K.&James, R.D. 1987. Breeding Birds of Ontario. Nidology and Distribution. Vol. 2: Passerines.Seller, T.J. 1987. Bird Respiration. Vols 1&2.Wells, R.G.&Belyavin, C.G. 1987. Egg Quality–Current Problems and Recent Advances. Poultry Science Symposium No.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1989.tb02756.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY