Broad scale patterns of conditions and resources can affect both the distributions of organisms and their population dynamics. However, discrete events such as extreme weather may also influence organisms individually and at the population level. Depending on the scale of investigation, these discrete events can often go undetected as they are averaged across seasons and years. Thermal stress in particular has been identified as a potential mechanism in determining space use and survival of organisms at fine temporal and spatial scales. To better understand the effect of discrete temperature events on a member of Galliformes (Colinus virginianus; northern bobwhite), we evaluated space use across an ambient temperature gradient (ranging from -20 °C to 38 °C) through a Maxent algorithm using telemetry locations from 895 northern bobwhite.
Results/Conclusions
Estimated useable space ranged from 18.6% to 57.1% of the landscape depending on ambient temperature. Specifically, we found that during both high and low temperatures (<-15 °C and >35 °C, respectively) much of the landscape was estimated to be unused (81.4% and 75.4% respectively), including areas of the landscape that were selected for during more moderate temperatures. We also found dissimilarity in northern bobwhite space use during times of thermal extremes compared to each other and to more moderate conditions (range overlap = 0.38), implying habitat under one set of environmental conditions may not be habitat under varying environmental conditions. Additionally, using Andersen-Gill proportional hazard models, we found northern bobwhite survival was most influenced by weekly minimum ambient temperatures. Therefore, both space use and survival of northern bobwhite were constrained during temperature extremes. These results demonstrate that ecological constraints can occur because of environmental pinch points at fine temporal scales. Failure to account for discrete environmental conditions and how they affect organisms can lead to an incomplete understanding of habitat requirements and how management may influence populations.