Microhabitat selection by the Oscura Mountains Colorado Chipmunk (Neotamias quadrivittatus oscuraensis): an old-growth pinyon–juniper woodland specialist

Abstract

Habitat specialists have been largely overlooked in old-growth pinyon–juniper woodlands, despite specialists exhibiting heightened sensitivity to anthropogenic habitat loss. Furthermore, small mammal relationships within pinyon–juniper woodlands have most commonly been investigated via species abundance or habitat use, rather than habitat selection, thereby providing limited management metrics. We used the Oscura Mountains Colorado Chipmunk (Neotamias quadrivittatus oscuraensis) as a model organism to evaluate whether old-growth conditions drive resource selection by small mammals associated with pinyon–juniper woodlands. The goal of our study was to determine resources important to the chipmunk to inform management decisions. We evaluated microhabitat selection by testing a priori predictions based on natural history characteristics of the chipmunk and the woodlands. We grouped predictions into habitat characteristics affiliated with or not affiliated with old growth. We tested predictions under a multistage modeling framework using generalized linear mixed models with a binomial response variable of use versus availability. Probability of selection by chipmunks increased with increasing mean juniper diameter and increasing variation of pinyon diameter and decreased with increased distance to rocky escape terrain and increased mean percent grass cover. Our findings support the classification of the Oscura Mountains Colorado chipmunk as an old-growth pinyon–juniper specialist, as the chipmunk displayed disproportionate preference for old-growth microhabitat conditions. We recommend management policies that conserve old-growth multiage stands of pinyons and junipers. Old-growth conditions near outcroppings, escarpments, and large boulders are of particular conservation concern. Further, thinning resulting in increased grass cover may be detrimental to this old-growth pinyon–juniper specialist.