Bayesian Methods for Estimating Animal Abundance at Large Spatial Scales Using Data from Multiple Sources

  • Soumen Dey
  • Mohan Delampady
  • Ravishankar Parameshwaran
  • N. Samba Kumar
  • Arjun Srivathsa
  • K. Ullas Karanth


Estimating animal distributions and abundances over large regions is of primary interest in ecology and conservation. Specifically, integrating data from reliable but expensive surveys conducted at smaller scales with cost-effective but less reliable data generated from surveys at wider scales remains a central challenge in statistical ecology. In this study, we use a Bayesian smoothing technique based on a conditionally autoregressive (CAR) prior distribution and Bayesian regression to address this problem. We illustrate the utility of our proposed methodology by integrating (i) abundance estimates of tigers in wildlife reserves from intensive photographic capture–recapture methods, and (ii) estimates of tiger habitat occupancy from indirect sign surveys, conducted over a wider region. We also investigate whether the random effects which represent the spatial association due to the CAR structure have any confounding effect on the fixed effects of the regression coefficients.


Capture–recapture survey CAR model Hierarchical Bayes Model selection Occupancy survey Spatial confounding 



We are extremely grateful to the associate editor and two anonymous referees for bringing to our attention some very relevant and important literature, as well as for helping us improve the presentation. We thank James Nichols and Arjun Gopalaswamy for very useful comments and suggestions.


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Copyright information

© International Biometric Society 2017

Authors and Affiliations

  1. 1.Statistics and Mathematics UnitIndian Statistical Institute, Bangalore CentreBengaluruIndia
  2. 2.Centre for Wildlife StudiesBengaluruIndia
  3. 3.Wildlife Conservation Society, India ProgramBengaluruIndia
  4. 4.School of Natural Resources and Environment, University of FloridaGainesvilleUSA
  5. 5.Department of Wildlife Ecology and ConservationUniversity of FloridaGainesvilleUSA
  6. 6.National Centre for Biological Sciences, Tata Institute of Fundamental ResearchBengaluruIndia

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