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This paper assessed the reliability of this simple, freely available software package …


Biology Articles » Conservation Biology » Spot the match – wildlife photo-identification using information theory

Abstract
- Spot the match – wildlife photo-identification using information theory

Spot the match – wildlife photo-identification using information theory
 
Conrad W Speed,1,2 Mark G Meekan,2 and Corey JA Bradshaw 1
 
1School for Environmental Research, Institute of Advanced Studies, Charles Darwin University, Darwin, Northern Territory 0909, Australia
2Australian Institute of Marine Science, P.O. Box 40197, Casuarina MC, Northern Territory 0811, Australia
 
Conrad W Speed: conrad.speed@students.cdu.edu.au ; Mark G Meekan: m.meekan@aims.gov.au ; Corey JA Bradshaw: corey.bradshaw@cdu.edu.au

 

Background
 
Effective approaches for the management and conservation of wildlife populations require a sound knowledge of population demographics, and this is often only possible through mark-recapture studies. We applied an automated spot-recognition program (I3S) for matching natural markings of wildlife that is based on a novel information-theoretic approach to incorporate matching uncertainty. Using a photo-identification database of whale sharks (Rhincodon typus) as an example case, the information criterion (IC) algorithm we developed resulted in a parsimonious ranking of potential matches of individuals in an image library. Automated matches were compared to manual-matching results to test the performance of the software and algorithm.

Results

Validation of matched and non-matched images provided a threshold IC weight (approximately 0.2) below which match certainty was not assured. Most images tested were assigned correctly; however, scores for the by-eye comparison were lower than expected, possibly due to the low sample size. The effect of increasing horizontal angle of sharks in images reduced matching likelihood considerably. There was a negative linear relationship between the number of matching spot pairs and matching score, but this relationship disappeared when using the IC algorithm.

Conclusion

The software and use of easily applied information-theoretic scores of match parsimony provide a reliable and freely available method for individual identification of wildlife, with wide applications and the potential to improve mark-recapture studies without resorting to invasive marking techniques.
 
Front Zool. 2007; 4: 2. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0).

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