Banisteria, Number 50, pages 3-9 © 2018 Virginia Natural History Society Natural History of the Southern Bog Lemming in Southeastern Virginia Robert K. Rose Department of Biological Sciences Old Dominion University Norfolk, Virginia 23529-0266 email: [email protected] ABSTRACT The isolated subspecies of Southern Bog Lemming of southeastern Virginia, Synaptomys cooperi helaletes, has been studied extensively since its “rediscovery” in the Great Dismal Swamp in 1980. Multiple studies using pitfall traps, starting in the Great Dismal Swamp National Wildlife Refuge and then extending elsewhere in southeastern Virginia and adjacent northeastern North Carolina, have revealed lemmings to be much more widespread and often more common than previously believed, with their presence now confirmed as far west as Surry and Sussex counties, about 30 km east of Petersburg, Virginia. When present, lemmings often are among the most numerous members of the small mammal community. Even in appropriate habitat, its presence seemingly is determined by its proximity to another arvicoline rodent, the Meadow Vole, Microtus pennsylvanicus, which usually is larger and perhaps competitively and behaviorally dominant. Keywords: competition, meadow vole, Microtus pennsylvanicus, Synaptomys cooperi. INTRODUCTION the genus, Synaptomys borealis, overlaps with S. cooperi only in the southern parts of its distribution, which The Southern Bog Lemming, Synaptomys cooperi, is extends beyond the Arctic Circle. Much more is known a short-tailed rodent in the family Muridae, subfamily about the biology of Synaptomys cooperi because Arvicolinae (formerly Microtinae), a subfamily with a population studies have been conducted in eastern worldwide distribution in the northern latitudes, and Kansas (Gaines et al., 1977), eastern Illinois (Beasley & includes the only rodents active year-round in high Getz, 1986), western Virginia (Linzey, 1984), and Arctic environments. Synaptomys cooperi is distributed southeastern Virginia (Rose & Lord, 2012). Across its in eastern North America from the Canadian maritime distribution there are hints that the Southern Bog provinces westward to southern Manitoba and western Lemming is more able to coexist with Prairie Voles Minnesota, southward through the eastern part of the 0Microtus ochrogaster) than with Meadow Voles (M. Great Plains, and eastward in the cooler montane habitats pennsylvanicus). of the southern Appalachians. Isolated populations are known from Meade County in southcentral Kansas, GENERAL CHARACTERISTICS Dundy County in southwestern Nebraska, the Great Dismal Swamp region of southeastern Virginia and The Southern Bog Lemming is a thick-bodied, short¬ adjacent North Carolina, and the Pine Barrens region of tailed rodent with grizzled brownish fur above and gray New Jersey. C. H. Merriam (1896) believed the Southern fur below (Lig. 1). Each sex of S. c. helaletes averages Bog Lemmings discovered in the Great Dismal Swamp about 28 g, with some individuals weighing up to 47 g to be distinctive from others and thus named it a new (Rose, 2006; Rose & Lord, 2012). Rose (2006) found the species, Synaptomys helaletes, but later this taxon was sex ratio of S. c. helaletes is 1:1, and both sexes have relegated to subspecies status (Wetzel, 1955), so it is similar total lengths, about 120 mm, of which the tail now called Synaptomys cooperi helaletes. is about 20 mm. Its tail is about as long as the hind Baird (1858) proposed the name Synaptomys because foot, and only half as long as that of its closest relative in he believed its features represented a link between true southeastern Virginia, the Meadow Vole. Its blunt lemmings (Lemmus) and mice. The one other species in snout hides a pair of grooved upper incisors, a feature 4 BANISTERIA NO. 50, 2018 Chesapeake, and Suffolk (all former counties) and as far west as Isle of Wight County, where they were caught in pitfall traps at eight of 14 sites (Rose, 2005). Later, evidence of populations was detected at 10 sites farther west, in Southampton, Surry, and Sussex counties, and confirmed when Southern Bog Lemmings were caught in live traps at three of five locations in these counties (Rose, 2011). Their presence in western Surry and Sussex