spatial and temporal variation in biotic and abiotic conditions in any foraging environment prompts individuals to modify their strategies of space use and behavioral responses such as going from solitary to social foraging, as it occurs with flocking in forest birds. while asymmetric intraspecific competition determines differential habitat selection, the occurrence and foraging activity of others, conspecifics or even congeners, can also inform on fitness prospects and provide floaters or flock attendants additional foraging opportunities when searching for alternative habitats. whether interspecific interactions between congeneric species modulate habitat use in a species that occurs at low densities during the non-breeding period remains less known. here, i study two neotropical migratory bird species that join flocks: the endangered golden-cheeked warbler (gcwa; setophaga chrysoparia) and the townsend’s warbler (towa; s. townsendi). the main objective was to describe social mechanisms underlying habitat preference in the former species by looking at foraging strategies and interactions with its congener that might influence its habitat selection. a secondary goal was to provide knowledge on the nonbreeding ecology of gcwa toward conservation recommendations. [...]