Understanding animal distribution is a fundamental quest for ecologists. Behavioral decisions and the resulting movements of individual animals underlie animal distribution. One behavioral/movement tactic that many species employ is site fidelity – the tendency to return to previously visited sites. Site fidelity occurs at the individual level, but it is unknown how variation in individual fidelity influences animal distribution at the population level. It is clear that when individuals in a population have strong fidelity to a seasonal range, breeding site, or migration route, that the distribution of the population will also be consistent over time. However, it is unclear how low individual site fidelity influences the consistency of population distribution over time. One possibility is that long-term habitat variability may mediate this relationship as population distribution is closely tied with the distribution of habitat quality via individual habitat selection. Our objective is to develop a theoretical and empirical understanding of the relationship between individual fidelity and population distribution. We posit that under variable habitat quality, individual fidelity will determine changes in population distribution. Under consistent habitat quality, however, population distribution will remain consistent regardless of variation in individual fidelity.
Results/Conclusions
We will test these hypotheses by combining long-term, individual-based data from GPS collared, migratory ungulates in the Rocky Mountains with metrics of habitat variability derived from weather stations and remote sensing (e.g., variability in date of peak green-up, snow depth, and snow water equivalent). Preliminary results from a mule deer population in western Wyoming (n = 70 animal-years) over time suggests a positive relationship between individual fidelity to migration routes and consistency of population migration corridors over time (p-value = 0.01, pseudo r2 = 0.09). Preliminary results also suggest a very weak effect of variability in habitat quality on the consistency of population corridors. In the future, we will refine our metrics of habitat variability and include additional populations into the analyses. Conserving wildlife often hinges on mapping areas used by the majority of the population and our work will help determine how conservation investments may persist into the future. Further, our work informs how individual site fidelity scales-up and influences animal distribution.