counties, within 30 km of Petersburg, Virginia, suggests that Southern Bog Lemming populations might be found even farther west. With the addition of these three counties, the known distribution of S. cooperi helaletes has been extended to 7,000 km2 (2,700 mi2), much Fig. 1. Photograph of Southern Bog Lemming, Synaptomys broader in Virginia than previously believed. cooperi (credit Wayne Van Devender). FORM AND FUNCTION distinguishing this rodent from others of similar size in As in other arvicoline rodents, the dense fur, short southeastern Virginia. Its small ears are nearly obscured tails, and short ears are adaptations for conserving heat by the long fur and the eyes also are small. in the north temperate environments in which most populations of Southern Bog Lemmings live. The same DISTRIBUTION features that conserve heat create heat-dumping problems in summer for boreal species living in Like the other isolated subspecies, Synaptomys temperate locations, probably resulting in them cooperi helaletes was believed to have a restricted becoming more nocturnal during the warmest months in distribution, probably limited to the historic Great order to avoid life-threatening heat stress. For Southern Dismal Swamp of Virginia and North Carolina, which Bog Lemmings, information on such behavioral changes when Europeans colonized Virginia may have had an is unknown but adjustments in the timing of their area of 1,800 km2 (Lewis & Cocke, 1929). The Great breeding season are suggestive (see Reproduction). Dismal Swamp, a distinctive geological feature of the The distinctive feature of the alimentary canal is the mid-Atlantic coast, developed during the Holocene and large spiral-shaped caecum, useful in the foregut is characterized by peaty soils, high water table, fermentation that is crucial to extracting energy from especially in winter, and cooler and wetter habitats than their low-caloric foods, such as grasses, sedges, and in nearby uplands, qualities that likely enabled S. c. mosses. Other arvicoline rodents have large caeca, but helaletes to survive in place after the last Pleistocene only the caecum of the Southern Bog Lemming has the glacier retreated northward starting about 10,000 years spiral shape, a feature that increases the surface area ago, taking with it most other boreal species. without increasing the capacity of the caecum. The Synaptomys cooperi helaletes was discovered when caecum slows the flow of digesta through the gut, the U.S. Bureau of Biological Survey sent a team, headed allowing microbial action and fermentation sufficient by A. K. Fisher, to conduct a survey of plants and time to break down and release simple sugars and amino animals in the Great Dismal Swamp. From 1895 to 1898, acids for absorption in the small intestine. It is unclear Fisher’s team spent a total of 23 weeks collecting many why the spiral-shaped caecum is present in Synaptomys kinds of organisms there, including 23 Southern Bog but not in other arvicoline rodents. Lemmings in kill traps. Later efforts to find lemmings in The efficiency of digestion is increased by Southern the Swamp were futile, including multiple efforts by Bog Lemmings practicing coprophagy (i.e., the eating of Smithsonian Curator Charles O. Handley (1979), until feces). Soft pellets, plucked before they drop to the Rose (1981) collected 13 Southern Bog Lemmings in ground, are swallowed after chewing, and their second pitfall traps at three locations in the northwest section of passage through the alimentary canal extracts nitrogen the Great Dismal Swamp National Wildlife Refuge and water, and retains more minerals than initial (hereafter “Refuge”) in late winter of 1980. Later studies digestion (Kenagy & Hoyt, 1980). Coarse pellets with extending outward from the Refuge revealed Southern undigestible fibers, the product of the second passage, Bog Lemmings at numerous locations in Virginia Beach, are allowed to drop to the ground at latrines. ROSE: SOUTHERN BOG LEMMING 5 Like other arvicoline rodents, S. c. helaletes is active There is little information on reproduction from other year-round and thus must find the calories to sustain populations or subspecies of S. cooperi. Connor (1959) itself day to day. Fat stores