Effects of sun exposure and vegetation cover on Woodpecker nest orientation in subtropical forests of South America

Variations in the orientation behavior of Woodpecker nests can be due to environmental factors such as latitude as well as local climate conditions. In this study, the orientations of dot-fronted Woodpecker nesting cavities (Veniliornis frontalis, Picidae) were examined at a subtropical site in Northwestern Argentina. It was evaluated whether solar radiation influences the mean orientation of cavities well covered by vegetation and cavities with less or non-external vegetal protection. Results obtained in this work provide that both covered and uncovered nests orient in a defined way towards the North and the Northwest, respectively, finding mean differences between both types of vegetation cover. These results indicate that, being exposed to the North (protected cavities) they get more solar radiation during the day to reduce the humidity of cavities' microhabitat, due to the intense rainfall; and Northwest (unprotected cavities); to increase the temperature within the cavity due to the low night temperatures and humid climate. This study highlights the importance of studying the vegetation over the nests (protection) together with the local climatic conditions, given that they are important determinants for bird nest orientation.