Small Mammals in Great Dismal Swamp 
97 
The arboreal P. 1. leucopus and O. n. nuttalli are common today, as 
in the past, and so is B. brevicauda (Table 4). The species showing the 
largest numerical increases in collections conducted during this decade, 
including the results of Rose (1981a), were S. 1. fisheri, S. c. helaletes, 
and R. h. humulis (Table 4). That substantially larger numbers were 
recorded has two causes: the use of different trapping methods and the 
greater sampling effort in nonforested habitats (Table 2). Early studies 
relied heavily on snap or break-back traps. In our research, all 44 S. I 
fisheri were taken with pitfall traps (Table 1), an expected result because 
this shrew is rarely collected by any other means (Rose 1980), and most 
R. h. humulis (93%) were taken in live traps. These two methods yielded 
all S. c. helaletes (Table 1). 
The Dismal Swamp southern bog lemming, S. c. helaletes , a 
distinctive relict subspecies, remains enigmatic as a study subject. We 
noted the cuttings and green dropping of this species at the start of the 
study on one live-trap grid, but we did not catch any S. c. helaletes until 
the tenth month of trapping, after which we caught 1 1 in the span of a 
few weeks on that grid. Pitfall trapping yielded S. c. helaletes from 
nearly half of the nonforested grids, and we determined that it sometimes 
was common. The same can be said of the Dismal Swamp southeastern 
shrew, S. 1. fisheri ; it was found on more than half of the pitfall grids 
and it, too, was locally abundant, especially in habitats in early succession. 
Thus, we determined that these two supposedly rare species, whose 
status was a particular objective of the pitfall trapping, were widespread 
and sometimes common. However, because the upland subspecies of the 
southeastern shrew, Sorex longirostris longirostris Bachman, is found 
nearby, S. /. fisheri has been listed by the USFWS as threatened (FR 
51,287: 26 September 1986). That decision was made because the drying 
conditions created by ditching and draining may favor the movement of 
the S. I longirostris into the Dismal Swamp, thereby potentially resulting 
in interbreeding and perhaps genetic swamping of the restricted and less 
common S. 1. fisheri. On the other hand, S. c. helaletes has never been 
Federally listed, because it is widespread (1,000-km 2 area), colonizes 
early-successional stages and persists there until the forest matures, is 
locally abundant, and is isolated by 300 km from the nearest conspecific 
subspecies. Thus, although S. c. helaletes was believed by some investiga- 
tors to be extinct, it apparently is thriving. 
The second reason that we were able to collect these three species in 
numbers indicating that they are common is that the live- and pitfall- 
trapping studies focused on nonforested habitats (Table 2). Overall, 91% 
of S. /. fisheri and 100% of R. h. humulis and of S. c. helaletes were 
taken from nonforested habitats. These habitats ranged from fields with 
purely herbaceous vegetation to natural or planted stands of trees up to 
