Habitat use and coexistence in two closely related species of Herpsilochmus (Aves: Thamnophilidae)

Ecological theory predicts that species with similar niches cannot coexist on a limited resource. To allow for coexistence species would differentiate in resource use. Species that have similar ecology could coexist providing that they have different patterns of habitat use and associations with different environmental variables. In addition, similarity among species could be influenced by habitat structure and resource availability. Here, we build models of habitat use in high resolution (50 × 50 m), for two closely related species of birds in Northeast Brazil (Herpsilochmus sellowi–Caatinga Antwren and Herpsilochmus pectoralis–Pectoral Antwren). We use ecological niche factor analysis to detail the relationship between species and their habitat requirements. Our models brought new information about habitat use and how species respond to environmental variability. Habitat heterogeneity promotes the existence of distinct habitats that can be differently occupied by the species. Our analysis revealed that the two species have different strategies. H. pectoralis was very selective (specialist), while H. sellowi was habitat generalist. The use of different habitats can reduce the effect of interspecific competition to levels that allow coexistence. Our results suggest that habitat segregation as proposed by classical niche theory can explain coexistence of these two species in our study site