摘要:

Prigogine's NightjarCaprimulgus prigogineiis described from a single skin collected in 1955 in Itombwe, eastern Zaïre. The species is unknown in life. Because of its distinct morphology: rather stiff feathers, small tail/wing proportion, broad head, short rictal bristles and its speckled plumage, it is considered to be without close relatives

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01054.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Effects of a change of diet on growth rates and fledging sizes of Yellow‐eyed PenguinsMegadyptes antipodeswere examined at two breeding areas on South Island, New Zealand, during two breeding seasons. An adverse change in diet was observed in the second season. Evidence for this included depressed growth rates of weight, differential growth of weight and most morphometric parameters between one‐ and two‐chick nests in the second season, lower fledging weights, lower adult body weights, delayed moult, higher chick mortality and higher adult mortality during moult. The change in diet is suggested as being from one including oil‐rich prey species, to one of oil‐poor species.Growth rates of first‐ and second‐hatched chicks, and of survivors and non‐survivors within a brood were not significantly different in either season, and growth rates of two‐chick broods were only slightly slower than one‐chick broods for some parameters in the second season. This, and synchronous hatching of chicks, equal egg‐size and lack of sibling competition during feeding sessions, suggests that brood reduction is not an option available to Yellow‐eyed Penguins, and that food supply may not be a limiting factor in the majority of breeding seasons.Few changes in growth rates of morphometric parameters at either breeding area, and similar absolute sizes at fledging, indicate that slowing of growth rates of morphometric parameters only occurs when feeding conditions are so bad as to result in mortality and that, although fledging periods may be longer, patterns of development remai

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01055.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

New Zealand SnipeCoenocorypha aucklandica were studied over six breeding seasons on the Snares Islands. The study area (7.5 ha) held about 20 pairs at a density of 3.2 ± O.5 pairs/ha, plus 5 to 25 nonterritorial birds. Most matings were monogamous but simultaneous polygyny was recorded in one territory (by two different males) in four consecutive seasons. Males courtship fed females before egg‐laying. The typical clutch was two eggs, laid three days apart. Incubation was shared equally by the sexes in monogamous pairs and took 22 days. Some females with polygynous mates attempted to incubate unaided, which took about 38 days. Broods were split at hatching, with the male caring for the first chick to leave the nest. Chicks were fed by adults for at least 41 days, and did not become independent until about 65 days old. Growth rates were slow compared to Common SnipeGallinago gallinagoand full plumage took about 54 days to attain. No pairs were double‐brooded but 43% of pairs that failed during incubation or early chick‐rearing renested together. Some breeders of both sexes who had lost their dependent chick bred a second time with a new mate while their first mate continued rearing the surviving chick (sequential polygyny and polyandry). Hatching success was 80%, and fledging success was 48%. Each pair produced, on average, O.6 fledglings per year.Chatham Island SnipeC. pusillawere studied on Rangatira Island during the 1983–84 breeding season. Breeding density was about 5.6 pairs/ha. The breeding system was very similar to that for C.aucklandicabut chicks became independent at about 41 days old. Hatching success was 89%.Compared to Common Snipe,Coenocoryphasnipes occurred at high densities, had courtship feeding, large eggs, a long interegy interval, a small clutch, shared incubation and a long incubation period. Nest desertion rates were high, but overall hatching success was also high, chick growth rates were slow, there was a long period of chick dependence and a long relaying interval following nest failure or chick loss. Survival rates of both adults and chicks were high. These differences are attributed to the absence of predation, and to intense intraspecific competition for food in a stable env

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01056.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The duration and rate of yolk deposition in the formation of avian eggs are species specific and are apparently fixed characteristics. We determined these properties for eggs from 40 species of marine birds. The mass of yolk laid down daily during rapid yolk deposition in the ovary was calculated and used to construct and compare yolk enlargement curves for each species. The spectrum of curves are all best fitted by simple second‐order polynomial regression equations, with the very rapidly enlarging yolks of Alcidae at one extreme and the slow‐forming eggs of Procellariiformes at the other. Calculated daily energy allocation to yolk deposition during the last, and most demanding, phase of yolk formation ranged from 3% to 44% of standard metabolic rate, considerably lower than other estima

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01057.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The breeding of Tengmalm's OwlAegolius funereuswas studied at Umeå, Sweden, during the 1984–85. Mean clutch‐size was one egg larger in 1984 than in 1985 despite the later laying in 1984. The difference in clutch‐size was related to a better food supply in 1984. Daily weight increase of females during the prelaying period showed a high negative correlation with laying date in 1985, and a high positive correlation with clutch‐size independently of laying date in 1984–85. This suggested that food eaten before and during laying had a great and direct influence on both laying date and clutch‐size. Many females increased in weight during laying and most others decreased only moderately (relative to egg weight), suggesting that body reserves were not a main source for egg production.Late breeding females were provided with extra food during the prelaying and laying periods in 1985. Fed females weighed more, bred eight days earlier and laid one more egg than controls. At the same laying dates in mid season, and after heavy snow‐fall, clutch‐size and female weight were larger in the fed birds than in controls, but this was not so near the end of the laying season. Although the earliest of the fed late breeders weighed more, and probably were less restricted by food availability just before or during laying, they did not lay more eggs than did early breeders. This result suggested some limitation on clutch‐size that could not be overcome by the supplementary feeding. Weights of females during laying did not show any consistent relationship with clutch‐size during successive laying date intervals, suggesting that clutch‐size was not directly rel