probably play a minor role in attempted to breed Southern Bog Lemmings in the winter survival because Southern Bog Lemmings (also laboratory but only one female produced litters (n = 6) Prairie and Meadow Voles) have little body fat at any and a total of 22 young during a 26-week period. The time of year (pers. obs.). Arvicolines, and presumably average interval between litters was 23-26 days, S. c. helaletes, have high metabolic rates, higher than indicating a post-partum estrus and breeding soon after rodents of similar size that live in more temperate the birth of a litter, a common feature in arvicoline locations. The reasons for their high metabolic rates are rodents. Much remains to be learned about the patterns not entirely understood but may be related to their high of reproduction in the geographic populations of biotic potential, such as their ability to double population Southern Bog Lemmings. size in as little as a month via their short gestation and nursing periods. Many arvicoline rodents, including ECOLOGY Southern Bog Lemmings, undergo multi-annual population cycles; in eastern Kansas, populations of S. c. Although Synaptomys cooperi sometimes is found in gossii underwent multi-year cycles on two sample grids forests (Krupa & Haskins, 1990; Linzey, 1983), its diet but had annual cycles on a third grid (Gaines et al., is composed almost exclusively of herbaceous 1977). No pattern was evident in the population study of vegetation (Linzey, 1984; Rose & Ford, 2012), including S. c. helaletes in Suffolk, Virginia (Rose & Ford, 2012). mosses and fungi, but mostly grasses and sedges, plants After nearly a century of study, the reasons for multi¬ rarely found in forests with closed canopies. Fruits of year population cycles in arvicoline rodents remain huckleberries and blueberries were important foods in unclear (Krebs, 2013). New Jersey and bark and roots were eaten sometimes too (Connor, 1959). In southwestern Virginia, broomsedge REPRODUCTION CSchizachyrium scoparium) was the most important food during summer and mosses in winter (Linzey, 1984). In Litter size of necropsied S. c. helaletes females (n = the only study of diet of S. c. helaletes from southeastern 9) collected in pitfall traps was 2.56, but some other Virginia, feces obtained from 3-7 lemmings each season females had same-sized placental scars numbering showed that seeds and sedges dominated the winter diet; 4, 5, and 6; these values conform with litter sizes in in spring, sedges remained important but significant other subspecies (Rose, 2006). Pregnant females were amounts of grasses and mosses were also eaten (Rose & recorded for all months from November through June, Ford, 2012). The summer diet was nearly 80% cane but none from July-October. This suggests that Southern (.Arundinaria sp.), with seeds and sedges comprising Bog Lemmings in southeastern Virginia may suspend most of the rest. In autumn the diet was more varied, with breeding during the warmest months, perhaps because of cane and grasses combining for about 80%, followed by problems with dealing with summer heat. Although the sedges, lichens, and seeds. In this study, soft rushes November-June pattern of reproduction seen in females ([Juncus spp.) were sometimes consumed, but were never is not as clear for male S. c. helaletes, the absence of more than 5% of seasonal diets. By contrast, in habitat epididymal convolutions from July-September indicates under powerlines in the Dismal Swamp, Rose & that males were infertile during this period. The winter Stankavich (2008) sometimes found piles of the breeding of Southern Bog Lemmings in southeastern spaghetti-like pith of Juncus left after Southern Bog Virginia is different from northern populations, where Lemmings had peeled and eaten the green cover from breeding usually is suspended in mid-winter (Linzey, this soft rush; this behavior seemed to be more common 1983). Part of the reason for continued winter breeding in winter. The discarded 3-4 cm sections of cane near of S. c. helaletes may relate to the continual growth of latrines of green feces indicate its frequent consumption grasses, sedges, and softrushes during the mild winters by Southern Bog Lemmings in southeastern Virginia. in