Search

The Alder (Empidonax alnorum) and Willow (E. trailli) flycatchers are cryptic species, and their distribution outside the breeding season is poorly known, owing mostly to identification difficulties. Our new records suggest that large numbers of Alder Flycatchers overwinter in rivers crossing the Chaco region and in the foothill forests of the Yungas of Argentina, significantly increasing their southern wintering range. Records in northern Argentina span 3 November to 23 March. Key habitat for overwintering Alder Flycatchers in Argentina included stands of palo bobo (Tessaria integrifolia) along the Rio Bermejo and tributaries, either in association with sparse shrubs of chilca (Baccharis salicifolia) or more rarely with canebrake (Gynerium sagittatum). Other habitats used were old shrubby ‘madrejones' with Tessaria scrub and sacha cafe (Sesbania virgata), very dense Baccharis salicifolia scrub next to flowing creeks in foothill Yungas and dry Chaco, and riparian forests dominated by palo flojo (...