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Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population.

Publication ,  Journal Article
Arso Civil, M; Cheney, B; Quick, NJ; Islas-Villanueva, V; Graves, JA; Janik, VM; Thompson, PM; Hammond, PS
Published in: Ecology and evolution
January 2019

Understanding the drivers underlying fluctuations in the size of animal populations is central to ecology, conservation biology, and wildlife management. Reliable estimates of survival probabilities are key to population viability assessments, and patterns of variation in survival can help inferring the causal factors behind detected changes in population size. We investigated whether variation in age- and sex-specific survival probabilities could help explain the increasing trend in population size detected in a small, discrete population of bottlenose dolphins Tursiops truncatus off the east coast of Scotland. To estimate annual survival probabilities, we applied capture-recapture models to photoidentification data collected from 1989 to 2015. We used robust design models accounting for temporary emigration to estimate juvenile and adult survival, multistate models to estimate sex-specific survival, and age models to estimate calf survival. We found strong support for an increase in juvenile/adult annual survival from 93.1% to 96.0% over the study period, most likely caused by a change in juvenile survival. Examination of sex-specific variation showed weaker support for this trend being a result of increasing female survival, which was overall higher than for males and animals of unknown sex. Calf survival was lower in the first than second year; a bias in estimating third-year survival will likely exist in similar studies. There was some support first-born calf survival being lower than for calves born subsequently. Coastal marine mammal populations are subject to the impacts of environmental change, increasing anthropogenic disturbance and the effects of management measures. Survival estimates are essential to improve our understanding of population dynamics and help predict how future pressures may impact populations, but obtaining robust information on the life history of long-lived species is challenging. Our study illustrates how knowledge of survival can be increased by applying a robust analytical framework to photoidentification data.

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Published In

Ecology and evolution

DOI

EISSN

2045-7758

ISSN

2045-7758

Publication Date

January 2019

Volume

9

Issue

1

Start / End Page

533 / 544

Related Subject Headings

  • 4102 Ecological applications
  • 3104 Evolutionary biology
  • 3103 Ecology
  • 0603 Evolutionary Biology
  • 0602 Ecology
 

Citation

APA
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Arso Civil, M., Cheney, B., Quick, N. J., Islas-Villanueva, V., Graves, J. A., Janik, V. M., … Hammond, P. S. (2019). Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population. Ecology and Evolution, 9(1), 533–544. https://doi.org/10.1002/ece3.4772
Arso Civil, Mònica, Barbara Cheney, Nicola J. Quick, Valentina Islas-Villanueva, Jeff A. Graves, Vincent M. Janik, Paul M. Thompson, and Philip S. Hammond. “Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population.Ecology and Evolution 9, no. 1 (January 2019): 533–44. https://doi.org/10.1002/ece3.4772.
Arso Civil M, Cheney B, Quick NJ, Islas-Villanueva V, Graves JA, Janik VM, et al. Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population. Ecology and evolution. 2019 Jan;9(1):533–44.
Arso Civil, Mònica, et al. “Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population.Ecology and Evolution, vol. 9, no. 1, Jan. 2019, pp. 533–44. Epmc, doi:10.1002/ece3.4772.
Arso Civil M, Cheney B, Quick NJ, Islas-Villanueva V, Graves JA, Janik VM, Thompson PM, Hammond PS. Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population. Ecology and evolution. 2019 Jan;9(1):533–544.
Journal cover image

Published In

Ecology and evolution

DOI

EISSN

2045-7758

ISSN

2045-7758

Publication Date

January 2019

Volume

9

Issue

1

Start / End Page

533 / 544

Related Subject Headings

  • 4102 Ecological applications
  • 3104 Evolutionary biology
  • 3103 Ecology
  • 0603 Evolutionary Biology
  • 0602 Ecology