BREEDING SEASONS OF THE HOUSE SPARROW AND TREE SPARROW PASSER SPP. AT OXFORD

The breeding season of P. domesticus in 1961 and from 1963 to 1964. at Oxford began in April and ended in early August; that of P. montunus began slightly later and ended slightly earlier and this species also laid fewer clutches. In P. domesticus laying birds fell into two groups, namely "early-" and "late-starters", which, from a comparison with data obtained from birds of known age, appeared to be mostly females two or more years old, and females one year old, respectively. In P. montanus , however, it appeared that birds of all ages were beginning breeding at about the same time in the season. The laying of first clutches of the early-starting birds of P. domesticus and of the earlier starting members of the one group of P. montanus was correlated with the prevailing air temperature; it is estimated that P. domesticus began its laying at slightly lower air temperatures than P. montunus . It is suggested that laying is adapted to begin at a particular air temperature because at lower temperatures the adult would have insufficient energy available to produce and incubate a clutch.     

黄海车牛山岛白腰雨燕的食性分析及其在巢区活动的雷达测定

食性分析结果表明,白腰雨燕Apus P.pacificus的食物概为昆虫,隶属于9个目。雷达的测定证实它们在巢区的活动和气候、昆虫有着密切的联系。对它们活动规律的研究,必将有助于探索空中昆虫的迁移、扩散生态学特性以及昆虫在分布区内的动态规律。     

黄海车牛山岛白腰雨燕的繁殖习性及种群动态

本文为作者于1980—1981年对黄海车牛山岛白腰雨燕Apuspacificus pacificus (Latham)的初步研究。内容包括对繁殖习性的观察;对繁殖周期、卵孵化率、雏鸟成活串以及出生率等的统计。并对海岛生态环境下白腰雨燕种群数量的变动及其影响因素,作初步探讨。     

NESTLING SURVIVAL AND NESTLING WEIGHTS IN THE HOUSE SPARROW AND TREE SPARROW PASSER SPP. AT OXFORD

Nestling survival and nestling weights in P. domesticus and P. montanus were studied in 1961 and 1963–64 at Oxford. This paper concludes a study of factors influencing the reproductive rate. Taking all losses into account, P. domesticus reared an average of 1^.6 nestlings per brood (45%) and P. montanus 2.7 nestlings per brood (59%). About a third of all broods of both species failed completely to survive the nestling period. In P. domesticus these failures were most numerous in the middle part of the breeding season and are attributed to nutritional deficiencies derived from unsuitable food provided as a consequence of a seasonal food shortage, but in P. montanus complete brood failures occurred mostly in the second half of the nestling period and are attributed to predation. 43 broods of P. domesticus and one brood of P. montanus were weighed daily. Those of P. domesticus were classified as (1) successful broods—in these some nestlings died in the larger brood-sizes, apparently through starvation; (2) long-lived unsuccessful broods—in these the nestlings died at intervals and failure was attributed to nutritional deficiencies; and (3) short-lived unsuccessful broods. A slight decrease in the weights of nestlings in successful broods at the end of the nestling period is attributed to the utilization of insulating fat facilitated by the completion of the feather covering. Nestlings of both species left the nest at 88–89% of the adult weight. Taking all “successful” broods together, the percentage survival rates on nestling day 13¹/₂ (day of hatching = day ¹/₂) in P. domesticus were 81–82% in b/2–3, 70% in b/4 and 56% in b/5 (a situation paralleled in this respect by P. hispaniolensis), but in P. montanus they were c. 82% in all brood-sizes. Hence, in P. domesticus b/4 probably gave rise to the largest number of nestlings reared per brood, while in P. montanus most nestlings were produced by the largest brood-size. Weighings of many broods on day 13¹/₂ showed two trends in the weight of the nestlings: (1) in both species the weight of the nestling decreased as the number of survivors from each initial brood-size decreased; (2) between successive initial brood-sizes the weight of the nestling of P. domesticus decreased with increasing brood-size but in P. montanus there was no change. The losses in the larger broods of P. domesticus occurred mostly in the first half of the nestling period—apparently in association with the asynchronous hatching of the eggs and as a consequence of the limitation on the feeding frequency of the adults. Nestling survival was lowest in the larger broods in the middle of the breeding season and contrasted with the mid-season increase in mean clutch-size. It is suggested that in the study area there was a (possibly unnatural) shortage of food suitable for nestlings in the middle of the season. It is suggested that in P. domesticus the unexpectedly low feeding frequencies of the adults with large broods, apparently causing their low survival rates, may be an adaptation evolved to obtain the maximum amount of food in the presence of other adults which would be attracted to a food source by higher rates of activity. The breeding success calculated from data derived from the whole of this study was 35% for P. domesticus and 49% for P. montanus (2.9 and 3.9 nestlings per breeding pair per year respectively). It is suggested that the population of P. domesticus was much closer to a critical limiting factor, e.g. food supply, than that of P. montanus. This may account for the striking differences between the two species in their nestling survival rates and their nestling weights in relation to brood-size; in particular, the success of the larger broods of P. montanus may have been a temporary phenomenon.     

CLUTCH-SIZE, INCUBATION AND HATCHING SUCCESS IN THE HOUSE SPARROW AND TREE SPARROW PASSER SPP. AT OXFORD

Clutch-size, incubation and hatching success were studied in P. domesticus and P. montanus in 1961 and 1963–64 at Oxford. The most frequent clutch-size was four eggs in P. domesticus and five eggs in P. montanus . With one exception, colonies of P. domesticus showed no significant annual or local variations in its mean clutch-size; in P. montanus , however, there were significant annual variations in the mean clutch-size. Both species showed a seasonal increase followed by a decrease in their mean clutch-sizes.
Partial incubation occurred during the laying period of the clutch; sufficient incubation for continuous development of the embryo was apparently achieved when the last egg had been laid in clutches of two and three eggs in P. domesticus and in clutches of four eggs in P. montanus , but when the penultimate egg had been laid in larger clutches of both species. On average, hatching in P. domesticus occurred more or less synchronously in all eggs in clutches of two and three eggs, and in all eggs except the last one laid in larger clutches; the last egg in the larger clutches hatched up to a day after the others. It is suggested that this pattern of hatching was brought about by the pattern of incubation during the laying period.
P. domesticus had a lower hatching success than P. montanus , probably because fewer of its eggs were fertile.