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01058.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Variation in clutch‐size among New World passerine birds was analysed with respect to four variables: body‐mass, geographic latitude, the frequency of nest predation, and the structure of the nest. Data were analysed separately by averaging traits at three taxonomic levels: species, genus, and subfamily. Allometric scaling with body‐mass did not account for significant variation in clutch‐size regardless of the taxonomic level of analysis. Latitudinal effects on clutch‐size were highly significant at all taxonomic levels. For species building small‐pensile nests and open‐cup nests, nest predation had a significant partial effect on clutch‐size, with latitude held constant. When nest predation and latitude were held constant, clutch‐size was significantly different among species building small‐pensile nests, open‐cup nests, and domed nests. These results suggest that New World passerine clutch‐size is related to at least three variables: latitudinal effects, nest predat

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01059.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Daily energy expenditure of WheatearsOenanthe oenantheduring the brood rearing period was measured using the doubly‐labelled water technique. The average daily metabolic rate (ADMR) (± 1 s.d.) for 24 individuals was 6.24 ± 1.17 cm3CO2/g/h, which corresponds to 95.3 ± 17.0 kJ/day (RQ = 0.75) for a bird of average mass (24.3 g).There were no significant differences in daily energy expenditure between the sexes, nor between first‐year and older birds. Individual males with longer tarsi had lower ADMR but raised larger broods. The ADMR increased at lower ambient temperatures, but this effect disappeared when the positive correlation with rainfall was taken into account. There was no relationship between the natural brood‐size and parental daily energy expenditure. A positive correlation between ADMR and the time spent hopping and pecking suggests that foraging activity may account for some of the variability between individuals. The daily change in body‐mass was not related to either the individual's age or its sex, and overall was not correlated with the level of daily energy expenditure. For birds examined on the same day, individuals with a higher ADMR had a greater loss of body‐mass, which appears to be a high risk strategy. However, Wheatears also exhibited an ability to increase body‐mass in conjunction with a drop in their daily ener

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01060.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The reproductive interactions of the Shiny CowbirdMolothrus bonariensis, a brood parasite, and the Yellow‐hooded BlackbirdAgelaius icterocephalus, a host of the cowbird, were studied In Trinidad, West Indies. We gathered information on the breeding biology of the Shiny Cowbird and the Yellow‐hooded Blackbird, the frequency of use of the host species, and the effects of brood parasitism on host breeding success. Yellow‐hooded Blackbirds are polygynous for the most part; males build nests and attempt to attract females to lay in them by means of song and visual displays directed towards the nests. This behaviour probably makes it easy for cowbirds to locate breeding birds and their nests. Cowbird eggs were found in 153 of 377 (40–3 %) blackbird nests located before the nestling stage. Shiny Cowbird parasitism of the Yellow‐hooded Blackbird had little negative impact on host reproductive success, whereas predation accounted for the majority of nest failures. Vigilant nest defense by male blackbirds combined with colonial breeding apparently also minimized the extent of host egg damage and removal by cowbirds, and the parasitized and unparasitized nests were equally successful at producing blackbirds. Cowbirds most frequently parasitized the first or only nesting attempts in blackbird territories, and first or only nests were also successful more frequently than subsequ

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01061.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The efficiency of the analysis of faeces and flushes of the digestive tract was examined by feeding captive Garden WarblersSylvia borinand BlackcapsS. atricapillawith different food types (arthropods, fruits). Faecal analysis underestimated aphids; the analysis of flushes overestimated beetles and underestimated aphids and fruits. Correction factors to remove these biases are given. Flushing free‐living birds showed no noticeable effect on recapture rates and body mass. Methods of calculating the number of prey items from different fragments are evaluate

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01062.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Within the strongly polytypic Red CrossbillL. curvirostrathere are many reports of two or more ‘subspecies’ nesting sympatrically, without interbreeding. This 13‐year study examines one such case, in Scotland, where an endemic form is resident and another was thought to occur after irruptions from its main range in continental Europe. Both forms were present in the study area every year; sympatric breeding was proved in 9 years and probably occurred in the other four. There was no suggestion of interbreeding and the Scottish form should be treated as a separate species,L. scotica, the Scottish Crossbill. This is the only endemic species of bird in Britain and one of very few European endemics. The evolution of crossbills in Europe is discussed in the light of recent palynological evidence and the taxonomic status of the Parrot CrossbillL. pytyopsittacusis re‐e

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01063.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY