Notes on Eastern Hognose Snake 



53 



CO 







03 

 O 

 CO 



"co 



"D 



D 

 03 

 O 



_q 



CO 







-Q 



E 



60 



55 



50 



45 



40 



35 





• male • 



a a 



a o D o 

 a aaa a 



a a a 



a 



a an 



a 

 a a 



female 



120 125 130 135 140 145 



Number of ventral scales 



150 



Fig. 1. Scale counts used to sex 66 Heterodon platy rhinos individuals found on 

 Assateague Island, Virginia, June-September 1981. 



Females were significantly longer (t = 3.8, df = 64, p < 0.02) and 

 also exhibited greater body mass (t = -2.74, df = 64, p < 0.01) than males 

 (Table 1). Covariance analysis was used to scale body mass for differen- 

 ces in snout-vent length, using SVL as the covariate. Female H. platy- 

 rhinos were no heavier than males of the same SVL (F i, 6 3 ) = 2.61, p > 

 0.10). Sexual dimorphism in body length has been described in several 

 populations of Heterodon (Edgren 1961, Piatt 1969) and for other spe- 

 cies (Fitch 1981, Gibbons 1972, Shine 1978). Piatt (1969) attributed the 

 sexual size dimorphism in H. platyrhinos to faster growth rates in 

 females. Larger females of some species produce larger clutches, thereby 

 possibly promoting selection for increased body size in females (Shine 

 1978, Semlitsch and Gibbons 1982). 



Of the 66 individuals captured, 55 were judged to be normal in 

 coloration, 3 were melanistic, and 8 were intermediate (very dark with 

 some light markings). All melanistic snakes were adults. Observations 

 on the number of dorsal blotches revealed that females have more 

 blotches than males (t = 4.22, df = 64, p < 0.001; Table 1). Moreover, 

 these means were also different (more than 2 SE) from values reported 



