Factors affecting bird species richness in Selvagem and Canary Islands

Full article

Published:

Volume 49(2), December 2002. Pages 211-221.

Language:

Spanish

Original title:

Determinantes de la riqueza de especies de aves en las islas Selvagem y Canarias

Keywords:

Canary Islands, insular biogeography, landbirds, path analysis, Selvagem, species richness

Abstract:

Differences in the number of breeding landbird species among the Canary and Selvagem islands (Fig. 2) are analyzed according to physiographic-geological and vegetation variables (area, distance to mainland, maximum altitude and age of each island, average structural complexity of habitats in each island, and within-island habitat diversity; Table 1). A hypothesised model of relationships among variables was tested by means of a path analysis (Figures 1 and 3). Variation among islands in species richness supports the area per se and habitat diversity hypotheses. Within-island habitat diversity was closely related to the altitudinal range of the islands, but it was independent of area or geological age of islands. Distance to mainland negatively affected species richness. This is a striking result considering that the Canary and Selvagem islands are not a remote archipelago and that birds are a taxa with high disppersal abilities. Neither the average structural complexity of habitats in each island, nor the age of the islands had a significant contribution to the differences in species richness among islands.