Spatio-temporal dynamics in syntopy are driven by variability in rangeland conditions

Sympatry is a common consequence of niche differentiation and can exist as broad sympatry (shared geographical region) or direct sympatry (i.e., syntopy [shared resource patch]). Syntopy may be highly dynamic, particularly in environments that experience stochastic events that increase variability in abiotic conditions and vegetation. We examined how estimates of syntopy varied across space and time in a rangeland system within the Southern Great Plains, USA over a three-year period (2013-2015). We modeled annual estimates of syntopy between three functionally similar (ground-foraging Galliformes) species (northern bobwhite [Colinus virginianus], scaled quail [Callipepla squamata], and lesser prairie-chicken [Tympanuchus pallidicinctus]. Niche similarity representing increased syntopy was greatest during years with increased drought conditions (2013-2014). Niche differentiation was greatest in 2015 in which rangelands experienced the greatest amount of precipitation. Syntopy estimates were driven by variability in vegetation cover estimates, representing changes in rangeland conditions related to abiotic conditions. Our results suggest that syntopy can be highly dynamic across space and time and can be driven by variability in abiotic conditions (i.e., precipitation). Furthermore, these results suggest that habitat is in a state of non-equilibrium. Finally, we highlight that climate refuges that promote demographic resiliency through intraspecific changes in resource use are fundamental drivers of spatio-temporal patterns in community dynamics, particularly across similar functional species.