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

Mònica Arso Civil (Corresponding Author), Barbara Cheney, Nicola J. Quick, Valentina Islas-Villanueva, Jeff A. Graves, Vincent M. Janik, Paul M. Thompson, Philip S. Hammond

Research output: Contribution to journalArticle

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Abstract

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.

Original languageEnglish
Pages (from-to)533-544
Number of pages11
JournalEcology and Evolution
Volume9
Issue number1
Early online date19 Dec 2018
DOIs
Publication statusPublished - Jan 2019

Fingerprint

marine mammal
marine mammals
survival rate
gender
calves
Tursiops truncatus
population size
wildlife management
Scotland
anthropogenic activities
animals
environmental impact
population dynamics
life history
population trend
rate
viability
ecology
coasts
Biological Sciences

Keywords

  • calf survival
  • capture–recapture
  • mortality rate
  • population dynamics
  • sex-specific survival
  • Tursiops
  • PROTECTED AREAS
  • PREY ABUNDANCE
  • WHALES
  • TURSIOPS-TRUNCATUS
  • BOTTLE-NOSED DOLPHINS
  • GROUP-SIZE
  • capture-recapture
  • LIFE-HISTORY
  • TEMPORARY EMIGRATION
  • CAPTURE-RECAPTURE DATA
  • REPRODUCTIVE SUCCESS

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Nature and Landscape Conservation
  • Ecology

Cite this

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

Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population. / Arso Civil, Mònica (Corresponding Author); Cheney, Barbara; Quick, Nicola J.; Islas-Villanueva, Valentina; Graves, Jeff A.; Janik, Vincent M.; Thompson, Paul M.; Hammond, Philip S.

In: Ecology and Evolution, Vol. 9, No. 1, 01.2019, p. 533-544.

Research output: Contribution to journalArticle

Arso Civil, Mònica ; Cheney, Barbara ; Quick, Nicola J. ; Islas-Villanueva, Valentina ; Graves, Jeff A. ; Janik, Vincent M. ; Thompson, Paul M. ; Hammond, Philip S. / Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population. In: Ecology and Evolution. 2019 ; Vol. 9, No. 1. pp. 533-544.
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