Southeastern Orientation of Entrances of Yellow-Tufted Woodpecker Melanerpes cruentatus Cavities on the Equator

Abstract

Woodpeckers play important ecological roles as excavators of tree cavities, many of which are subsequently used by other vertebrate species. Tree cavities may serve as either roosting or nesting sites, providing protection from external climatic elements and predation. Cavity entrances are hypothesized to be excavated in directions that allow for maintenance of microclimatic variables inside the cavity, or are alternatively linked to wood hardness of cavity-bearing trees, and are for those reasons often non-randomly oriented. It has been suggested that the mean direction of these cavity entrances vary across latitudes, from south-facing entrances at high latitudes to entrances facing east and west closer to the tropics. I show non-random distribution of the orientation of cavities excavated by at least one species of woodpecker i.e. Yellow-tufted Woodpecker Melanerpes cruentatus near Tena, Ecuador, and that entrances face predominantly towards the southeast. This study is a first step to gather ecological information on tree-cavity-nesting communities in this region, with the factors driving non-random orientation to be tested in future studies.