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Endangered Species Research

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ESR 29:255-270 (2016)  -  DOI:

Factors influencing heterogeneity in female reproductive success in a Critically Endangered population of bottlenose dolphins

T. E. Brough1,*, S. Henderson1,2, M. Guerra1, S. M. Dawson1

1Marine Mammal Research Group, Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand
2Department of Biology, Tacoma Community College, 6501 South 19th Street, Tacoma, Washington 98466, USA
*Corresponding author:

ABSTRACT: For threatened species or populations, variation in reproductive success among females may be explicitly linked with vulnerability to extinction. Thus, an understanding of factors that may cause variability in reproductive success is important. The population of bottlenose dolphins in Doubtful Sound, New Zealand, has a recent history of rapid population decline and low calf survival rates. A previous study has shown high variability in calf survival among multiparous females. This study addresses the factors that seem most important in explaining variation in calf survival and thus reproductive success among females in this population. Reproductive data were sourced from a long-term photo-identification dataset, which allowed tracking the fate of 49 calves born into the population between 1995 and 2012. General linear mixed models combined with model averaging were used to assess how birth timing, maternal size, age and potential anthropogenic impacts contributed to variation in calf survival. Models show that a female’s size and her ability to give birth at an optimum time in the calving season are significant predictors of calf survival to an age of 1 and 3 yr. This is the first study to demonstrate how birth timing and mother size are correlated with female reproductive success in a cetacean species. These results confirm the importance of demographic stochasticity and reproductive heterogeneity in small, threatened marine mammal populations.

KEY WORDS: Reproductive success · Reproductive heterogeneity · Survival · Bottlenose dolphin

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Cite this article as: Brough TE, Henderson S, Guerra M, Dawson SM (2016) Factors influencing heterogeneity in female reproductive success in a Critically Endangered population of bottlenose dolphins. Endang Species Res 29:255-270.

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