Are mist-nets suitable for rapid habitat evaluations in the tropics? Results from a study in Guinea-Bissau.

There is an increasing need for rapid habitat evaluations, in the tropics, for conservation purposes. Biodiversity is often assessed by studying relat ively well known groups, such as birds. But even birds can be difficult to watch and identify in tropical habitats. Mist-netting is relatively free of observer bias, and allows sampling effort to be standardised. We sampled b irds by mist-netting in seven wooded habitats, covering a wide range of lev els of anthropogenic disturbance, in the Cufada region, Guinea Bissau. Capt ure rates, species diversity (as estimated by rarefaction) and originality of the bird communities appeared to be higher in disturbed habitats. Primar y forest had the lowest capture rate and the lowest diversity index. Origin ality was also very low in primary forest. We discuss several possible caus es for these patterns and argue that surveys based exclusively on mist-nett ing can be severely misleading, when comparing bird communities in differen t habitats.