Competition for resources mediated by intrinsic social dominance in sympatric finches

Abstract

Gouldian Erythrura gouldiae and Long-tailed Finches Poephila acuticauda are morphologically and ecologically similar sympatric species, for which social dominance relationships are likely to determine access to critical limiting resources. Building on previous research showing that Long-tailed Finches dominate competition for nest-sites, I staged dyadic contests for food between the two species in captivity in order to test social dominance dynamics under controlled conditions. Long-tailed Finches were likely to dominate interactions with Gouldian Finches and expressed higher levels of aggression while competing for access to food. These results suggest a stable dominance relationship between the two species which could be affecting Gouldian Finches' access to food resources in the wild, potentially constraining their ability to recover from recent population declines.