Giraffe numbers have decreased around 40% over the last thirty years, mainly because of anthropogenic causes, primarily poaching and habitat destruction. Diseases, including giraffe skin disease (GSD), however, also play a role in their decreasing numbers so are of concern to conservationists.
The first signals of GSD are small nodules with raised hair that develop into scabs. These scabs become dry and scaly patches and pruritus increases. GSD is widespread in Tanzania and it is hypothesized that, in severe cases, it might could increase the susceptibility of affected animals to be predated by lions because it affects their movement.
Photogrammetry is the quantification of photographic images and is an important tool in wildlife conservation. It is used mainly to measure the morphological characteristics of particular species and to identify individuals in a population.
This study is the first quantification of the severity of a dermatological pathology using photogrammetry of camera trap images. Long-term camera trap systems were installed in the Ruaha and Serengeti National parks to evaluate GSD.
385 images were suitable for photogrammetric analysis. Lesions were classified as mild (the most commonly seen), moderate or severe and the authors found more injuries in the front legs than in the hind limbs. A possible theory is that GSD is caused by filarial worms, mostly transmitted by insects, that are more efficiently deviated by giraffes’ tails.
Further studies to understand this skin disease epidemiology are necessary but it is suggested that photogrammetry, in combination with animal observation, can be a helpful non-invasive instrument to determine the consequences of skin problems on wildlife ecology.
Muneza A. et al. Quantifying the severity of giraffe skin disease via photogrammetry analysis of camera trap data. Journal of Wildlife Diseases, 55(4), 2019, pp. 770–781. DOI: 10.7589/2018-06-149
