Influence of Age, Sex and Time of Year on Diet of the Bobcat (Lynx Rufus) in Pennsylvania
McLean, Meredith L., McCay, Timothy S., Lovallo, Matthew J., The American Midland Naturalist
Diet of the bobcat (Lynx rufus) in the mid-Atlantic region of the United States is poorly known. Age, sex and time of year are thought to influence bobcat prey selection, but accounts vary. We examined the contents of 85 bobcat stomachs taken from Pennsylvania during autumn and winter 2000-2002. White-tailed deer (Odocoileus virginianus) and rabbits (Sylvilagus sp.) occurred most frequently as prey. A larger percentage of female bobcats consumed lagomorphs (28%) than did males (12%; P = 0.04). More male bobcats consumed meso-mammals (14%), including raccoons and porcupines, than did females (2%; P = 0.04). Diet did not differ between bobcats <2 y and bobcats ≥2 y. Variety of prey eaten was larger in autumn than in winter. Sexual differences in diet may be related to sexual dimorphism in this species and may help to effect interspecific niche partitioning. Winter weather reduces the availability of certain prey items in this region and may decrease the bobcat's ability to travel and hunt effectively.
The diet of the bobcat (Lynx rufus) has been studied throughout much of North America (Anderson and Lovallo, 2003), including New England (Hamilton and Hunter, 1939; Pollack, 1951; Westfall, 1956; Litvaitis et al., 1984) and the southeastern United States (Progulske, 1955; Story et al., 1982; Maehr and Brady, 1986; Baker et al., 2001). The primary foods of the bobcat in these areas are lagomorphs, small rodents and white-tailed deer. White-tailed deer are more commonly consumed in New England than in the Southeast; whereas small mammals are more commonly consumed in the Southeast (Anderson and Lovallo, 2003). With the exception of a study by Fox (1990), there is a paucity of information regarding the diet of the bobcal in the Mid-Atlantic States-including Virginia, West Virginia, Maryland, Delaware, Pennsylvania, New Jersey and New York.
The bobcat diet varies by age, sex and season (Anderson and Lovallo, 2003). Adult bobcats are larger and likely have greater hunting skills than younger bobcats, allowing them to prey upon more diverse and larger prey (Fritts and Sealender, 1978; Litvaitis et al., 1984; Matlack and Evans, 1992). Similarly, sexual dimorphism of bobcats may allow males to be more efficient hunters of deer and other large mammals (Litvaitis et al., 1984; Matlack and Evans, 1992). Finally, snow cover may limit both the bobcat's hunting range and the ability of white-tailed deer to escape predation by bobcats (Fritts and Sealander, 1978). Knowledge of the factors that can affect bobcat diet can aid in understanding intraspecific resource partitioning and habitat quality. We studied the diets of bobcats taken in Pennsylvania during autumns and winters of 2000-2001 and 2001-2002.
We obtained 85 bobcat stomachs from road-killed (n = 7) and legally harvested (n = 78) animals from 17 counties in Pennsylvania. Date of death was collected from hunter surveys for harvested animals and was estimated for road-killed bobcats. Sex of bobcats was determined from gross examination. Age was determined using the cementum-annulus method (Crowe, 1972, 1975). Canine and molar teeth were extracted and sent to Matson's Lab, LLC (Milltown, MT) for analysis.
Volume of the stomachs was measured by water displacement before dissection. Prey items were determined macroscopically when possible. Bones, particularly jaws, were useful in identification. However, the primary method of prey identification was microscopic examination of hair cuticle patterns following the methods of Brunner and Coman (1974), except that acetyl acetate was used rather than Gelva for the cuticle impressions. Hairs were determined to species by comparing cuticle patterns to those in Adorjan and Kolenosky (1969), Brunner and Coman (1974) and a reference set in the zoological collections of Colgate University.
Bobcats were grouped according to sex and age. Each animal was placed in one of two age-groups reflecting phases in predatory ability (Fritts and Sealander, 1978): juvenile (<2 y) and adult (≥2 y). …