Journal article

Simultaneous-count models to estimate abundance from counts of unmarked individuals with imperfect detection

Gerard Edward Ryan, Emily Nicholson, Jonathan C Eames, Thomas NE Gray, Robin Loveridge, Simon P Mahood, Phearun Sum, Michael A McCarthy

CONSERVATION BIOLOGY | WILEY | Published : 2019

Abstract

We developed a method to estimate population abundance from simultaneous counts of unmarked individuals over multiple sites. We considered that at each sampling occasion, individuals in a population could be detected at 1 of the survey sites or remain undetected and used either multinomial or binomial simultaneous-count models to estimate abundance, the latter being equivalent to an N-mixture model with one site. We tested model performance with simulations over a range of detection probabilities, population sizes, growth rates, number of years, sampling occasions, and sites. We then applied our method to 3 critically endangered vulture species in Cambodia to demonstrate the real-world appli..

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Grants

Awarded by ARC Centre of Excellence for Environmental Decisions


Funding Acknowledgements

This research was funded by the ARC Centre of Excellence for Environmental Decisions (CE1101014). We thank J. J. Lahoz-Monfort, G. Guillera-Arroita, W. Morris, J. Baumgartner, H. Kujala, and C. Visintin for support and discussion. The Critical Ecosystems Partnership Fund supports the ongoing work of the Cambodia Vulture Conservation Project. The Critical Ecosystem Partnership Fund is a joint initiative of l'Agence Francaise de Developpement, Conservation International, the GlobaThe Critical Ecosystems Partnership Fund supports the ongoing work of the Cambodia Vulture Conservation Project. Tl Environment Facility, the Government of Japan, the MacArthur Foundation, and the World Bank. We especially thank all those who spent many tiresome years in the field counting vultures and those who commit funds long-term to this work.