GROWTH, AND ANNUAL CYCLES IN WEIGHTS, PLUMAGES AND REPRODUCTIVE ORGANS OF GOOSANDERS IN EASTERN CANADA
SUMMARY A study of Goosanders, in connection with a Fisheries shooting programme on Cape Breton Island, has shown the pattern of growth in young birds, and of plumage and other annual cycles in fully grown birds. The plumage cycles show little difference between the sexes in the first year, with mal...
| Published in: | Ibis |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1971
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| Online Access: | http://dx.doi.org/10.1111/j.1474-919x.1971.tb05122.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1971.tb05122.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1971.tb05122.x |
| Summary: | SUMMARY A study of Goosanders, in connection with a Fisheries shooting programme on Cape Breton Island, has shown the pattern of growth in young birds, and of plumage and other annual cycles in fully grown birds. The plumage cycles show little difference between the sexes in the first year, with males thereafter moulting about one month earlier than females. Virtually no moult occurs from January to March, nor in adults during April to mid‐June, in this area. Weights and measurements permit ageing of flightless young of known sex, and sexing of all fully grown birds, but they do not distinguish first‐year from older individuals. Gross examination suggests that males in the second calendar year (11 to 12 months old) may come into reproductive condition, at least under conditions of year‐round hunting. Variations in annual moult cycles may be due to differing geographic origin of the birds; I suggest that birds killed in other Goosander shooting programmes should be used for comparative studies parallel to this one. |
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