Five-lined skink (Eumeces fasciatus) COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

Habitat of E. fasciatus varies throughout its distribution and includes rocky outcrops, sand dunes, riparian forests, open deciduous forests, and cut-over woodlots (Fitch, 1954; Seburn, 1990). The species is found in a variety of habitat conditions with different climates and plant associations, although the species is limited to climates of relatively higher humidity and generally occurs in early successional habitats. Within forest habitats, the species is most abundant in well-drained, open, rocky areas. In northeastern Kansas, individuals prefer woods with low to moderate canopy cover, which allows for sunlight to reach the forest floor, where individuals are usually found under rocks or decaying logs. Towards the southern extent of its range, the species is found in more heavily wooded habitats, whereas in northerly parts of its range, the species is found in increasingly open habitats (Fitch, 1954).

Suitable microhabitats are of vital importance to E. fasciatus, as individuals spend most of their time in refuges under cover shelter, while making short foraging trips from a heavily used core area (Fitch and von Achen, 1977). Individuals are prone to desiccation stress (Fitch, 1954) and extreme temperatures, thereby making shelter an essential microhabitat element (Hecnar and M’Closkey, 1998). Furthermore, shelter with suitable thermal properties allows individuals to maintain a body temperature close to their preferred optimal temperature, while providing them with concealment from predators (Quirt et al., in press).

The particular shelter element (e.g. cover rock, wood debris, standing snags, tree cavities) used by individuals varies across the range of the species and is dependent on habitat type and available shelter elements (B. Howes, personal observation [pers. obs.]). The particular shelter element used also varies throughout the year as individuals adjust microsite selection based on thermoregulatory, foraging, predator concealment, nesting and hibernation needs (Hecnar, 1991; Seburn, 1993). Throughout the range, individuals also use artificial cover elements including scrap tin and wood piles, stone and wood fences, boardwalks, picnic shelters, and buildings such as park Visitor Centres and maintenance yards (B. Howes, pers. obs.).

In Ontario, individuals of E. fasciatus in both Great Lakes/St. Lawrence and Carolinian populations show a strong association with particular microhabitat elements (e.g. Hecnar and M’Closkey, 1998; Howes and Lougheed, 2004). Based on such specific microhabitat requirements, the species could be classified as a habitat specialist in Ontario. It should be noted that habitat research performed in northeastern Kansas (Fitch, 1954), southwestern Ontario (Seburn, 1993; Hecnar, 1994) and on the Shield in Ontario (Howes and Lougheed, 2004; Quirt et al., 2006) populations are based on diurnal surveys throughout the active season. Little is known about nocturnal microhabitat use or hibernation microsite selection.

Great Lakes/St. Lawrence populations

Great Lakes/St. Lawrence populations are distributed along the southern edge of the Canadian Shield on rocky outcrops embedded within a matrix of coniferous and deciduous forest. Potential habitat is patchy due to the natural fragmentation and patchiness of open rock outcrops within the region. Exposed rock outcrops are covered with loose rock of variable sizes that provide cover to individuals of E. fasciatus. Nearly all observations of E. fasciatus on the Shield indicate an association with rocky microhabitat (Oldham and Weller, 2000; Howes and Lougheed, 2004). Skinks in these populations use loose rock on open rock faces as cover elements and are rarely observed outside of this cover element (Howes and Lougheed, 2004; B. Howes, pers. obs.).

The best predictor of diurnal presence of skinks in seven Great Lakes/ St. Lawrence populations was the proportion of available cover rock at a microsite (Howes and Lougheed, 2004). More intensive research within two of these populations revealed that individuals of E. fasciatus exhibited a preference for longer than average available cover rocks located in exposed outcrop areas with few trees. Cover rocks used by skinks were on average 55.2 cm in length whereas cover rocks that were not used by skinks were on average 33.5 cm in length. Compared to other microsites available in the Shield habitat, rocks lying on a bedrock substrate provided the best opportunities for skinks to achieve their preferred body temperatures (determined to be 28ºC-36ºC; Fitch, 1954) (Quirt et al., 2006).  The diurnal mean absolute deviation from preferred body temperature range was 1.99ºC under cover rocks that were occupied by skinks, and 4.33ºC under cover rocks that were unoccupied by skinks. Other cover elements available in this habitat (logs on bedrock, logs in forest, rocks in forest) seldom reached the species’ preferred body temperature range (Quirt et al., 2006).

