Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

2009

Thesis Director

Thomas Nelson

Thesis Committee Member

Jim Novak

Thesis Committee Member

Paul Switzer

Abstract

Two species of tree squirrels inhabit Charleston, IL; fox squirrels (Sciurus niger) and gray squirrels (Sciurus caro/inensis). Although these species are sympatric throughout much of the eastern U.S., urban settings are usually occupied by one or the other. In the few localities where they co-occur, little is known about how they partition habitat. Therefore, the objectives of my study were to determine: (1) the relative abundance of each species, (2) whether habitat use differs between species, (3) if habitat use shifts with season, time of day, domestic predator abundance, or mast availability, and (3) observe interspecific and intraspecific interactions. The city of Charleston was divided into eight habitat types including: old residential, park, university, wooded residential, new residential, commercial, industrial, and forest. Transects were surveyed for both species of squirrel during all four seasons beginning in spring 2008 to winter 2009. Due to diurnal nature of squirrels daylight hours were divided into three time periods: morning, afternoon, and evening. Each transect was surveyed 3 times during each season My results show that fox squirrels predominate in the urban landscape in Charleston, with roughly three times the abundance of gray squirrels (3.2:1). Two and three-way ANCOVAs suggest that fox and gray squirrels select different habitat types. Fox squirrels are choosing generally more open habitat with shade trees while gray squirrels are selecting wooded areas with understory. There are seasonal changes in the number of both species. Fall abundance was significantly different than the other seasons for fox.

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