Satellites, the all-seeing eyes in the sky: counting elephant seals from space

Clive R. McMahon, Hamish Howe, John Van Den Hoff, Rachael Alderman, Henk Brolsma, Mark A. Hindell

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Regular censuses are fundamental for the management of animal populations but, are logistically challenging for species living in remote regions. The advent of readily accessible, high resolution satellite images of earth mean that it is possible to resolve relatively small (0.6 m) objects, sufficient to discern large animals. To illustrate how these advances can be used to count animals in remote regions, individual elephant seals (Mirounga leonina) were counted using satellite imagery. We used an image taken on 10/10/2011 to count elephant seals (n = 1790±306 (95%CL)) on the isthmus of Macquarie Island, an estimate which overlapped with concurrent ground counts (n = 1991). The number of individuals per harem estimated using the two approaches were highly correlated, with a slope close to one and the estimated intercept also encompassing zero. This proof of concept opens the way for satellites to be used as a standard censusing technique for inaccessible and cryptically coloured species. Quantifying the population trends of higher order predators provides an especially informative and tractable indicator of ecosystem health.

Original languageEnglish
Article numbere92613
Pages (from-to)1-5
Number of pages5
JournalPLoS ONE
Issue number3
Publication statusPublished - 20 Mar 2014
Externally publishedYes

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