Southern flying squirrel (Glaucomys volans) COSEWIC assessment and status report: chapter 9

Population Sizes and Trends: Great Lakes Population

Search Effort

Very little systematic trapping for southern flying squirrels has occurred in the Great Lakes Plains Population. Population data are available for Point Pelee National Park (Bednarczuk and Stephens 2004; Bednarczuk 2003; Adams 1997) and Algonquin Provincial Park (G. Holloway unpubl. data). From 2002 through 2004, J. Bowman, P.J. Wilson, G.L. Holloway and J.R. Malcolm (unpubl. data.) completed 42 971 trap nights at 26 different sites throughout south and central Ontario (see Table 5) capturing 500 southern flying squirrel individuals 748 times. Their annual catch per unit effort was 1.36 captures per 100 trap nights in 2002 (8 542 trap nights), 3.57 captures per 100 trap nights in 2003 (16 597 trap nights), and 0.22 captures per 100 trap nights in 2004 (17 832 trap nights). Catch per unit effort data derived from other locations in Ontario are reported in Table 6.

Table 5: Site Locations of Southern Flying Squirrel Trapping Effort in Ontario, 2002–2004
Site 2002 2003 2004 New
Record
G. volans
detected
Trap Nights G. volans
detected
Trap Nights G. volans
detected
Trap Nights
Clear Creek Forest     yes 1 500 yes 120  
Krug Forest (FON Tract)     no 128     No
Sites in Grey County     no <50      
Sites in Bruce County     no 130      
Ganaraska Forest     no 266 yes 400 Yes
Henderson Line Woodlot (Peterborough)         yes 75 Yes
Keene Road Woodlot (Peterborough)         no 75 No
Mark S. Burnham Provincial Park         no 75 No
Oliver Property (Trent Research Station, Pigeon Lake) yes 68 yes 87 yes 84  
Kawartha Highlands Signature Site yes 183 yes 120 yes 60 Yes
Leslie M. Frost Centre yes 154 yes 440 yes 400 Yes
Crown land adjacent to Killbear Provincial Park     yes 30     Yes
Haliburton Forest & Wildlife Reserve         yes 2 685 yes
Crown land adjacent to Killbear Provincial Park     yes 30     yes
Algonquin Provincial Park - Hwy 60 yes 5 043 yes 9 499 no 11 295 yes
Algonquin Provincial Park - Achray yes 3 094 yes 2 286 no 900 yes
Algonquin Provincial Park - Kiosk     yes 930 no 128 yes
Killarney Provincial Park     yes 367 no 180 yes
Nipissing Crown Game Preserve     no 140      
North of Mattawa (Olrig and Antoine Townships)     yes 315 no 400 yes
Emerald Lake (Afton Township)     yes 345     yes
Highway 11 corridor between Temagami North and Latchford         no 420  

Source for all data: J. Bowman, P.J. Wilson, G.L. Holloway and J.R. Malcolm (unpubl. data.), except Clear Creek Forest: Pasma and Dobbyn (2003).

 

Table 6: Live-trapping Data from Various Southern Flying Squirrel Field Projects in Ontario, 1993 to 2003 (* denotes catch per unit effort corrected for closed but empty traps or non-target species)
Location Year n
(indiv)
Catch per
Unit Effort
Source
Point Pelee National Park 2001 155 44%* Bednarczuk 2003
2003 68 22%* Bednarzcuk and Stephens 2004
Clear Creek Forest 2003 38 6.0%* Pasma and Dobbyn 2003
Norfolk Township 1993/94 114 0.84% Adams 1995
2000 396 45.8% Bednarczuk 2003
Hamilton 1999 – 2001 200+ 20-50% Bednarczuk and Judge 2002
Minden 2001 21 21.6% Bednarczuk 2003
Trent University Research Station 2001 25 5% L. Bridges pers. comm. 2004
2002 4 6% P. Wilson pers. comm. 2004
OMNR provincial study (Table 5) 2002 8 542 TN* 1.36% Bowman et al. unpubl. data
2003 16 597 TN* 3.57%
2004 17 832 TN* 0.22%

* denotes number of Trap Nights


Abundance

There is no abundance estimate for the Great Lakes Plains Population. Multiplying even a conservative density estimate by the area of Extent of Occurrence would provide a vast over-estimate of population size because the Area of Occupancy (unknown) is a small fraction of the Extent of Occurrence.

Estimates of population size for southern flying squirrels are constrained by low capture rates and unequal capture of individuals. G. volans also exhibits wide annual variation, rendering any point-in-time estimate unreliable. Published densities vary widely (Table 7). Raised trap height can increase trapping success (Risch and Brady 1996), but catch per unit effort is usually quite low (Table 6).

The total number of individuals of all ages in the Great Lakes Plains population may number in the several thousands to tens of thousands, the majority of which are mature individuals capable of reproducing. Roughly half of the marked population at Point Pelee National Park was composed of mature individuals in 2001, and 75% of captured individuals in 2003 were mature (Bednarczuk and Stephens, 2004). During trapping in Hamilton in 2001, 2.5 times more adults than juveniles were captured (Bednarczuk and Judge 2002).

 

Table 7: Southern Flying Squirrel Density Estimates
Location Density (per ha) Forest type Source
Point Pelee National Park, Ontario 1.7 – 2.3 (2001)
hackberry, maple, oak Bednarczuk and Stephens, 2004
0.3 – 0.4 (2003)
Algonquin Prov. Park, Ontario 2.9 (2003) beech – maple G. Holloway unpubl. data
2.6 (2003) sugar maple
0.6 (2003) mixed maple - conifer
no captures in 2004  
Nova Scotia 0.9 – 8.4* mixedwood Lavers 2004
Michigan 2.82 oak – hickory Jordan 1948
5   Baker 1983 (in Stabb 1988)
Maryland 6.2 hardwood - conifer Gilmore and Gates 1985
Virginia 34.0 – 38.0 hardwood – pine Sawyer and Rose 1985
3.7 – 13.8 oak – hickory - beech Sonenshine et al. 1979
Arkansas 0.2 – 0.9 pine – hardwood Taulman 1999
Alabama 1.8 – 3.5 pine – oak Hatten 1992

* Lavers (pers comm 2004) advised caution when using these population data as they are based on few captures.


Fluctuations and Trends

There are few data on population fluctuations for the Great Lakes Plains population, due to a lack of long-term monitoring studies and no historical data. However, results from northern and central Ontario and Point Pelee National Park suggest that southern flying squirrels undergo wide population fluctuations throughout the Great Lakes range.

Given widespread habitat loss throughout southern Ontario (see Habitat Trends: Great Lakes), a decline from historical levels has probably occurred. Observed range extensions in central Ontario appear subject to fluctuation and may not offset declines in the southern part of G. volans’ Great Lakes Plains population range.


Rescue Effect

There is limited possible rescue effect for the Great Lakes Plains population. Immigration to Ontario is restricted by the Great Lakes and their associated rivers. Flying squirrels are poor swimmers because the patagium restricts leg movement. They therefore can cross water bodies no wider than “one glide”; maximum 50 m.

The only land border between the United States and Canada is in southwestern Québec. There is little known about southern flying squirrel distribution in this area of Québec or adjacent states New York, Vermont and New Hampshire.

 

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