Comparison between telemetry and spot-mapping to determine space use of the Kenyan endemic Hinde's babbler

Abstract

Abstract:Different methods to measure species behaviour and space use may produce diverging results, and provide advantages and shortcomings. Data from spot-mapping of animals might be affected from restricted detectability of individuals in dense vegetation, while radio-tracking provides a less biased (or even unbiased) measure of space use. Here we compare results from spot-mapping and telemetry of four family groups (i.e. five individuals belonging to these four family groups), respectively of the Kenyan endemic cooperative-breeding bird Hinde's babbler, Turdoides hindei. Data from spot-mapping showed that the space use of T. hindei is mostly restricted to riparian vegetation. Home-range sizes calculated from telemetry were five times larger if compared with data obtained from spot-mapping. Telemetry data showed that T. hindei also moves across agricultural land, and mean and maximum displacements are larger if compared with data obtained from spot-mapping. Several reasons might lead to these differences: (1) Telemetry data also consider rare long-distance excursions, while (2) observers of spot-mapping might fail to observe long-distance movements and thus underestimate home-range sizes as well as displacement distances; (3) results from telemetry might become blurred from measurement error during the triangulation of fixes. Our study confirms that both methods provide advantages, but also shortcomings, which need to be considered when selecting a method to elaborate a research question.