Comments on Calverley and Boag's (1977) hypothesis on displaced ducks and an evolutionary alternative
Calverley and Boag's (1977. Can. J. Zool. 55: 1242–1251) analysis of reproductive potential in parkland- and arctic-nesting mallards and pintails does not support their conclusion that parkland-displaced birds breed in the arctic with reduced reproductive output. The different clutch sizes in t...
| Published in: | Canadian Journal of Zoology |
|---|---|
| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1978
|
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/z78-303 http://www.nrcresearchpress.com/doi/pdf/10.1139/z78-303 |
| Summary: | Calverley and Boag's (1977. Can. J. Zool. 55: 1242–1251) analysis of reproductive potential in parkland- and arctic-nesting mallards and pintails does not support their conclusion that parkland-displaced birds breed in the arctic with reduced reproductive output. The different clutch sizes in the two areas may result from selection for a smaller clutch at higher latitudes because of the greater energy expense of travel; however, individual fitness may be similar in parkland- and arctic-nesting populations if the advantage of a large clutch at lower latitudes is offset by higher levels of competition and predation. |
|---|