Great Dismal Swamp Cotton Mice 



127 



Table 1. Peromyscus gossypinus and P. leucopus captured in North Carolina, 

 1990. 



Location 



Species 



P. gossypinus 



P. leucopus 



Captures/ Captures/ 



dumber « nnn Number 1 nnn 



cau S ht tracts cau 8 ht trap'nThts 



Gates County Dismal Swamp 

 Gates County Chowan Swamp 

 Bertie County Windsor 

 Onslow County Richlands 



5 



8.5 



27 



46.0 



42 



210.0 



2 



10.0 



33 



94.3 



5 



14.3 



42 



280.0 







0.0 



Kerr) were captured in the Dismal Swamp, and one Blarina was 

 captured at Windsor. 



We found that Dice's (1940) suggestion that these Peromyscus 

 species can be distinguished by size is not strictly true. Our comparison 

 of genetic markers and morphology indicates that although P. gossypinus 

 tends to be larger and heavier than P. leucopus, there is considerable 

 overlap. For the mice caught east of Sunbury, body mass of P. gossypinus 

 ranged from 20.9 to 35.5 g (x = 26.3 g, n = 5), whereas P. leucopus 

 ranged from 14.6 to 24.6 g (x = 19.1 g, n = 26). In the Chowan 

 Swamp, body mass of P. gossypinus ranged from 17.1 to 36.8 g, 

 ( x = 25.9 g, n = 42); the one adult P. leucopus weighed 15.9 g. In 

 the Windsor area, P. gossypinus ranged from 19.2 to 37.9 g (x = 

 28.4 g, n = 22), and P. leucopus ranged from 17.1 to 24.1 g (x = 

 20.4 g, n = 4). The P. gossypinus from Richlands ranged from 21.2 

 to 39.4 g (x = 29.2 g, n = 33). Therefore, if Rose et al. (1990) 

 used size to identify Peromyscus, some of the specimens identified as 

 P. leucopus by might actually have been P. gossypinus. 



DISCUSSION 



Our results probably differ those of Rose et al. (1990) as a 

 result of different trapping location, design, and methods. In the southern 

 portion of the Dismal Swamp, Rose et al. (1990) used pitfall traps 

 set on a grid. We used only Sherman livetraps, and our collection 

 locations were selected to target habitats thought to be optional for 

 P. gossypinus without concern for determining density or other demo- 

 graphic parameters. Therefore, we were not confined to a grid, and 

 we were able to trap in areas, and place traps in sites, that would be 

 inappropriate to use with pitfall traps in a demographic study. Further- 

 more, our trapping was only conducted in the southernmost part of 



