66 Samuel I. Zeveloff and Phillip D. Doerr 



the lower nutritive value of winter browse. Both situations are, of 

 course, analogous to that occurring in many hibernators (e.g., Davis 

 1976). In raccoons, fat stores would become depleted in winter because 

 of (1) higher metabolic costs of staying warm, (2) more energetically 

 expensive foraging associated with greater reliance on predation (John- 

 son 1970), which is a more active type of foraging, and (3) reduced 

 overall food intake because of sparser food sources. Northern latitudes, 

 with colder temperatures and vegetation made less accessible by deeper 

 snows, should be the most energetically demanding places for raccoons 

 in the winter. This would explain the latitudinal differences in adult 

 weight loss. Other comparisons support this explanation. The periods of 

 yearling weight increase and adult weight decrease occur later in North 

 Carolina than in the northcentral states and are less extreme. Where 

 winter arrives later and is not as harsh, weight gains need not occur as 

 early to ensure survival. Instead, energy stores that last longer into the 

 winter should delay weight loss. 



Winter foods of raccoons might be of low nutritive value. But, 

 since raccoons are extremely omnivorous, this should be less a factor in 

 their weight changes than for those in obligatory herbivores like deer 

 (see Mautz 1978). Furthermore, since raccoons exhibit denning behav- 

 ior and often forage at night, when winds are typically less severe, they 

 might have lower winter energy demands per unit weight than deer. 

 Certainly, other factors such as the insulative quality of the fur and 

 physiological adaptations also need to be considered for a valid compar- 

 ison to be made. 



Finally, breeding activity in the later winter and early spring might 

 influence the pattern of adult raccoon weight decrease by causing a 

 further drain on fat stores. In a separate study (Zeveloff and Doerr 

 1981) we found a high negative correlation between mean body weights 

 and mean testis weights of 16 adult male raccoons from mid-January 

 through February 1976 (r = -0.99; P<0.01). This indicates that male 

 body weight decreases at a time of increased reproductive activity. To 

 fully understand raccoon body weight dynamics, one might consider 

 their reproductive events in addition to geographic variation in climatic 

 seasonality and food availability. 



ACKNOWLEDGMENTS.— R. A. Lancia, R. J. Monroe, L. C. 

 Ulberg, H. Underwood and J. R. Walters of NCSU and J. E. Cooper of 

 the North Carolina State Museum of Natural History provided useful 

 criticisms of this work. V. C. Schmidt, NCSU, helped prepare materials 

 for X-raying. L. Barbour of Smithfield, NC, permitted us to inspect 

 raccoon specimens at his fur business. This is paper number 857 1 of the 



