摘要:

SUMMARYNectar‐feeding of birds was recorded during a phenological study of the woody vegetation at Zaria in the Northern Guinea Savanna of Nigeria.Throughout the dry season when it is in a non‐breeding state, the Scarlet‐breasted SunbirdNectarinia senegalensisconcentrates on the ornithophilous plants which flower in an overlapping sequence, and exploits the smaller‐flowered species less frequently. As the flowering of the ornithophilous species decreases at the end of the dry season, the range of other plants exploited increases but, in the early rains as the flowering of the indigenous plants tails off, the sunbird switches to ornamental exotics and the indigenous, shrubby parasite,Tapinanthus globiferus.The bird is more conspicuously insectivorous during the wet season when it breeds. The Pygmy SunbirdAnthreptes platurais a breeding, dry‐season visitor which exploits a somewhat different range of small‐flowered, mainly entomophilous species and some exotics but also takes nectar from those ornithophilous species it can exploit, as well as the chiropterophilousParkia clappertoniana.The bulk of the breeding population leaves the district before the flowering of the indigenous plant tails off. The five other species of sunbird recorded in the district are either very rare residents or more numerous wet‐season visitors and passage migrants for which records of nectar‐feeding are too few to draw conclusions about seasonal changes but the wet‐season visitors appear to rely on the garden exotics in the comparative absence of flowering indigenous plants.Nectar‐feeding onBombax costatumandParkia clappertoniana, where nectar is readily accessible and present in relatively large quantities, was noted for IS species of non‐nectariniid birds, some of which were regular visitors. Some examples of flower consumption probably related to nectar‐fee

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08249.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYThe migration of the CuckooCuculus canorusis described from recoveries of ringed birds. Young birds begin to migrate in August and most go southwards by September—those in continental Europe move southeast, south or southwest, while those from the British Isles move southeast. In spring, migrants arrive in Europe in April/May, second‐(calendar) year birds doing so later than post‐second‐year birds. In autumn old birds depart in advance of first‐year birds; and the individual bird may move stepwise through Europe. Old birds showed a marked tendency to return to the same places inhabited in previous breeding seasons, and birds ringed as nestlings subsequently tended to return to the general vicinity of the n

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08250.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYThe aim of this paper was to assess the status of migrant shorebirds in the Seychelles. Most observations were concentrated on two areas: a 6 ha mudflat at Victoria, Mahé, and open areas of Bird Island.A systematic list of all shorebirds that have been recorded in the Seychelles is given, including data on abundance and their incidence on other islands of the Malagasy region. Most of the Seychelles migrants probably originate from the north and east, i.e., the central and eastern Palaearctic, and arrive after a sea‐crossing of over 1600 km.Highest numbers of species and of individuals occurred in the Seychelles during the northern winter, but about one third of the species recorded were also present, in reduced numbers, in the summer. Few birds in breeding plumage were seen; probably most birds, especially those which summered, were immature. Numbers of both summering and wintering birds varied from year to year, these variations probably being related to breeding success at higher latitud

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08251.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYAt a Kittiwake colony in Northumberland, 80% of those birds which returned to their natal colony to breed were males and these supplied 52% of all male recruits. More females breed away from their natal colony than males. There was no differences in the proportions of young fledged from sites in the centre or at the edge of the colony, or by parents of different experience, which returned to breed. Kittiwakes breed for the first time at ages from 3 to 8 years, but most at 4 or S years old. Males arrive back at the colony at an earlier age than females and breed for the first time one year earlier. Males obtaining sites at the centre of the colony first breed at an earlier age than those at the edges. Neither the age nor the area of first breeding appear to be transmitted from parent to offspring. Males breeding first aged 4 years or younger produced more young than those which first bred aged 5 years or older, despite their partners laying smaller clutches. This difference was most marked among those males recruited to sites in the centre of the colony. The advantage of this earlier breeding is counteracted by a lower survival rate among those males which start to breed at the younger ages. In all breeding Kittiwakes, annual reproductive output increases with experience while annual survival rates decrease. Once they had started to breed, many birds failed to breed in one subsequent season. Nearly 60% of these cases of intermittent breeding occurred in the year following first breeding. Intermittent breeding was most frequent among young birds and among females. It is suggested that each breeding involves a cost to the individual in terms of reduced survival, and that deferred and intermittent breeding are means of guarding survival. A model is proposed whereby the age at which a bird starts to breed, the nesting site which it obtains, and its subsequent breeding strategy result in each individual producing an optimal number of reproducing offspring in its lifetime, relative to its quality.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08252.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08253.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08254.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08255.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08256.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08257.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1977.tb08258.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY