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Biodiversity and Conservation

, Volume 21, Issue 6, pp 1589–1606 | Cite as

Subpopulation range estimation for conservation planning: a case study of the critically endangered Cross River gorilla

  • Sarah C. Sawyer
Original Paper

Abstract

Measuring and characterizing the area utilized by a population or species is essential for assessment of conservation status and for effective allocation of habitat to ensure population persistence. Yet population-level range delineation is complicated by the variety of available techniques coupled with a lack of empirical methods to compare the relative value of these techniques. This study assesses the effect of model choice on resulting subpopulation range estimation for the critically endangered and patchily distributed Cross River gorilla, and evaluates the conservation conclusions that can be drawn from each model. Models considered range from basic traditional approaches (e.g. minimum convex polygon) to newer home range techniques such as local convex hull (LoCoH). Overlap analysis comparing sub-sampled to complete data sets are used to evaluate the robustness of various modeling techniques to data limitations. Likelihood cross validation criterion is employed to compare core range model performance. Results suggest that differing LoCoH models produce similar range estimates, are robust to data requirements, provide a good fit for core habitat estimation, and are best able to detect unused habitat within the subpopulation range. LoCoH methods may thus be useful for studies into habitat selection and factors limiting endangered species distributions. However, LoCoH models tend to over-fit data, and kernel methods may provide similar information about animal space use while supporting protection of larger swaths of critical habitat. Subpopulation range analyses for conservation/management planning should therefore explore multiple modeling techniques, and employ both qualitative and quantitative assessments to select the best models to inform decision making for species of conservation concern.

Keywords

Conservation planning Cross River gorilla Cross validation criterion Home range analysis Local convex hull 

Notes

Acknowledgments

Financial support for this project was provided by United States Fish and Wildlife Service and two grants from the Rocca scholars program (UC Berkeley). Logistical support was generously provided by The Wildlife Conservation Society, Cameroon and the North Carolina Zoo. The author was supported by a Chancellor’s fellowship from the University of California, Berkeley. A debt of gratitude is owed particularly to Justin Brashares, Aaron Nicholas, Ymke Warren, Richard Bergl, Okon Felix, Eyong Pius, the WCS Limbe staff, the Brashares lab group, and the village of Nga for all of their support. Thanks also to Wayne Getz and two anonymous reviewers for aid in improving the manuscript. This research was conducted with the permission of the Ministry of Forests and Wildlife and the Ministry of Scientific and Technical Research.

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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.Department of Environmental Science, Policy and ManagementUniversity of CaliforniaBerkeleyUSA

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