Carolinian populations

Carolinian populations are found on or near the shores of Lakes Erie, St. Clair, and Huron in Carolinian forest. Remaining potential habitat is extremely patchy due to anthropogenic fragmentation (agricultural lands and urban areas). Individuals are generally found under woody debris in clearings within stabilized sand dunes, open forested areas and wetland areas (Seburn, 1993; Hecnar, 1994). The population of E. fasciatus at Point Pelee National Park (PPNP) is the longest-studied population in the species’ Canadian range. Research performed in PPNP has shown that individuals in this population have a strong association with woody debris as a cover element (Seburn, 1993; Hecnar, 1994; Hecnar and M’Closkey, 1998). Almost all cover material used by skinks within PPNP is woody debris (Seburn, 1990). The importance of woody debris has also been observed for the population of Rondeau Provincial Park. Numbers of skinks observed here seemed to increase following the 1998 wind storm that resulted in more fallen debris in the park (S. Dobbyn, personal communications [pers. comm.]). Other materials used by southwestern Ontario skinks include artificial materials such as building materials, utility poles (Seburn, 1990a) and wooden boardwalks (Hecnar and M’Closkey, 1998).

Individuals of E. fasciatus in PPNP prefer large (logs that are >17 cm diameter and boards that are > 1,700 cm² in area), moderately decayed woody debris over small woody debris possibly because a larger surface area may offer more suitable substrate moisture levels (Hecnar, 1991; Seburn, 1993). Along with the surface area of a cover element, Seburn (1993) also showed that thickness is an important microhabitat feature. Cover elements that were <10 cm in thickness were preferred by individuals, possibly because a thinner cover element allows for an individual to reach a more optimal temperature more quickly than a thicker cover element (Seburn, 1993). The temperature under woody debris cover elements occupied by skinks ranged from 21.6-24.9ºC (Hecnar, 1991). Microsites selected by nesting females in PPNP were a subset of microsites selected by all individuals throughout the season (Seburn, 1993). Nest microsites tended to be under logs rather than artificial boards, and soil moisture in these microsites was higher than in other selected microsites (16.6-67.3% and 2.2-24.6% respectively) or than the ambient environment (Hecnar, 1994).

Habitat trends

Undoubtedly, E. fasciatus has incurred range-wide habitat loss and fragmentation. However, because the species inhabits early successional habitats and because it will use a variety of anthropogenic debris and structures as cover material, it can exist in areas that have been slightly modified by humans throughout much of its range, especially in the southern portion of its range (B. Howes, pers. obs.).

Both series of populations of E. fasciatus in Ontario have incurred habitat loss and fragmentation over the last century due to increased human settlement and disturbance. The Great Lakes/St. Lawrence populations exist in a region that has less human disturbance relative to other regions in southern Ontario, but increased cottage development and outdoor recreation are increasing threats to skink habitat in the Shield region. Carolinian populations have incurred considerable threats from human disturbance and have experienced considerable declines in habitat and number of populations based on observations from the OHS (Oldham and Weller, 2000; see Table 1).

Great Lakes/St. Lawrencepopulations

The rate of habitat change in Great Lakes/St. Lawrence populations appears to be relatively low. Loss of open rock outcrop habitat due to successional processes is relatively slow compared to natural succession in Carolinian populations (Seburn and Seburn, 1998), therefore the natural rate of change in Shield habitat is a relatively low threat. Because the region is characterized by thin soil overlaying rock substrate, conversion of natural habitat into agricultural land has been minimal and is unlikely to become a threat. Finally, human settlement and development within the region is primarily limited to rural areas and cottages. Such development may become a threat to some populations if encroachment of natural areas by cottage development continues.

Carolinian populations

The rate of habitat change in Carolinian populations has historically been much more severe than in Great Lakes/St. Lawrence populations, and undoubtedly it is this rate of habitat change (primarily anthropogenic) that has contributed to the decline in populations within this region over the last few decades (see Tables 1 and table2). The Carolinian forest ecosystem in southwestern Ontariois a particularly biologically diverse region, but agriculture and urban development have drastically altered the region and these pressures continue to threaten remaining habitat. Only 10% of original Carolinian forest in southwestern Ontario remains, and it harbours approximately 40% of Canada’s species at risk (CWS, 2006).

The rate of natural succession of habitat is a concern in Carolinian populations. It has been suggested that in some areas, fire suppression and other management activities may limit the amount of open habitat available for use by E. fasciatus. Prescribed burning is being used in some Carolinian populations (e.g. Rondeau Provincial Park and Pinery Provincial Park – S. Dobbyn, pers. comm.). Habitat in some Carolinian populations is also altered by continuous deposition and erosion of sand within the stabilized dunes of Lake Erie (East, 1976 in Hecnar, 1994).

