Southern flying squirrel (Glaucomys volans) COSEWIC assessment and status report: chapter 6

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Distribution

• Global Range
• Canadian Range
• Great Lakes Plains Population Range
• Atlantic (Nova Scotia) Population Range

Global Range

G. volans occurs from central Minnesota to the Gulf of Mexico (Figure 1). The western limit of the range is approximated by the prairie tree line, including eastern Nebraska, Kansas, Oklahoma and Texas (Stabb 1988). Isolated populations occur in Nova Scotia (Figure 1), Mexico and Central America as far south as Honduras (Dolan and Carter 1977; Diersing 1980).

Figure 1: The Global Distribution of Glaucomys volans

Map developed from Bowman et al. (unpubl. data), Lavers (2004), NatureServe (2004), Dobbyn (1994) and Dolan and Carter (1977). Question marks indicate uncertain range limits in Canada.

There is a single record of a southern flying squirrel from Eastport, Maine, on the coast near the New Brunswick border (Cameron 1976; Godin 1977 in Stabb 1988). Habitat modelling for southern flying squirrels in Maine (Krohn et al. 2001) suggests they may occur only along the state’s coast. However, the species is rarely documented there. Cameron (1976) reported only six records of southern flying squirrels for Maine, including the Eastport record. O’Connell et al. (2001) captured only northern flying squirrels on Mt. Desert Island (Acadia (US) National Park), despite historical records of southern flying squirrels being present there.

Canadian Range

Recent surveys suggest the northern limit of the Great Lakes Plains population occurs as far north as Temagami and Killarney, Ontario (J. Bowman pers. comm. 2004). The Atlantic population is at least 500 km by land from G. volans in Maine (Lavers 2004).

The southern flying squirrel is not known from New Brunswick. Studies on northern flying squirrels (e.g. Vernes 2004; Gerrow 1996) in Acadia National Park found no southern flying squirrels despite efforts to do so (D. Sabine pers. comm. 2004; M. Smith pers. comm. 2004). The range map currently available at NatureServe (2004) incorrectly shows G. volans occurring in southern New Brunswick and throughout mainland Nova Scotia.

Great Lakes Plains Population Range

Southern flying squirrels range along the northern shore of Lakes Erie and Ontario eastward into southwestern Québec. Northward, the species is found throughout much of central Ontario, though notably the species is absent or largely absent from that area north and west of Guelph and Orangeville, including the Dundalk Uplands (Ontario Island) and the Niagara Escarpment including the Bruce Peninsula and Manitoulin Island (J. Bowman. pers. comm. 2004; Figure 2).

Across central Ontario, G. volans occurs north through Haliburton Co., Muskoka Dist., Renfrew Co., Nipissing and Parry Sound districts, north to eastern Sudbury Dist. (Killarney Provincial Park) and northern Nipissing Dist. (Temagami).

The Great Lakes Plains population appears well connected in the contiguous forests of central Ontario (J. Bowman pers. comm. 2004). There is uncertainty whether there is a gap in southern flying squirrel occurrence between, approximately, Toronto and Hamilton (J. Bowman pers. comm. 2004). If this gap occurs, the Great Lakes Plains population may be effectively split in two between southwestern Ontario and eastern / central Ontario. In southwestern Ontario, southern flying squirrels persist mainly in isolated sub-populations; only in Norfolk County is there good connectivity between large patches of suitable habitat.

Figure 2: Range of Great Lakes Southern Flying Squirrel Population

Black circles indicate sites with documented southern flying squirrel presence by J. Bowman (unpubl. data); G. Holloway (unpubl. data); Bednarczuk 2003; Pasma and Dobbyn 2003; Bednarczuk and Judge, 2002; Adams 1995; St. Lawrence Islands National Park 1985. White circles indicate sites sampled by J. Bowman et al. (unpubl. data) during 2002-2004 and Aurora District MNR 2004 where southern flying squirrels were not detected. Black squares are selected historical records from Dobbyn (1994) to document estimated extent of occurrence. The Québec distribution is after Québec MRNFP (2004). The Haliburton Forest and Wildlife Reserve was the northernmost record of southern flying squirrels in central Ontario during 2004 field work.