southeastern Virginia, where the mean January high Most plants in the diet are found in damp or wet temperature is 9° C. Using external features only, S. c. environments and some, such as the sedges (Carex), soft helaletes near the Refuge in Suffolk (Rose & Ford, 2012) rushes (Juncus), and spikerushes (Eleocharis), are showed high levels of reproductive readiness throughout obligate wetland plants. the 18-month study: 84% of adult females showed two The presence of Southern Bog Lemmings in these of three reproductive features and 52% of males had habitats often is indicated by 3-4 cm cut and discarded descended testes; monthly values did not depart greatly sections of grasses, sedges, or cane and by latrines with from these values, suggesting year-round reproduction. their distinctive green feces. These fecal pellets are 5-6 6 BANISTERIA NO. 50, 2018 mm long and 2-3 mm wide and rounded at both ends, in species, such as Microtus. effect sausage-shaped (Rose, 2016). The reasons for the Other studies besides Rose & Ford (2012) also feces being green are unknown, but may relate to the indicate that S. c. helaletes does not compete well with unique spiral-shaped caecum. Meadow Voles in southeastern Virginia. Of the 38 study In southeastern Virginia, Southern Bog Lemmings grids located in and near the Refuge, the 17 grids with are part of some small mammal communities but not Southern Bog Lemmings (n = 102) yielded only two others, even in appropriate habitats. One reason may Meadow Voles (Everton, 1985; Rose, 2006). In Isle of be due to its competitive abilities with other species. Wight County, either Meadow Voles or Southern Bog Evidence that S. c. helaletes does not compete well Lemmings were present on 12 of 14 grids but both with Meadow Voles was seen in the study in which species were found on only three grids (Rose, 2005), and they and Woodland Voles (Pitymys pinetorum) were when the latter species was present, only 1-2 Meadow co-dominants in a regenerating pine plantation in the Voles were trapped. In general, when Southern Bog absence of Meadow Voles (Rose & Ford, 2012). After Lemmings are present, Meadow Voles usually are not. mature pines were logged on the site, located 2 km west For example, Everton (1985) caught lemmings on 11 of the Refuge in Suffolk, the stumps and logging debris grids, but only one Meadow Vole in these wet sites. were bulldozed into parallel windrows about 40 m apart. Thus, mounting circumstantial evidence is accumulating Loblolly pine seedlings were mechanically planted in the that Southern Bog Lemmings in Virginia do not compete peaty soils, with furrows between rows that filled with well with Meadow Voles, to the point that they are water after heavy rains and for much of the winter. These absent in habitats with many Meadow Voles and thrive conditions were tolerated by Southern Bog Lemmings only in their absence. and Woodland Voles, which reached modest densities, Additional information on their habitats in but none of the larger herbivorous rodents in the southeastern Virginia is provided by field studies in pine region (Meadow Voles, Hispid Cotton Rats [Sigmodon plantations in Isle of Wight County (Dolan & Rose, hispidus], and Marsh Rice Rats [Oryzomys palustris]) 2007), where S. c. helaletes was absent in stands of ages was ever trapped during this 18-month field study in 1, 8, 18, and 24 years: none was caught on 56 0.25-ha which Fitch live traps (Rose, 1994) were used. We did grids despite 39,600 traps nights with live traps and catch seven Eastern Harvest Mice (Reithrodontomys 28,500 trap nights with pitfall traps. This is the same humulis), but none during the last 15 months. In all, we county in which Southern Bog Lemmings were found in caught and tagged 47 Southern Bog Lemmings, 110 eight of 14 grids set in the more varied habitats under Woodland Voles, and 15 Short-tailed Shrews (.Blarina powerlines (Rose, 2005). brevicauda), resulting in densities of up to 14 Southern Even in appropriate habitat and in the absence of Bog Lemmings per hectare on one 0.55 ha grid and 32 Meadow Voles, Southern Bog Lemmings have patchy Woodland Voles per hectare on the other grid. distributions. But when they are present, they often are In field studies near