Disparate functionality in shrub communities as assessed through space use of the chestnut-bellied scaled quail

Human disturbance on vegetation communities can result in alternative stable states in ecosystems, which often present animals with novel environments and may lead to evolutionary mismatches. The chestnut-bellied scaled quail (Callipepla squamata var. castanogastris; hereafter: “scaled quail”) is a shrubland-obligate subspecies of scaled quail native to South Texas, USA that has faced population declines in recent decades, despite increasing shrub cover across their distribution. These shrublands often arise after brush management and are structurally distinct from the Tamaulipan thornscrub it replaced, which may represent an alternative stable state changing functional responses of this species. Examine the movement and selection of scaled quail in response to combinations of vegetation community and vegetation structure (representing alternative stable states) across within-diel (4 hr) and across-diel (12 hr) cycle temporal grains. From 2022 to 2023, we fit individuals with GPS transmitters and subsequently used step selection functions (SSF) to estimate responses to changes in vegetation community states at two study sites in South Texas (one declining [peripheral] and one stable [core] population). Birds avoided disturbed shrubland communities (mesquite savanna and woodland), and avoidance became stronger in the presence of high herbaceous biomass, suggesting that a combination of vegetation community and structure associated with disturbed shrublands affects selection. This avoidance was strongest at the 12 h temporal grain and was largely driven by the presence of high herbaceous biomass. Structural differences between Tamaulipan thornscrub and disturbed shrublands may impact functional habitat connectivity for scaled quail, even if shrublands are still present.