Methodological approaches for estimating populations of the endangered dhole Cuon alpinus

PeerJ. 2022 Feb 22:10:e12905. doi: 10.7717/peerj.12905. eCollection 2022.

Abstract

Large carnivores are important for maintaining ecosystem integrity and attract much research and conservation interest. For most carnivore species, estimating population density or abundance is challenging because they do not have unique markings for individual identification. This hinders status assessments for many threatened species, and calls for testing new methodological approaches. We examined past efforts to assess the population status of the endangered dhole (Cuon alpinus), and explored the application of a suite of recently developed models for estimating their populations using camera-trap data from India's Western Ghats. We compared the performance of Site-Based Abundance (SBA), Space-to-Event (STE), and Time-to-Event (TTE) models against current knowledge of their population size in the area. We also applied two of these models (TTE and STE) to the co-occurring leopard (Panthera pardus), for which density estimates were available from Spatially Explicit Capture-Recapture (SECR) models, so as to simultaneously validate the accuracy of estimates for one marked and one unmarked species. Our review of literature (n = 38) showed that most assessments of dhole populations involved crude indices (relative abundance index; RAI) or estimates of occupancy and area of suitable habitat; very few studies attempted to estimate populations. Based on empirical data from our field surveys, the TTE and SBA models overestimated dhole population size beyond ecologically plausible limits, but the STE model produced reliable estimates for both the species. Our findings suggest that it is difficult to estimate population sizes of unmarked species when model assumptions are not fully met and data are sparse, which are commonplace for most ecological surveys in the tropics. Based on our assessment, we propose that practitioners who have access to photo-encounter data on dholes across Asia test old and new analytical approaches to increase the overall knowledge-base on the species, and contribute towards conservation monitoring of this endangered carnivore.

Keywords: Camera trapping; Canids; Conservation monitoring; Model evaluation; Site-based abundance; Space-to-event; Time-to-event; Unmarked species.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Canidae*
  • Carnivora*
  • Ecosystem
  • Panthera*
  • Population Density

Grants and funding

The field study in Radhanagari Wildlife Sanctuary was funded and permitted by the Maharashtra Forest Department, Govt. of India. Girish A Punjabi was supported by a grant from Vinati Organics Limited (VOL) to Wildlife Conservation Trust during the writing of this manuscript. Linnea Worsøe Havmøller received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 801199. Rasmus Worsøe Havmøller was supported by research grant 36069 from VILLUM FONDEN. Arjun Srivathsa was supported by the Wildlife Conservation Network. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.