Blacksburg, Virginia, Linzey among the most numerous small mammal in that (1984) presented evidence, based on removal community (Rose, 2006). In a pitfall study conducted in experiments and patterns of co-occurrence, that and near the Refuge, Southern Bog Lemmings were Synaptomys cooperi stonei is not successful in present in 17 of 21 0.25-ha grids, and lemmings (n = 102) competition for space with Meadow Voles. In another were second in abundance to Southeastern Shrews, Sorex field study, S. c. stonei was a regular occupant of longirostris (n = 114) on those 17 sites (Everton, 1985; clearings in the 4,450-ha Robinson Forest in Rose, 2006). southeastern Kentucky until Meadow Voles migrated Synaptomys cooperi helaletes often does not readily southward into this region, after which it has largely enter live traps. For example, Rose & Stankavich (2008) replaced Southern Bog Lemmings in these forest observed that latrines with green feces were common but clearings except when densities of Meadow Voles are Southern Bog Lemmings were not trapped until the 10th low (Krupa & Haskins, 1990). In the New Jersey month of biweekly live trapping in the Dismal Swamp; Pinelands, Shenko et al. (2012) also found populations then 13 different lemmings were tagged over the next of Southern Bog Lemmings, primarily in wet grassy few weeks. Linzey (1984) had such low recapture areas, in the almost complete absence of Meadow Voles. success after a year of trapping Southern Bog Lemmings By contrast, Danielson & Gaines (1987) report that with small Sherman traps that she used unbaited S. c. gossii in eastern Kansas shows no evidence of dropping boards to determine relative abundance and microhabitat selection, and thus is a habitat generalist, spacing patterns thereafter. I believe that S. c. helaletes being able to survive on the sidelines when the more is more prone to entering live traps during winter, productive habitat is occupied by more competitive perhaps finding the mixed seed baits worth the risk of ROSE: SOUTHERN BOG LEMMING 7 entering Fitch live traps then but not at times when their BEHAVIOR energy requirements are more easily met. The patchy distributions and reluctance of Southern Bog Lemmings I have found the Southern Bog Lemming to be more to enter live traps inhibit efforts to understand their role docile than most rodents, and easily handled after in rodent communities in southeastern Virginia. removal from live traps. When placed in the bottom of a In January and February of 2011,1 tested the idea that bucket, it is more likely to sit on its haunches, “rest,” or green feces could be used to accurately predict the nibble on seeds rather than to “run laps” around the presence of S. cooperi (Rose, 2011). I carefully searched perimeter, as most rodents do at first capture. By 27 sites across Southampton, Sussex, and Surry counties contrast, a Meadow Vole of similar size often will sit on in southeastern Virginia, places with grassy and sedge its haunches, raise its snout skyward while baring its habitats suitable for Southern Bog Lemmings but beyond teeth and squeak, in an aggressive posture. their known distribution. I spent 1-3 hours at each site, It is unclear whether Southern Bog Lemmings make and detected latrines with green feces at 10 sites, and maintain runways, as many arvicoline rodents do, indicating their possible presence. Then I placed baited but they do leave the characteristic piles of clippings and Fitch live traps at five of these 10 sites, and in two nights use latrines, usually along runways. The discarded of trapping caught four Southern Bog Lemmings at three clippings have diagonal cuts on the ends, and average of these sites, confirming that green feces are a good 3-4 cm for Southern Bog Lemmings, similar lengths to predictor of their presence. In late June 2014, I applied those cut by Meadow Voles but shorter by half compared the same methods to determine whether the two isolated to Cotton Rat cuttings. The cuttings of the lower sections subspecies in the Midwest were still present. After of grasses and sedges are discarded, probably because spending a day searching for green feces at each of the they are more fibrous and less nutritious, and seemingly localities in Kansas