Measuring habitat suitability is important in conservation and in<br />wildlife management. Measuring the abundance or presence-absence of a<br />species in various habitats is not sufficient to measure habitat<br />suitability because these metrics can be poor predictors of population<br />success. Therefore, having some measure of population success is<br />essential in assessing habitat suitability, but estimating population<br />success is difficult. Identifying suitable proxies for population<br />success could thus be beneficial. We examined whether faecal<br />corticosterone metabolite (fCM) concentrations could be used as a proxy<br />for habitat suitability in common gartersnakes (Thamnophis sirtalis). We<br />conducted a validation study and confirmed that fCM concentrations<br />indeed reflect circulating corticosterone concentrations. We estimated<br />abundance, reproductive output and growth rate of gartersnakes in field<br />and in forest habitat and we also measured fCM concentrations of<br />gartersnakes from these same habitats. Common gartersnakes were more<br />abundant and had higher reproductive outputs and higher growth rates in<br />field habitat than in forest habitat, but fCM concentrations did not<br />differ between the same two habitats. Our results suggest either that<br />fCM concentrations are not a useful metric of habitat suitability in<br />common gartersnakes or that the difference in suitability between the<br />two habitats was too small to induce changes in fCM concentrations.<br />Incorporating fitness metrics in estimates of habitat suitability is<br />important, but these metrics of fitness have to be sensitive enough to<br />vary between habitats.
Halliday, W. D., Gilmour, K. M., & Blouin-Demers, G. (2015). Faecal corticosterone metabolite concentrations are not a good predictor of habitat suitability for common gartersnakes. Conservation Physiology, 3(1). https://doi.org/10.1093/conphys/cov047