Nest Orientation in Closed Nests of Passeriformes across a Latitudinal Gradient in the Southern Neotropic

GARCIA, CECILIA G.; SCHAAF, ALEJANDRO A.; GREENEY, HAROLD F.

ACTA ORNITHOLOGICA

MUSEUM & INST ZOOLOGY

Año: 2020 vol. 54 p. 255 - 262

0001-6454

Abstract. Birds are expected to orient their nests non-randomly in order to avoid extreme thermal conditions that areknown to affect their reproductive success. Considering the hypotheses that yearly mean temperature influencesentrance orientation in birds, nests at higher latitudes are expected to face the equator in order to take advantage ofwarmer temperatures. Here we explore the relationship between latitude and nest entrance orientation in closed nestsof Passeriformes in the southern Neotropics (Furnariidae, Rhinocryptidae, Troglodytidae, Tyrannidae), using both publishedand original data. We found a positive and significant correlation between mean entrance orientation and latitude,and report significantly non-random nest orientation at 62% of the locations with available samples. Overall, thereis a trend for nests at lower latitudes to have north-northeasterly orientations, and for nests at higher latitudes to be orientednorthwest. The reasons for the observed trends remain unclear, but likely involve the availability and intensityof solar radiation and its effect upon the nest microclimate.