Present address: Alberta Sustainable Resource Development, Fish and Wildlife Division, 100-3115 12 St. NE, Calgary, AB, Canada, T2E 7J2.
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Phenotypic effects on survival of neonatal northern watersnakes Nerodia sipedon
Article first published online: 19 JAN 2005
DOI: 10.1111/j.1365-2656.2005.00919.x
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How to Cite
KISSNER, K. J. and WEATHERHEAD, P. J. (2005), Phenotypic effects on survival of neonatal northern watersnakes Nerodia sipedon. Journal of Animal Ecology, 74: 259–265. doi: 10.1111/j.1365-2656.2005.00919.x
Publication History
- Issue published online: 19 JAN 2005
- Article first published online: 19 JAN 2005
- Received 27 February 2004; accepted 30 July 2004
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Keywords:
- neonate;
- Nerodia sipedon;
- optimal offspring size;
- phenotypes;
- survival
Summary
- 1Understanding the trade-off females make between offspring size and number requires knowing how neonatal size, and traits associated with size, affect survival.
- 2We studied neonatal survival in the northern watersnake Nerodia sipedon in outdoor enclosures with artificial hibernation sites.
- 3From a total of 950 neonates from 77 litters collected over 3 years, we found a survival rate of 65% between birth and hibernation and 47% during hibernation. Estimated survival from birth to the end of hibernation was 31%, comparable with indirect estimates for free-living watersnakes.
- 4Consistent with the ‘bigger is better’ hypothesis, larger neonates and neonates heavier relative to their body length were more likely to survive both the pre-hibernation and hibernation periods.
- 5Survival in the pre-hibernation period also decreased with the duration of that period and varied among years.
- 6Survival during hibernation was higher in warmer winters. Mass change prior to hibernation did not affect survival during hibernation.
- 7These results suggest that an optimal reproductive strategy should exist for female watersnakes, producing a ‘consensus’ among females on the optimal size for offspring. This expectation stands in stark contrast to the pronounced variation in offspring size observed both within and among litters.