and Nebraska where the isolated only the upper sections and their seeds are consumed. subspecies of Synaptomys cooperi had been discovered, We can imagine a Southern Bog Lemming sitting on its I found no evidence for S. c. paludis at the fish hatchery haunches, cutting, discarding, repeating both many near Meade, Kansas, but multiple evidences of S. c. times, and finally consuming the younger, fleshier and relictus at and especially downstream from the fish (probably) more nutritious upper sections and seeds of hatchery near Parks, Nebraska. grasses and sedges, all the while sitting at the base of a From 2002 to 2012, my students and I conducted clump of grass or sedge, mostly protected from view by monthly live trapping on 1-ha grids to evaluate the small birds of prey. mammal communities at two sites in southern The blunt appearance of the snout is accentuated Chesapeake. These old fields were dominated by grasses when the facial hairs are directed forward. The that had vegetated abandoned farm fields, mostly placement and function of these vibrissae is not entirely bluestem (,Andropogon virginicus) and panic grasses understood in mammals but undoubtedly relates to (.Panicum spp.), plants that Everton (1985) reported collecting information on their closest environment, having the highest total contacts in association with the where their senses of touch and smell likely become presence of Southern Bog Lemmings. Some places on more important than vision. the grids were wet and harbored clumps of soft rushes, spikerushes, and wool grass (Scirpus cyperinus). REMARKS Meadow Voles were common on both grids, reaching high densities of ca. 50/ha on one grid and over 150/ha The reasons for the isolation of Synaptomys cooperi on the other, and hispid cotton rats were common too, populations being sufficiently long for them to have but in all of these years of trapping we never caught any diverged to become subspecies remain enigmatic, S. c. helaletes. I believe this is the strongest evidence, although the speculation that persistence and divergence together with Rose & Ford (2012), that the lemming are related to consistent or reliable water sources, populations cannot persist with populations of Meadow whether springs (in Kansas and Nebraska) or swamps (in Voles. Despite one or two individuals of each species Virginia and New Jersey), is plausible. Equally in need sometimes being taken on the same pitfall grid, in of explanation is how S. c. gossii, the Midwest general, if S. c. helaletes is present, Meadow Voles subspecies, became adapted to life in the mesic-to-xeric usually will be absent. It is entirely circumstantial grasslands of Kansas and Illinois, where thriving evidence for S. c. helaletes, but studies over the years populations have been studied extensively. Lurther, the have increasingly supported that contention. Midwest subspecies seems to be readily trappable, in BANISTERIA NO. 50, 2018 contrast to the isolated population in New Jersey, where Danielson, B. J., & M. S. Gaines. 1987. Spatial patterns Connor (1959) caught only 48 Southern Bog Lemmings in two syntopic species of microtines: Microtus in his four-year field study using Sherman traps. Linzey ochrogaster and Synaptomys cooperi. Journal of (1984) ceased trapping in western Virginia after one year Mammalogy 68: 313-322. in favor using dropping boards, and Rose & Stankavich (2008) observed the characteristic green feces in Dolan, J. D., & R. K. Rose. 2007. Depauperate small southeastern Virginia for nearly a year before the first mammal communities in managed pine plantations in lemming was trapped. eastern Virginia. Virginia Journal of Science 58: 147- In conclusion, except for its smaller size, Synaptomys 163. cooperi helaletes, the Southern Bog Lemming of southeastern Virginia, is typical in many ways to the Everton, R. K. 1985. The relationship between habitat other subspecies that have been studied in other regions. structure and small mammal communities in In the absence of its apparently competitive superior, the southeastern Virginia and northeastern North Carolina. Meadow Vole, it can reach densities as high as 14 per M. S. Thesis, Old Dominion University, Norfolk, hectare. Found mostly in damp habitats dominated by Virginia. 