Research Article Habitat Use of Fox Squirrels in an Urban Environment ROBERT A. MCCLEERY, 1 Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA ROEL R. LOPEZ, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA NOVA J. SILVY, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA SARAH N. KAHLICK, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA ABSTRACT Tree squirrels are one of the most familiar mammals found in urban areas and are considered both desirable around homes and, conversely, a pest. We examined fox squirrel (Sciurus niger) habitat use in inner city and suburban areas using radiotelemetry. We estimated habitat selection ratios at differing scales by season and fox squirrel activity. Telemetry data suggests that during periods of inactivity radiocollared fox squirrels (n ¼ 82) selected 1) areas with greater tree canopy, 2) live oaks (Quercus fusiromis and Q. virginiana), and 3) trees with larger diameters and canopies. When inactive during the winter and spring, fox squirrels also preferred, within their core areas, to use the inside of buildings, and during periods of activity in the autumn and spring, fox squirrels preferred grassy areas. During periods of activity, fox squirrels avoided using pavement but did not exclude it from their core-area movements. Fox squirrels’ ability to use buildings and to tolerate pavement in core-area movements make vast areas of the urban environment available to fox squirrels. In evaluating habitat variables that increased fox squirrel activity in urban areas, we found the number of large and medium trees, amount of pavement and grassy areas, canopy cover, number of oaks, and the area covered by buildings were all important factors in predicting fox squirrel activity in an urban environment. Our data suggests urban planners, animal damage control officials, wildlife managers, and landscapers who want to control urban fox squirrel populations through habitat manipulation should consider the reduction of oaks trees, a reduction of the canopy cover, and restricting the access of fox squirrels to buildings. Alternatively, home owners and squirrel enthusiasts hoping to bolster fox squirrel populations in urban areas should consider increasing the number of large mast–bearing trees and canopy cover and providing nest boxes. (JOURNAL OF WILDLIFE MANAGEMENT 71(4):1149–1157; 2007) DOI: 10.2193/2006-282 KEY WORDS fox squirrel, habitat use, Sciurus niger, synurbanization, urban wildlife. In the twenty-first century, natural landscapes are expected to continue their unprecedented 200-year alteration from rural to urban landscapes (Adams et al. 2006). Wildlife managers and scientists are attempting to prepare for these changes; however, there is only a cursory understanding and limited body of literature available for wildlife in urban areas (Wolch et al. 1995; Vandruff et al. 1996; Adams et al. 2005, 2006). Some wildlife populations, such as deer (Odocoileus spp.), squirrels (Sciurus spp.), and geese (Branta spp.) have managed to adjust to human-dominated landscapes by modifying their basic ecology through a process defined as synurbanization (Adams et al. 2005). Synurbanization usually leads to changes in population size, sex and age structure, survival, behavior, and habitat use (Gliwicz et al. 1994), making it ineffectual to manage urban populations with research conducted on wildlife populations in rural settings. Nonetheless, there is a lack of information even on the basic ecology of common wildlife species inhabiting urban areas. For simplicity, we defined these urban areas as places of relatively dense human population, where most of the land is dedicated to buildings, concrete, grassy lawns, and other human uses (Adams et al. 2006). Tree squirrels (Sciurus spp.) are highly visible in urban areas of North America where some residents consider them desirable around their homes and others, conversely, consider them a pest (Brown et al. 1979, Gilbert 1982, Conover 1997, Adams et al. 2006). Nonetheless, there is still much to be learned (Williamson 1983, Vandruff and Rowse 1986, McPherson and Nilon 1987, Salisbury et al. 2004) about tree squirrels’ use of urban habitats, especially by fox squirrels (S. niger), a common tree squirrel found in cities throughout the midwest (Adams 1994) and southern (Flyger 1974) United States. We are only aware of one study that has examined urban habitat use by the fox squirrels in fragmented woodlots (Salisbury et al. 2004), and we are unaware of any studies of fox squirrels’ usage of the biotic and abiotic substrates commonly found in inner-city and suburban areas. Such habitat information can be used by wildlife managers, urban planners, animal damage control officials, homeowners, and squirrel enthusiasts to attract or manage fox squirrel populations through the manipulation of the urban environment. Diverging from traditional habitat use studies that look strictly at the biotic environment (e.g., Kantola and Humphrey 1990, Lopez et al. 2004, Perkins and Conner 2004), we evaluated fox squirrels’ interactions with the biotic and abiotic features unique to urban environments (e.g., buildings, planted and ornamental trees, concrete, and exotic manicured grasses; Adams 1994). Our study objectives were to 1) understand fox squirrel use of space in relation to the urban substrates, 2) determine tree characteristics selected by fox squirrels during periods of activity and inactivity, and 3) develop a model to understand what features in the urban environment affect levels of fox squirrel activity. STUDY AREA We conducted research on the Texas A&M University main campus (140 ha) in College Station, Texas, USA. The campus was comprised of a diversity of urban habitats ranging from inner city areas to more typical suburban areas (Fig. 1). The center of our study area was covered with a 1 E-mail: bmcc@tamu.edu. McCleery et al.  Urban Fox Squirrels 1149