Foraging behavior and diet of lined seedeaters (Sporophila lineola) in the breeding and wintering grounds

Migratory animals face seasonal variations in energetic and nutritional demands, especially between breeding and wintering grounds. In this study, we investigated the foraging behavior and diet of lined seedeaters ( Sporophila lineola ) between their breeding grounds in southeastern Brazil and wintering grounds in the Amazonia. The habitat used is a disturbed dry grassland in the breeding grounds and a natural wetland in the wintering grounds. Thus, we hypothesized that attack maneuvers would vary between habitats and that food items taken would also shift seasonally, with higher arthropod intake when breeding and higher seed intake when wintering. For that we recorded 135 and 147 foraging events in the breeding and wintering grounds, respectively, also analyzing the contents of 11 stomachs of museum specimens. Lined seedeaters were more likely to use Glean and Hang-up attack maneuvers in both grounds studied, but the proportion between them differed, likely reflecting differences in grass morphology between areas. Food category composition did not differ between grounds, with seeds being the dominant item in both areas. The diet included mainly seeds of Urochloa brizantha (an introduced African grass) in the breeding grounds, and seeds of Echinochloa polystachya and Paspalum repens (two native grasses from the Amazonia wetlands) in the wintering grounds. The stomach content analysis also confirmed the predominance of grass seeds in the diet of the species. We concluded that the lined seedeater is a generalist granivore capable of exploiting both native and invasive grasses. This flexibility may offer advantages over more specialized species in a changing world.