A computer-assisted system for photographic mark-recapture analysis

Bolger, D. T., Morrison, T. A., Vance, B., Lee, D. and Farid, H. (2012) A computer-assisted system for photographic mark-recapture analysis. Methods in Ecology and Evolution, 3(5), pp. 813-822. (doi:10.1111/j.2041-210X.2012.00212.x)

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Abstract

Summary: 1. Photographic mark–recapture is a cost‐effective, non‐invasive way to study populations. However, to efficiently apply photographic mark–recapture to large populations, computer software is needed for image manipulation and pattern matching. 2. We created an open‐source application for the storage, pattern extraction and pattern matching of digital images for the purposes of mark–recapture analysis. The resulting software package is a stand‐alone, multiplatform application implemented in Java. Our program employs the Scale Invariant Feature Transform (SIFT) operator that extracts distinctive features invariant to image scale and rotation. 3. We applied this system to a population of Masai giraffe (Giraffa camelopardalis tippelskirchi) in the Tarangire Ecosystem in northern Tanzania. Over 1200 images were acquired in the field during three primary sampling periods between September 2008 and December 2009. The pattern information in these images was extracted and matched resulting in capture histories for over 600 unique individuals. 4. Estimated error rates of the matching system were low based on a subset of test images that were independently matched by eye. 5. Encounter histories were subsequently analysed with open population models to estimate apparent survival rates and population size. 6. This new open‐access tool allowed photographic mark–recapture to be applied successfully to this relatively large population.

Item Type:Articles
Additional Information:This work was supported by the National Science Foundation grant 0754773to DTB and HF. Support is also acknowledged from the Neukom Institute forComputational Science at Dartmouth College, Marion and Jasper WhitingFoundation, the Nelson A. Rockefeller Centre at Dartmouth College. Wethank the Commission for Science and Technology and the Tanzania WildlifeResearch Institute for permission to conduct research in Tanzania, and theTanzania National Parks for permission to work in Tarangire National Parkand Robert Mollel for his assistance in the field.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Morrison, Dr Thomas
Authors: Bolger, D. T., Morrison, T. A., Vance, B., Lee, D., and Farid, H.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Methods in Ecology and Evolution
Publisher:Wiley for the British Ecological Society
ISSN:2041-210X
ISSN (Online):2041-210X

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