Habitat selection by the Pale-breasted Spinetail (Synallaxis albescens) at multiple spatial scales in the central Monte Desert, Argentina

Habitat selection by birds is the result of hierarchical decisions that may be based on different cues at different spatial scales. However, studies rarely assess patterns of selection at multiple scales simultaneously in order to understand the processes leading to the observed selection patterns. In the central Monte Desert, at the habitat scale, the density of Pale-breasted Spinetails (Synallaxis albescens) during the breeding season is higher in mesquite (Prosopis flexuosa) open woodlands than in creosote (Larrea cuneifolia) shrublands. Causes of this pattern may be revealed by exploring how Pale-breasted Spinetails use space at different scales. At the microhabitat scale, birds selected the highest mesquite trees and avoided creosotes for territorial displays. However, they did not establish territories in patches where mesquite trees were taller than expected. Moreover, at the mesohabitat scale, the cover of mesquite trees within territories was greater than expected only in the plot with a lower cover of mesquite trees. Therefore, the pattern of vegetation selection at the habitat scale matched that at the microhabitat scale, but not completely at the mesohabitat scale. Our study provides insight about the mechanisms driving patterns of habitat selection by Pale-breasted Spinetails in the central Monte Desert. It also highlights the significance of considering vegetation structure and composition at multiple spatial scales when evaluating how birds select where to establish their territories.