126 James L. Boone and Joshua Laerm 



METHODS 



We captured small mammals with Sherman livetraps in north- 

 eastern North Carolina for studies examining subspecific affinities, 

 population genetics, and Lyme disease (Magnarelli et al. 1992) in P. 

 gossypinus. On 26 and 27 April 1990, we trapped in the Dismal 

 Swamp along Highway 158 from 6.3 to 10.6 km east of Highway 32 

 (east of Sunbury, Gates County, North Carolina) for 587 trapnights. 

 On 13 June 1990, we placed 200 traps in the Chowan Swamp between 

 2.9 and 5.3 km south of Gatesville (Gates County, North Carolina). 

 On 28 and 29 April 1990, we trapped along the Cashie River in and 

 around Windsor (Bertie County, North Carolina) for 350 trapnights, 

 and we placed 150 traps in and around Richlands (Onslow County, 

 North Carolina) on 30 April 1990. 



Locations of trap lines and specific traps were selected to maxi- 

 mize the capture of P. gossypinus based on our understanding of 

 its habitat preference and ecology learned from the capture of more 

 than 2,100 cotton mice from throughout its entire range. Although 

 these mice can be caught almost anywhere, they seem to exist in 

 highest densities in thick, undisturbed (anthropogenic or natural), sea- 

 sonally flooded, riparian woodlands near water. On coastal barrier 

 islands where these habitats do not exist, they seem to occur most 

 densely in undisturbed old-growth oak-palmetto (Quercus sp. and 

 Serenoa repens) forests. Traps were set on, in, and under logs, in 

 trees, under stumps, in the rotten bases of trees, on the edges of 

 ponds, on floating debris in flooded forests, as well as in old build- 

 ings and trash piles. More than one trap was set in particularly pro- 

 mising sites. 



We used allozyme markers to identify the Peromyscus. Genetic 

 analysis was performed with standard horizontal starch gel electro- 

 phoretic and protein staining techniques on blood, liver, and muscle 

 for 42 enzyme and protein loci. Techniques were similar to those of 

 Selander et al. (1971) as described in Boone (1990). 



Body mass was measured to the nearest 0.1 g. Age (juvenile, 

 subadult, or adult) was determined by pelage color, and reproduc- 

 tive status was determined by examination of external and internal 

 reproductive structures. Non-adult and pregnant females were deleted 

 from morpholo-gical comparisons. 



RESULTS 



Peromyscus gossypinus was captured in each of the four areas 

 examined, and P. leucopus was captured in all areas except Rich- 

 lands (Table 1). Additionally, one golden mouse (Ochrotomys nuttalli 

 Harlin) and one juvenile Virginia opossum (Didelphis virginiana 