Habitat protection/ownership

Great Lakes/St. Lawrencepopulations

A summary of extant populations in Ontario that occur in Federal Land, Provincial Land, Conservation Areas and Areas of Natural and Scientific Interest (with varying degrees of protection) is provided in Table 3. This summary is based on OHS records. As the number of Great Lakes/St. Lawrence populations located in Provincial Land is likely underestimated by OHS records (M. Oldham, pers. comm.), it should be noted that the number of Great Lakes/St. Lawrence populations located in Provincial Land may also be underestimated in Table 3.

Table 3. Summary of extant (recorded or confirmed since 1995) populations of Eumeces fasciatus in Ontario that exist in Federal Land (National Parks or Indian reserves), Provincial Land (Provincial Parks, Provincial Park Reserves, Nature Reserves), a Conservation Area (CA), or an ANSI (Area of Natural and Scientific Interest) based on the Ontario Herpetofaunal Summary (Oldham and Weller, 2000). Populations are classified according to region (Great Lakes/St. Lawrence vs. Carolinian populations) and county. The total number of populations within each selected land type and within each county is listed.
County Observed 1995- Present Federal Land Provincial Land CA ANSI Total % Extant Populations in Classified Land Types
Great Lakes/St. Lawrence populations:Frontenac
9
0
1
0
0
1
11%
Great Lakes/St. Lawrence populations: Grey
1
0
1
0
0
1
100%
Great Lakes/St. Lawrence populations: Haliburton
2
0
1
0
0
1
50%
Great Lakes/St. Lawrence populations: Hastings
4
0
0
1
0
1
25%
Great Lakes/St. Lawrence populations: Lanark
2
0
0
0
0
0
0%
Great Lakes/St. Lawrence populations: Leeds
1
1
0
0
0
1
100%
Great Lakes/St. Lawrence populations: Lennox & Addington
7
0
2
1
0
3
43%
Great Lakes/St. Lawrence populations: Muskoka
19
5
3
0
0
8
42%
Great Lakes/St. Lawrence populations: Parry Sound
16
0
8
0
0
8
50%
Great Lakes/St. Lawrence populations: Peterborough
15
0
2
0
0
2
13%
Great Lakes/St. Lawrence populations: Simcoe
4
0
1
0
0
1
25%
Great Lakes/St. Lawrence populations: Victoria
4
0
1
1
0
2
50%
Total Great Lakes/St. Lawrence populations
84
6
20
3
0
29
31%
Carolinian populations: Chatham-Kent
1
0
1
0
0
1
100%
Carolinian populations: Essex
2
1
0
0
1
2
100%
Carolinian populations: Lambton
2
1
1
0
0
2
100%
Total Carolinian populations
5
2
2
0
1
5
100%

Approximately 30% of extant (reported or confirmed since 1995) Great Lakes/ St. Lawrence populations are located in Federal Land, Provincial Land, Conservation Areas or Areas of Natural and Scientific Interest (Table 3). Extant populations occur on the following Federal lands: Georgian Bay Islands National Park (contains four recorded island populations), St. Lawrence Islands National Park, and Moose Point 79 Indian Reserve. A population was also reported on Magnetawan 1 Indian Reserve, although no records of this population have been made since 1988 (Oldham and Weller, 2000). Other Indian Reserves within the species’ Shield distribution that have suitable skink habitat but have not been listed in the OHS (Oldham and Weller, 2000) include Chippewa Island, Christian Island 30A, Curve Lake First Nation 35, Henvey Inlet 2, Islands of the Trent Waters 36A, Mnjikaning, Naiscoutaing 17A, Parry Island First Nation, Shawanaga 17, Shawanaga 17B, and Wahta Mohawk Territory (Committee on the Status of Endangered Wildlife in Canada, 2006). Extant Great Lakes/ St. Lawrence populations also occur in many Provincial Lands including Provincial Parks, Conservation Reserves, and Nature Reserves.

Carolinian populations

All five extant (reported or confirmed since 1995) Carolinian populations are located within Federal Land, Provincial Land, Conservation Areas or Areas of Natural and Scientific Interest (Table 3). Point Pelee National Park and Walpole Island occur on Federal Land. The three remaining extant Carolinian populations occur on Provincial Land (Rondeau Provincial Park and Pinery Provincial Park), or in an Area of Natural and Scientific Interest (ANSI – Oxley Poison Sumac Swamp).

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