Reproduction and persistence of Vancouver Island marmots (Marmota vancouverensis) in natural and logged habitats

Abstract

I tagged and monitored Vancouver Island marmots (Marmota vancouverensis) to investigate demographic trends among colonies inhabiting natural subalpine meadows and recently logged habitats. Marmota vancouverensis exhibits low reproductive rates, with litter sizes of 2–5 ([Formula: see text], SD = 0.83, n = 36). Females are capable of breeding at age 3, but most animals did not breed until age 4 ([Formula: see text] years, SD = 0.82 years, n = 13), and displayed a nonreproductive interval of at least 1 year between litters ([Formula: see text] years, SD = 0.76 years, n = 6). Persistence of marmots was higher at natural sites than in logged areas (65 versus 48%). Maximum female age was 9 years in natural habitats and 5 years in clearcuts. No adult female inhabiting a clearcut (n = 14) produced more than a single litter, while 5 of 14 females in natural habitats produced 11 litters. The net reproductive value of colonies in clearcut habitats was less than half that of natural colonies (0.25 versus 0.72). Recently logged habitats may act as a demographic "sink" by consuming more dispersers than they produce, and therefore impede the recolonization of distant natural habitats.