Raccoon Seasonal Weight Changes 65 



ing. Slopes and intercepts of the descending lines of adult male body 

 weight in January and February were similar in 1975 and 1976 (P>0.05, 

 F-test); the same was true of adult female body weights. The negative 

 slope of the pooled male sample was significant (r = -0.45; P = 0.01; N = 

 30) and the pooled female data also provided a clearly decreasing body 

 weight trend (r = -0.44; P = 0.08; N = 18). These adult weight decreases 

 in January and February were compared between sexes (F-test). Slopes 

 were similar (P>0.05) but intercepts were not (P<0.01), with males 

 being typically heavier. 



In Minnesota, Mech et al. (1968) reported a 50% weight decline in 

 adult raccoons from late November through mid-March followed by a 

 weight gain beginning in mid-April. Adult raccoon weights were also 

 found to be minimal in the spring in Michigan (Stuewer 1943a) and 

 Alabama (Johnson 1970). In Alabama, however, spring weights were 

 only about 20% less than those in the fall. We also found this midwinter 

 weight decline to be less extreme in North Carolina. In the pooled sam- 

 ple regressions, expected values of adult weight decreased by 22% for 

 males and 27% for females through January and February. Further, this 

 winter decline in adult raccoon weights begins about two weeks later in 

 North Carolina than it does in the northcentral states (see Stuewer 

 1943a; Mech et al. 1968). 



Body weights of juvenile male raccoons increased from the end of 

 July to mid-December 1975 (r = 0.71; P<0.05; N = 12), followed by an 

 insignificant decreasing trend through February 1976 (r = -0.43; P>0.05; 

 N = 5). Juvenile female weights also declined from mid-December 1975 

 through February 1976 (r = -0.65; P = 0.06; N = 9). Similarly, both 

 Stuewer (1943a) and Mech et al. (1968) found that body weights of 

 juvenile raccoons in Michigan and Minnesota increased until November 

 of their first year and then declined. We also observed yearling female 

 weights to increase from November 1975 through January 1976 (r = 

 0.85; P = 0.08; N = 5), another pattern consistent with those found 

 farther north by these authors. 



Iverson and Turner (1974) suggested that mammals lose weight 

 when it is adaptive to lessen energy requirements in certain seasons. 

 However, a weight decrease normally occurs by fat loss, which need not 

 imply lower energy requirements. Energy demands could even be rela- 

 tively high in fat depleted individuals. For example, raccoon weights are 

 lowest by winter's end, a time when energy requirements for upcoming 

 breeding events should be high. 



We suggest a less complicated explanation, which is simply that 

 animals put on weight while food is readily available to prepare them 

 for the harsher winter and early spring. Mautz (1978) argued that white- 

 tailed deer, Odocoileus virginianus, add fat in summer and fall to offset 



