FURTHER NOTES ON THE BREEDING BIOLOGY OF THE SWIFT APUS APUS
Summary. The period when Swifts have young in the nest probably corresponds, in general, with the season when their food is most abundant. The start of the clutch may be held up by bad weather, which influences laying five days later. The eggs are usually laid at 2‐day intervals, a 3‐day interval be...
| Published in: | Ibis |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1956
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| Online Access: | http://dx.doi.org/10.1111/j.1474-919x.1956.tb01452.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1956.tb01452.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1956.tb01452.x |
| Summary: | Summary. The period when Swifts have young in the nest probably corresponds, in general, with the season when their food is most abundant. The start of the clutch may be held up by bad weather, which influences laying five days later. The eggs are usually laid at 2‐day intervals, a 3‐day interval being commoner in cold than warm weather. The proportion of clutches consisting of three rather than two eggs is highest at the start of the breeding season and progressively declines. It is also, and independently, reduced by cold weather. All the young are normally raised in broods of one every year, in broods of two except in very wet summers, in broods of three only in fine summers. In wet as compared with fine summers, nestling periods are longer, nestling weights are lower and the wings grow more slowly. Brood‐size has a negligible influence on the nestling period, nestling weight and wing‐length in fine summers, but a marked influence in wet summers. |
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