Tree Squirrel Introduction: A Theoretical Approach with Population Viability Analysis
Open Access
- 1 October 2007
- journal article
- Published by Oxford University Press (OUP) in Journal of Mammalogy
- Vol. 88 (5), 1271-1279
- https://doi.org/10.1644/06-mamm-a-303.1
Abstract
Reintroduction efforts require knowledge of how many animals are needed for successful establishment. Population viability analysis can be used to predict trajectories of introduced populations and tree squirrels provide an ideal model system to investigate this challenge. Conservation action is needed because more than 80% of species of tree squirrels are of precarious conservation status in some portion of their range. We combined data from closely related species of tree squirrels and used VORTEX to determine how many squirrels are needed to successfully establish populations of 6 species (Sciurus aberti, S. carolinensis, S. niger, S. granatensis, S. vulgaris, and Tamiasciurus hudsonicus). We ran multiple simulations to account for between-patch differences in breeding success (resource availability) and variation between years in different habitats. In the best-case scenarios, populations could be successfully established with fewer than 35 individuals for all species and as few as 15 for a subset of species. Empirical evidence from introductions of tree squirrels supports our simulation results, with 93% of populations of greater than 10 squirrels surviving more than 50 years. With relatively few individuals needed for establishing new squirrel populations, reintroductions are feasible and useful as a buffer for imperiled species.Keywords
This publication has 55 references indexed in Scilit:
- Spread and attempted eradication of the grey squirrel (Sciurus carolinensis) in Italy, and consequences for the red squirrel (Sciurus vulgaris) in EurasiaBiological Conservation, 2003
- Does increased stochasticity speed up extinction?Journal of Mathematical Biology, 2001
- BREEDING DISPERSAL IN FEMALE NORTH AMERICAN RED SQUIRRELSEcology, 2000
- Population Viability Analysis of Captive and Released Bearded Vulture PopulationsConservation Biology, 1996
- Movements, Site Fidelity and Survival of Delmarva Fox Squirrels Following TranslocationThe American Midland Naturalist, 1994
- Does Food Availability affect Growth and Survival of Males and Females Differently in a Promiscuous Small Mammal, Tamiasciurus hudsonicus?Journal of Animal Ecology, 1993
- Documentation of the Transplanting of Abert's SquirrelsThe Southwestern Naturalist, 1988
- Reintroducing Red Squirrels into Regent's ParkMammal Review, 1986
- Turnover Rates in Insular Biogeography: Effect of Immigration on ExtinctionEcology, 1977
- The Vital Statistics of an Unexploited Gray Squirrel PopulationThe Journal of Wildlife Management, 1970