How Does Melanism Affect Survival Rate of Eastern Gray Squirrels (Sciurus carolinensis) in Schmeekle Reserve, Stevens Point, WI?

Abstract

Eastern gray squirrels (Sciurus carolinensis) are commonly found at higher densities in urban areas; however, vehicle collisions and other anthropogenic threats can cause mortality. Melanism in gray squirrels is caused by a genetic mutation and is thought to occur at higher rates in urban areas and more northern environments. Melanism has been shown to decrease survival rates in rural forest environments, possibly due to easier predation of melanistic squirrels, and has been shown to have no effect on survival in highly urbanized settings. We hypothesize that survival rates of melanistic gray squirrels will be lower than those from other gray squirrels. Students with the University of Wisconsin-Stevens Point chapter of The Wildlife Society have been trapping gray squirrels in Schmeekle Reserve, a 113-hectare urban natural area, since 2020. Squirrels are trapped from February to mid-March of each year, and data including sex, age, and fur variant are recorded. Each trapping season, several melanistic individuals are captured. We will use Program MARK to analyze these data in a Cormack Jolly Seber framework to determine if melanism affects survival of gray squirrels in Schmeeckle Reserve. We aim to understand how urban adapted animals, such as the Eastern gray squirrel, evolve with their environment to help managers better understand the impact of urbanization on wildlife.