Abstract
Many ecological theories and species conservation programmes rely on accurate estimates of population density. Accurate density estimation, especially for species facing rapid declines, requires the application of rigorous field and analytical methods. However, obtaining accurate density estimates of carnivores can be challenging as carnivores naturally exist at relatively low densities and are often elusive and wide-ranging. In this study, we employ an unstructured spatial sampling field design along with a Bayesian sex-specific spatially explicit capture-recapture (SECR) analysis, to provide the first rigorous population density estimates of cheetahs (Acinonyx jubatus) in the Maasai Mara, Kenya. We estimate adult cheetah density to be between 1.28 ± 0.315 and 1.34 ± 0.337 individuals/100km2 across four candidate models specified in our analysis. Our spatially explicit approach revealed ‘hotspots’ of cheetah density, highlighting that cheetah are distributed heterogeneously across the landscape. The SECR models incorporated a movement range parameter which indicated that male cheetah moved four times as much as females, possibly because female movement was restricted by their reproductive status and/or the spatial distribution of prey. We show that SECR can be used for spatially unstructured data to successfully characterise the spatial distribution of a low density species and also estimate population density when sample size is small. Our sampling and modelling framework will help determine spatial and temporal variation in cheetah densities, providing a foundation for their conservation and management. Based on our results we encourage other researchers to adopt a similar approach in estimating densities of individually recognisable species.
Highlights
IntroductionCounting Cats: Spatially Explicit Population Estimate of Cheetah and conservation
Obtaining accurate estimates of densities is central to our understanding of the spatio-temporal dynamics of animal populations and provides the foundation for effective wildlife managementPLOS ONE | DOI:10.1371/journal.pone.0153875 May 2, 2016Counting Cats: Spatially Explicit Population Estimate of Cheetah and conservation
We aim to provide the first rigorous estimate of the cheetah population in the Maasai Mara National Reserve and the surrounding wildlife conservancies using a sex-specific spatially explicit capture-recapture (SECR) modelling approach based on field sampling via direct sightings of individual cheetah using an unstructured spatial sampling design
Summary
Counting Cats: Spatially Explicit Population Estimate of Cheetah and conservation. This is especially the case for large carnivores as many species have undergone drastic declines over the last few decades [1]. Indirect methods such as spoor surveys are commonly used to estimate densities [3, 4]. To minimise cost and resources, such surveys are commonly conducted within a relatively small area and extrapolated across a much larger area using index-calibration methods. This approach is inaccurate as the variations of detection probability are left unaccounted for [5]. In light of the consequences of these inaccuracies it is being recognised that more robust ways of estimating population parameters are required [6]
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