Ranging behaviour and habitat use by an Afrotropical songbird in a fragmented landscape

Habitat attrition may affect ranging patterns of individuals in natural populations, e.g. by engendering larger territory sizes as the preferred habitat decreases. Radio-telemetry was used to explore the ranging behaviour of the whitestarred robin Pogonocichla stellata in the highly fragmented Taita Hills landscape, south-east Kenya. Thirty-one males were radio-tracked in seven indigenous forest fragments differing in size and disturbance level. Although range size did not differ amongst patches, ranges overlapped more in the densely populated fragments. Using principal factor analysis, three principal factors corresponding to ‘openings’ (little foliage cover in all three strata), ‘proper forest’ (three-stratum forest) and ‘forest gaps’ (open upper canopy, dense understorey) were extracted. In all fragments, robins selected sparse to moderate foliage habitats, which best matched to the ‘proper forest’ factor, over open or very dense ones. Yet, the proportion of this preferred vegetation structure within home ranges differed across the forest fragments. Thus, lesser amounts of the selected habitat within the home ranges did not result in larger ranges. This could indicate high robin adaptability, surviving well with only nominal amounts of the preferred habitat within its home range. This is consistent with previous findings on this species based on fluctuating asymmetry and genetics.