There has been no systematic effort to search for this species in Québec. In the Outaouais Region, their confirmed distribution is between Pointe-aux-Chènes (east) and Fort-Coulonge (West); the northern-most report is at Sandall Lake (46°08' N; 76°28' W) west of the municipality of Lac Cayamant, 50 km north of Gatineau (D. St.-Hilaire pers. comm. 2004). G. volans is likely present elsewhere in the southern part of the province where suitable habitat exists including north of the Ottawa River and in the Eastern Townships as far east as Sherbrooke or Mont-Mégantic (Table 3). The species’ presence in northern New York, Vermont and New Hampshire is also uncertain (J. Litvaitis pers. comm. 2004). In Maine, sightings and suitable habitat are restricted to coastal regions.

The Extent of Occurrence of the Great Lakes Plains population is estimated at approximately 160 000 km². The Area of Occupancy is unknown but likely to be significantly lower.

Number (in parentheses) following protected area name correlates to location on Figure 4.

The northern limit of the Great Lakes Plains Population range appears to fluctuate widely. In 2003, southern flying squirrels were found as far north as Temagami, Ontario. In 2004, with similar trapping effort at the same locations, they were undetected north of the Haliburton Forest and Wildlife Reserve (north of Haliburton, ON) and nearby Leslie Frost Centre (south of Dorset, ON), over 200 km south of the 2003 northern limit (G. Holloway pers. comm. 2004; J. Bowman pers. comm. 2004). The Leslie Frost Centre was the previously accepted range limit (Stabb 1988). Bowman et al. (unpubl. data) carried out considerable search effort in 2004 (13 259 trap nights) north of this latitude with no captures.

These data reflect a substantial population crash in 2004, especially at northern part of the range. Bowman et al. (pers. comm. 2004) attribute the decline to an energetic bottleneck during winter 2004 brought about by a combination of a cold winter and a documented failed mast crop in autumn 2003. Southern flying squirrels had little food available to hoard for winter 2004 and were likely unable to persist through the cold months. Spring breeding would have failed as well, but this was probably unimportant, since even adults were not detected during 2004 surveys.

Atlantic (Nova Scotia) Population Range

Southern flying squirrels were not known from Nova Scotia prior to 1971 (Wood and Tessier 1974). Their isolation from other southern flying squirrel populations (Figure 1) precludes the possibility of recent migration explaining their presence in Nova Scotia. Flying squirrels’ nocturnal habits allow their presence to be often unnoticed and traps set on the ground or at elevations <1.0 m have very low capture rates for southern flying squirrels (Risch and Brady 1996). Additionally, several other vertebrates were documented only recently from Nova Scotia, including Microtus chrotorrhinus, Lasionycteris noctivagans, Pipistrellus subflavus, Sorex dispar, Sorex gaspensis. Most of these over-looked mammals are nocturnal, highly cryptic, geographically isolated and/or require specialized inventory methods to determine presence or absence (M. Elderkin pers. comm. 2004).

G. volans occurs in southern Nova Scotia in an area roughly bounded by the South Mountains in the north, the Gaspereau Valley (Kentville) to the west, the New Ross area in north-east Lunenburg County to the south and Kejimkujik National Park in the west.

Prior to 2001, southern flying squirrels were documented from only seven locations in Nova Scotia: five in Kejimkujik National Park and two near Kentville in Kings County (Lavers 2004). G. volans in Nova Scotia was previously considered to be two isolated “populations” centred on Kejimkujik National Park and Kentville (Stabb 1988). Lavers (2004) collected records (live or specimen) from 32 new locations in southwestern Nova Scotia representing 60 individuals suggesting a single continuous population (Figure 3). Southern flying squirrels may occur further south (toward Yarmouth and Shelburne) of the current known range limit, including the Tobeatic Wilderness Area. The population’s Extent of Occurrence is estimated at 6500 km², based on an analysis of point locations of sighting records.

Figure 3: Range of Atlantic Population of Southern Flying Squirrel

Black circles indicate record locations.

Genetic evidence (Petersen 2004, see Genetic Description) supports southern flying squirrels being native to Nova Scotia and not recently introduced by humans. Previous records documenting only northern flying squirrels in the province (e.g. Smith 1940; Banfield 1974)