Demography of an Afrotropical passerine in a highly fragmented landscape

Abstract

AbstractDemographic attributes of discrete subpopulations of animals and plants that constitute a larger (meta)population network may affect the strength and direction of local population responses to habitat loss or degradation. To address this question in an Afrotropical context, we studied survival rates, population densities, sex ratios and age distributions in seven white‐starred robin Pogonocichla stellata populations inhabiting differently sized forest remnants in a highly fragmented Kenyan landscape. Sex ratios were strongly male biased, especially during the non‐breeding season, but the level of bias did not differ between age groups nor fragment sizes. Juvenile to adult ratios were smallest in the medium‐sized fragment, but did not differ between the largest and smallest fragments. Low population density combined with a skewed sex ratio in the medium‐sized fragment pointed towards a local scarcity of females, which was supported by the presence of unmated territorial males. Based on capture–recapture analysis, all populations were considered stable on average. When combining demographic patterns with those emerging from a recent population genetic study and removal experiment, our results support the notion that small populations inhabiting tiny habitat remnants may play an important role in augmenting the long‐term survival of spatially structured populations.