First Record of the Southern Red-Backed Vole, Clethrionomys gapperi, in Newfoundland: Implications for the Endangered Newfoundland Marten, Martes americana atrata

We report on the first capture of the Southern Red-backed Vole (Clethrionomys gapperi), the eleventh non-native terrestrial mammal established on the island of Newfoundland over the last 150 years. Red-backed Voles may have been accidentally introduced by unknown sources in pulpwood imports or may have been deliberately introduced in an attempt to augment the depauperate small mammal fauna as a vigilante recovery effort for the endangered Newfoundland Marten (Martes americana atrata). We anticipate significant utilization of the Red-backed Vole as prey by both Newfoundland Marten and Red Fox (Vulpes vulpes) with associated demographic responses within and between these species. Red-backed Voles will likely change habitat utilization patterns for the endemic subspecies of Meadow Vole, Microtus pennsylvanicus terraenovae.

Nitrogen- and carbon-isotope fractionation between mothers and offspring in red-backed voles (Clethrionomys gapperi)

Small mammals are income breeders, but the degree to which females draw from maternal reserves and partition nutrients to the mammary glands in the wild is not known. This study examined stable-nitrogen and stable-carbon isotopes in red-backed vole, Clethrionomys gapperi (Vigors, 1830), hair to determine mother–offspring trophic relationships and to consider the extent to which voles rely on maternal reserves during lactation. Both dependent and independent young showed isotopic enrichment in 15N and depletion of 13C in their hair relative to mothers. We suggest that growing offspring, both dependent and independent, may catabolize body reserves to support both growth and moult. We propose that the nitrogen- and carbon-isotope compositions of hair may be more useful indicators of metabolic rate than mother–offspring trophic relationships in small mammals.

Effects of extra food on nestling growth and survival in red-backed voles (Clethrionomys gapperi)

Nestling mortality is typically high among small mammals, with food often considered an important limiting factor because of the increased energetic costs females incur during lactation. We provided female red-backed voles, Clethrionomys gapperi (Vigors, 1830), with sunflower seeds during lactation to test the hypothesis that food supply influences nestling growth and survival. Food supplementation did not increase nestling survival, but newly emerged young from fed mothers were significantly heavier than those from unfed mothers. High mortality/dispersal of postemergent young, particularly females, was associated with high densities of breeding females. We suggest that any survival advantage incurred from higher nestling growth rates may be mitigated by density-dependent mortality/ dispersal postemergence.