PATTERNS OF NEST ORIENTATION IN THE GOLDEN BILLED SALTATOR (SALTATOR AURANTIIROSTRIS) IN CENTRAL ARGENTINA

In birds, nest location defines the microclimatic conditions for the development of eggs and nestlings. In general, direct solar radiation and wind are the main determinants of bird nest orientation patterns. In this study, we analyzed the orientation pattern of nests of the Golden-billed Saltator (Saltator aurantiirostris) in central Argentina. The nests were mainly oriented towards the north side of the substrate plant, with greater concealment from the south and west. Nest mean orientation in the species matches the conditions of higher solar radiation in the plant, although the vegetation concealment from above and west may compensate for the high exposure to solar radiation in the species. Nests were also placed in sites further from the foliage edge and were supported by more branches, variables that may be associated with reduced risk of nest predation. Overall our results show that the selection of nesting sites in the Golden-billed Saltator may involve a number of decisions to maximize microclimatic conditions that may aid the thermoregulation of eggs and nestlings, while minimizing the risk of nest predation.