Colony site choice of blue‐tailed bee‐eaters: influences of soil, vegetation, and water quality

Abstract

All bee‐eaters (Family Meropidae) are cavity nesters, excavating terrestrial burrows in sites ranging from flat ground, to small mounds of soil, steep earthen banks seen in road clearings, eroded cliff faces, and river gorges. However, very little is known concerning the environmental factors that influence nest site selection in bee‐eaters. We addressed abiotic and biotic issues associated with colony site choice in blue‐tailed bee‐eaters (Merops philippinus) nesting on Kinmen Island, off mainland China, from 2000 to 2002. About 89% of the colonies were located on slopes with soils of sandy loam and the other 11% on sandy clay loam. No colony was found on clay loam, which covered 20% of the island. The sandy loam and sandy clay loam had lower soil pressure, density and moisture, which, presumably, were easier for bee‐eaters to excavate and provided better drainage and ventilation for nest cavities. Bee‐eaters avoided placing nest cavities in areas with dense vegetation and abandoned colony sites when they became overgrown. Vegetation would impede excavation and decrease the detectability of predators. Bee‐eaters may prefer colony sites near water bodies showing water chemistries indicative of more biological productivity, especially in relation to the diversity and abundance of their major prey, dragonflies.