76 pp. grasses and sedges, its distribution is patchy but when present, it often is one of the 2-3 most numerous species Gaines, M S., R. K. Rose, & L. R. McClenaghan, Jr. taken in pitfall traps at a site. Often difficult to catch in 1977. The demography of Synaptomys cooperi in eastern live traps, its presence can be detected because of its Kansas. Canadian Journal of Zoology 55: 1584-1594. habit of depositing distinctive green feces in latrines along runways. Formerly believed to be restricted to Handley, C. O., Jr. 1979. Mammals of the Dismal the Great Dismal Swamp of southeastern Virginia, Swamp: a historical account. Pp. 297-357 In P. W. Kirk, the distribution of S. c. helaletes now extends westward Jr. (ed.), The Great Dismal Swamp, University Press of to include locations in western Sussex and Surry Virginia, Charlottesville. counties. Kenagy, G. J., & D. F. Hoyt. 1980. Reingestion of feces ACKNOWLEDGMENTS in rodents and its daily rhythmicity. Oecologia 44: 403- 409. I thank the U.S. Fish and Wildlife Service, Virginia Department of Game and Inland Fisheries, and several Krebs, C. J. 2013. Population Fluctuations in Rodents. environmental consulting firms for financial support of University of Chicago Press, Chicago, IL. 306 pp. field studies, former graduate students Roger Everton (who also read a draft of this paper), Thomas Padgett, Krupa, J. J., & K. E. Haskins. 1996. Invasion of the Jean Ferguson Stankavich, and John Walke, Meadow Vole {Microtus pennsylvanicus) in undergraduates David Harrelson, Rosiland Bowman, southeastern Kentucky and its possible impact on the and Darryl Thomas, and son John Rose for field Southern Bog Lemming {Synaptomys cooperi). assistance, Wayne Van Devender for the use of the American Midland Naturalist 135: 14-22. photograph, and the Old Dominion University Department of Biological Sciences for its support over Lewis, I. F., & E. C. Cocke. 1929. Pollen analysis of the years. Dismal Swamp peat. Journal of the Elisha Mitchell Scientific Society 45: 37-58. LITERATURE CITED Linzey, A. V. 1983. Synaptomys cooperi. Mammalian Beasley, L. E., & L. L. Getz. 1986. Comparison of Species 210: 1-5. demography of sympatric populations of Microtus ochrogaster and Synaptomys cooperi. Acta Theriologica Linzey, A. V. 1984. Patterns of coexistence in 31:385-400. Synaptomys cooperi and Microtus pennsylvanicus. Ecology 65: 382-393. Connor, P. F. 1959. The bog lemming Synaptomys cooperi in southern New Jersey. Publication of the Merriam, C. H. 1896. Revision of the lemmings of the Museum, Michigan State University, Biological Series genus Synaptomys, with descriptions of new species. 1: 165-248. Proceedings of the Biological Society of Washington 10: 55-64. ROSE: SOUTHERN BOG LEMMING 9 Rose, R. K. 1981. Synaptomys not extinct in the Dismal Rose, R. K., & L. J. Ford. 2012. Minor species as the Swamp. Journal of Mammalogy 62: 844-845. dominant rodents in an oldfield. American Midland Naturalist 168: 1-8. Rose, R. K. 1994. Instructions for building two live traps for small mammals. Virginia Journal of Science 45: 151- Rose, R. K., & M. S. Gaines. 1978. The reproductive 157. cycle of Microtus ochrogaster in eastern Kansas. Ecological Monographs 48: 21-42. Rose, R. K. 2005.The small mammals of Isle of Wight County, Virginia, as revealed by pitfall trapping. Rose, R. K., & J. F. Stankavich. 2008. Low-density Virginia Journal of Science 56: 83-92. rodent communities in eastern Virginia. Virginia Journal of Science 59: 169-184. Rose, R. K. 2006. Distribution and status of the Southern Bog Lemming, Synaptomys cooperi, in southeastern Shenko, A. N., W. B. Bien, J. R. Spotila, & H. W. Avery. Virginia. Virginia Journal of Science 57: 153-165. 2012. Effects of disturbance on small mammal community structure in the New Jersey Pinelands, USA. Rose, R. K. 2011. Range extension for the Dismal Integrative Zoology 7: 16-29. Swamp Southern Bog Lemming, Synaptomys cooperi helaletes, in eastern Virginia. Banisteria 38: 61-65. Wetzel, R. M. 1955. Speciation and dispersal of the Southern Bog Lemming, Synaptomys cooperi (Baird). Rose, R. K. 2016. The small mammals of southeastern Journal of Mammalogy 36: 1-20. Virginia as revealed by pitfall trapping. Banisteria 47: 9- 13.