A comment on the age at onset of breeding of male Weddell seals ( Leptonychotes weddellii )
In an otherwise valuable contribution, Bartsh et al. (S.S. Bartsh, S.D. Johnston, and D.B. Siniff. 1992. Can. J. Zool. 70: 680 – 692) reached the conclusion that the youngest age at which male Weddell seals (Leptonychotes weddellii) become sexually active in their breeding colonies was 7 years, with...
| Published in: | Canadian Journal of Zoology |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1997
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| Online Access: | http://dx.doi.org/10.1139/z97-021 http://www.nrcresearchpress.com/doi/pdf/10.1139/z97-021 |
| Summary: | In an otherwise valuable contribution, Bartsh et al. (S.S. Bartsh, S.D. Johnston, and D.B. Siniff. 1992. Can. J. Zool. 70: 680 – 692) reached the conclusion that the youngest age at which male Weddell seals (Leptonychotes weddellii) become sexually active in their breeding colonies was 7 years, with first breeding likely, on average, in year 8. While plausible, this conclusion was based on only 5 seals of known age and 9 seals whose age was estimated from a length – age regression model. In addition to methodological problems with the regression model used by Bartsh et al., its application to a sample of known-age male Weddell seals correctly predicted the ages of only 25% of seals in the range of ages likely to include the age at social maturity, and was commonly off by 3 – 5 years and more. The age at onset of sexual activity of male Weddell seals cannot be determined from that analysis. |
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