Quantifying the severity of giraffe skin disease via photogrammetry analysis of camera trap data

Arthur B. Muneza, Waldemar Ortiz-Calo, Craig Packer, Jeremy J. Cusack, Trevor Jones, Meredith S. Palmer, Alexandra Swanson, Margaret Kosmala, Amy J. Dickman, David W. Macdonald, Robert A. Montgomery

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Developing techniques to quantify the spread and severity of diseases afflicting wildlife populations is important for disease ecology, animal ecology, and conservation. Giraffes (Giraffa camelopardalis) are in the midst of a dramatic decline, but it is not known whether disease is playing an important role in the broad-scale population reductions. A skin disorder referred to as giraffe skin disease (GSD) was recorded in 1995 in one giraffe population in Uganda. Since then, GSD has been detected in 13 populations in seven African countries, but good descriptions of the severity of this disease are not available. We photogrammetrically analyzed camera trap images from both Ruaha and Serengeti National parks in Tanzania to quantify GSD severity. Giraffe skin disease afflicts the limbs of giraffes in Tanzania, and we quantified severity by measuring the vertical length of the GSD lesion in relation to the total leg length. Applying the Jenks natural breaks algorithm to the lesion proportions that we derived, we classified individual giraffes into disease categories (none, mild, moderate, and severe). Scaling up to the population level, we predicted the proportion of the Ruaha and Serengeti giraffe populations with mild, moderate, and severe GSD. This study serves to demonstrate that camera traps presented an informative platform for examinations of skin disease ecology.

Original languageEnglish (US)
Pages (from-to)770-781
Number of pages12
JournalJournal of wildlife diseases
Volume55
Issue number4
DOIs
StatePublished - Oct 2019

Bibliographical note

Funding Information:
Our thanks to the Leiden Conservation Foundation, Giraffe Conservation Foundation, the American Society of Mammologists, Roger Williams Zoo, and the US Fish and Wildlife Service African Elephant Fund for their generous support of this research. Thanks to Athumani Mndeme, Peter Mtyana, Leons Mlawila, and Josephine Smit (all of the Southern Tanzania Elephant Program) for help with camera-trapping and data management. We thank the UK Natural Environment Research Council for purchasing a number of the camera traps used in the study in Ruaha National Park (grant NE/J016527/1). The Serengeti National Park camera trap survey was supported by NSF grant DEB-1020479, the University of Minnesota Supercomputing Institute, the National Geographic Society, the Alfred P. Sloan Foundation, Explorer?s Club, the American Society of Mammalogists, the Minnesota Zoo, and private donations raised during crowdfunding campaigns. We thank the many volunteers who contributed Snapshot Serengeti classifications to determine images containing giraffes. We recognize the assistance provided by the Tanzania Commission for Science and Technology, Tanzania National Parks Authority, and Tanzania Wildlife Research Institute officials in making this research possible.

Funding Information:
Our thanks to the Leiden Conservation Foundation, Giraffe Conservation Foundation, the American Society of Mammologists, Roger Williams Zoo, and the US Fish and Wildlife Service African Elephant Fund for their generous support of this research. Thanks to Athumani Mndeme, Peter Mtyana, Leons Mlawila, and Josephine Smit (all of the Southern Tanzania Elephant Program) for help with camera-trapping and data management. We thank the UK Natural Environment Research Council for purchasing a number of the camera traps used in the study in Ruaha National Park (grant NE/J016527/1). The Serengeti National Park camera trap survey was supported by NSF grant DEB-1020479, the University of Minnesota Supercomputing Institute, the National Geographic Society, the Alfred P. Sloan Foundation, Explorer’s Club, the American Society of Mammalogists, the Minnesota Zoo, and private donations raised during crowdfunding campaigns. We thank the many volunteers who contributed Snapshot Serengeti classifications to determine images containing giraffes. We recognize the assistance provided by the Tanzania Commission for Science and Technology, Tanzania National Parks Authority, and Tanzania Wildlife Research Institute officials in making this research possible.

Keywords

  • Camera traps
  • Giraffe skin disease
  • Lesions
  • Photogrammetry
  • Ruaha
  • Serengeti
  • Tanzania

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