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10 March 2016 Precision, accuracy, and costs of survey methods for giraffe Giraffa Camelopardalis
Derek E. Lee, Monica L. Bond
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Giraffes Giraffa camelopardalis are megafaunal browsers and keystone species in African savanna ecosystems. Range-wide population declines are suspected, but robust data are lacking. Tanzania holds the largest population of giraffe of any range state, and aerial surveys constitute most of Tanzania's giraffe population monitoring data, but their accuracy has not yet been assessed. An IUCN status assessment for giraffe is currently underway, and calibrating aerial surveys with ground-based surveys can quantify accuracy of the aerial surveys to ensure more reliable estimates of populations nationwide. We estimated giraffe density and abundance in the Tarangire Ecosystem in northern Tanzania using 2 ground survey methods, distance sampling and capture-mark-recapture, and compared our ground-based estimates with those from the most recent aerial survey in 4 sites. We found aerial survey estimates were biased low, while ground-based surveys were more precise and cost less. We computed correction factors to improve the accuracy of aerial surveys and suggested ways to further improve aerial survey methods.

© 2016 American Society of Mammalogists,
Derek E. Lee and Monica L. Bond "Precision, accuracy, and costs of survey methods for giraffe Giraffa Camelopardalis," Journal of Mammalogy 97(3), 940-948, (10 March 2016).
Received: 1 December 2015; Accepted: 29 January 2016; Published: 10 March 2016

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