Tree-cavity nesting in buff-winged cinclodes (cinclodes fuscus) populations from northwestern argentine patagonia

Abstract

Cinclodes ovenbirds (Furnariidae) inhabit open habitats of South America, usually near water. The Buffwinged Cinclodes (C. fuscus) was recently recognized as a separate species, and data on its natural history are scarce. This species breeds in Patagonia and winters further north in Argentina and adjacent countries, although some populations in Chile breed in the Andes and winter on the Pacific coast. The few nests that have been described were placed in holes on cliffs, bridges, and road cuts in open Patagonian landscapes. Based on these data, the species is considered a typical representative of the genus (i.e., open habitat, ground-nesting ovenbird), and potential associations with forests have not been documented. Here I report on the breeding habits of C. fuscus in native forests of northwestern Argentine Patagonia, where these birds are regular summer residents. On the course of a long-term (1998-2016) research on the cavity-nesting birds of north Patagonian forests, I found 51 nests in 26 nesting cavities located in large lenga (Nothofagus pumilo) trees. Most nesting cavities were reutilized in different years. No nests were found in other substrates. This is the first time that consistent tree hole-nesting is documented for any species of Cinclodes. Future studies should determine whether differences in nesting behavior (ground nesting vs. tree-hole nesting) are explained by behavioral plasticity or represent patterns of genetic differentiation between forest and steppe C. fuscus populations.