Using Morphometrics to Estimate Age of Northern Idaho Ground Squirrels (Urocitellus brunneus)
Faculty Mentor Information
Courtney Conway Amanda Goldberg
Abstract
Estimating individual age plays a crucial role in the conservation and management of threatened and endangered species. Age specific vital rates can aid in modeling population trends, viability, and understanding potential threats to a species. Most accurate methods for estimating age cannot be obtained from live individuals, making these methods unsuitable for listed species. For the northern Idaho ground squirrel (Urocitellus brunneus), a threatened species endemic to Idaho, there are no current methods to discriminate age of live individuals ≥ 1 year of age. We analyzed 75 known age northern Idaho ground squirrels to determine if a suite of morphometrics obtained from live individuals could be used to estimate two or more age classes. Trapping was conducted at 15 northern Idaho ground squirrel sites on more than one occasion. We also evaluated variation of same age individuals among sites as well as the effects of observer bias on the accuracy of measurements used to estimate age. The ability to estimate age of live northern Idaho ground squirrels will improve population viability analyses and help determine whether management actions affect age-specific demography.
Using Morphometrics to Estimate Age of Northern Idaho Ground Squirrels (Urocitellus brunneus)
Estimating individual age plays a crucial role in the conservation and management of threatened and endangered species. Age specific vital rates can aid in modeling population trends, viability, and understanding potential threats to a species. Most accurate methods for estimating age cannot be obtained from live individuals, making these methods unsuitable for listed species. For the northern Idaho ground squirrel (Urocitellus brunneus), a threatened species endemic to Idaho, there are no current methods to discriminate age of live individuals ≥ 1 year of age. We analyzed 75 known age northern Idaho ground squirrels to determine if a suite of morphometrics obtained from live individuals could be used to estimate two or more age classes. Trapping was conducted at 15 northern Idaho ground squirrel sites on more than one occasion. We also evaluated variation of same age individuals among sites as well as the effects of observer bias on the accuracy of measurements used to estimate age. The ability to estimate age of live northern Idaho ground squirrels will improve population viability analyses and help determine whether management actions affect age-specific demography.