Winter songs reveal geographic origin of three migratory seedeaters (Sporophila spp.) in southern neotropical grasslands

Abstract

The winter distribution of neotropical seedeaters (Sporophila spp.) known as capuchinos is poorly known. There are difficulties to understanding their migration patterns: fieldwork is lacking in their wintering areas, their ‘eclipse’ plumages often make it difficult to identify species, different species share habitats during winter, and there is little or no genetic differentiation of several forms. Vocalizations display a geographic signature (i.e., diagnostic acoustic features that are found in a limited area during the breeding period) and can be useful as indicators of a specific geographic origin of a wintering bird. I present data that: (1) demonstrates that non-breeding male Dark-throated Seedeater (S. ruficollis), Rufous-rumped Seedeater (S. hypochroma), and Tawny-bellied Seedeater (S. hypoxantha) in wintering areas can be assigned to a particular distant breeding population based on vocalizations; (2) evaluate the potential contribution of vocal variation in other capuchinos to understand their migratory movements; and (3) use vocalizations to unravel migration patterns of capuchinos. Non-breeding males of S. ruficollis from the Entre Rios regiolect were recorded in Cerrado habitat close to Vila Bela da Santı´ssima Trindade, Brazil and in the Beni savannas close to Trinidad, Bolivia, S. hypochroma from the Corrientes regiolect was recorded close to Vila Bela da Santı´ssima Trindade, and S. hypoxantha from the Entre Rı´os regiolect was recorded close to Trinidad. Linking breeding and non-breeding areas through song-types is important to understand the evolutionary ecology and to promote conservation of these tiny long-distance flyers.