ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00831.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryThe breeding ecology of the New World race of the Royal TernSterna maxima maximawas studied at colonies in Virginia and North Carolina, U.S.A., from 1967 to 1970.Colony sites are quite varied, but isolation, good distance visibility and (especially) freedom from quadruped predators seem important if not essential prerequisites.In Virginia, most adults arrive at the colony site in the last few days of March. Courtship, displaying and copulation take place at, near, and some distance from the colony site. In this the Royal Tern differs from its near relativeS. sandvicensis sandvicensiswhich carries out these activities away from the colony site, presumably as an anti‐predator device.Courtship displays are not described, but in their essentials are similar to those of other terns. Copulations continue throughout incubation and gradually disappear when the eggs hatch. No post‐copulatory displays are known. Some synchrony of egg‐laying is evident, but no “mass laying” occurs, the colony increasing in size steadily over a period of weeks and months. Defaecation on the nest is normal and probably serves to strengthen the nest rim against flooding by high tides.Contrary to published reports, the normal clutch is one; the largest is two, probably often from two different females. All incubating adults examined had two brood patches.Average egg measurements are 63 × 44‐5 mm, and average egg weight is 64.3 g. Egg colour varies greatly, and evaluation is difficult. Eggs are probably not cryptically coloured and individual variation, as well as nest‐site, are used by returning adults to identify their own eggs.Average maximum nest density isc.7/m2.Sterna sandvicensis acuflavidanests regularly, if not obligatorily, withm. maxima;interactions between the two, and possible benefits accruing to each, are discussed. Unhatched eggs were significantly nearer other nests than were successfully hatched eggs, and possible explanations are given.Incubation lasts about 30–31 days, a week longer than in most terns; both sexes incubate.Broken eggshells are never removed by the adults. Instead, after 2–3 days, the chicks leave the nest permanently to join a creche that roams freely about the immediate vicinity of the colony. Chicks remain in the creche for about 25–30 days, leaving it at fledging, approximately 30 days after hatching.While in the creche, chicks are normally fed only by their parents, who probably recognise them both vocally and visually, using the extensive variation in voice and colour of chicks characteristic of the species.Sandvicensis acuflavidachicks also are highly variable, and join Royal creches, adults of both species attending. Variation also occurs in Royals' juvenal plumage, and seems associated with extended parental care.Feeding adults normally wander up to 40 km from their colony, and this probably facilitates the intercolonial exchange of breeding birds we recorded. They feed inshore, in shallow waters, taking small fish by dives which do not go below the surface. They regularly take small soft‐shell crabs in this way, and frequently water‐skim like skimmersRynchopsspp., sometimes capturing food while doing so. A relationship between crab capture and water‐skimming is established for the first time, and water‐skimming in non‐feeding contexts is mentioned.Besides the quadruped predators which they normally avoid by fleeing the colony site, Royals have no known predators beyond the egg stage. Eggs, although not chicks, are readily taken by Laughing Gulls. Relationships between the two species are discussed, emphasising their const

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00832.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryThe fishing ability of first‐winter and older Sandwich Terns was compared at foraging sites used by both age‐groups on the coast of Sierra Leone between January and March 1970 when first‐winter birds were about 7–9 months old. The methods used for measuring various parameters of fishing ability are described. It was found that a significantly larger proportion of plunge dives by the older age‐group yielded prey although the difference between the two age‐groups was only slight.There were no major differences between the age‐groups in diving rates or in size of fish captured. Older birds tended to dive from higher than first‐winter birds.By driving shoals of small fish to the surface, predatory fish enhanced the fishing success of both age‐groups on certain days. Where man's beach seining operations yielded a superabundance of small fish near the tideline, these were captured equally well by both age‐groups.First‐winter birds were not seen being fed by older birds, and although food‐begging behaviour was observed once in late January it is clear that the first‐winter birds were self‐sufficient for food by the time this study was made.Some implications of the observed differences in fishing success are discussed. It is suggested that, after fledging, Sandwich Terns gradually gain the judgment and skill necessary to dive profitably from increasing heights and so learn to exploit prey in a greater range of wa

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00833.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryOver a three‐year period, 917 eggs from 27 females were collected from a captive colony of African Village WeaverbirdsPloceus c. cucullatus.A study was made of egg‐laying and incubation behaviour, clutch characteristics and egg recognition.Fifteen yearling females laid their first clutches at a mean age of 348 days after hatching. The mean clutch‐size was 2.26 in adults and 1.68 in yearlings. The mean clutch replacement interval was 6.6 days in adults and 7.4 days in yearlings with an absolute minimum of 4 days. Eggs were laid at intervals of from 24 to 26 hours beginning usually 2–3 hours after dawn.The eggs laid by this species vary in ground colour and pattern of spotting between different females, but egg pigmentation is constant for each individual bird. The results of 322 egg‐replacement tests showed that an individual female could recognise her own egg type and would eject from the nest eggs differing markedly from her own. The incidence of rejection was proportional the degree of difference between the eggs. The possible implications for parasitism by the Didric CuckooChrysococcyx cupriusare

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00834.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SummaryThe egg white proteins of the large ratites (Struthio, Casuarius, Dromaius, Rhea), the kiwis (Apteryx) and several tinamous (Tinamidae) were compared with one another and representatives of several other groups of birds using the technique of isoelectric focusing in acrylamide gel. The tryptic peptides of the ovalbumins of the same groups were compared by thin‐layer electrophoresis. The results indicate that the large ratites are more closely related to one another than any one of them is to any other living bird; that the kiwis are not closely related to any of the other groups with which they were compared; and that the tinamous are not closely related to any of the large ratites but may be distantly related to the Galliforme

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00835.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00836.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00837.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00838.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00839.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1972.tb00840.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY