Can post-capture photographic identification as a wildlife marking technique be undermined by observer error? A case study using King Cobras in northeast Thailand

PLoS One. 2020 Dec 9;15(12):e0242826. doi: 10.1371/journal.pone.0242826. eCollection 2020.

Abstract

Identifying individuals with natural markings is increasing in popularity to non-invasively support population studies. However, applying natural variation among individuals requires careful evaluation among target species, snakes for example have little validation of such methods. Here we introduce a mark-free identification method for King Cobras (Ophiophagus hannah) from the Sakaerat Biosphere Reserve, in northeast Thailand using both subcaudal scale pholidosis (scale arrangement and number) and unique ventral body markings to distinguish individuals. This project aims to evaluate the impact of observer error on individual identification. Observers of varying expertise, will distinguish between King Cobra individuals using identifying photographs from a previous study. We will ask randomly assigned observers to distinguish individuals via: 1) subcaudal pholidosis, 2) ventral body markings, and 3) combination of both measures. Using Bayesian logistic regression, we will assess the probability observers correctly distinguish individuals. Based on exploratory observations, we hypothesise that there will be a high probability of correct identifications using subcaudal pholidosis and ventral body markings. We aim to stimulate other studies implementing identification techniques for scrutinous assessment of such methods, in order to avoid subsequent errors during long-term population studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Behavior, Animal*
  • Observer Variation
  • Ophiophagus hannah* / classification
  • Photography*
  • Thailand

Grants and funding

We were supported by the National Science and Technological Development Agency of Thailand via P.S. and Wildlife Reserves Singapore via C.T.S. and M.D.J. The funders had and will not have a role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.