Five-lined skink (Eumeces fasciatus) COSEWIC assessment and status report: chapter 8
Limiting Factors and Threats
Habitat alteration
Like most species at risk, E. fasciatus in Ontario is threatened by habitat loss, fragmentation, and degradation caused by increased human settlement and recreation. This is most evident in southwestern Ontario where skink populations have undergone considerable decline, largely due to increased urban settlement and agriculture which have proliferated in many places where skinks occurred 2-3 decades ago (Hecnar personal communication [pers. comm.]). Habitat alteration is a less serious threat in the Shield region, and the skinks are much more widespread. Nevertheless, loss and degradation of habitat is still a real threat in the Shield region. For instance, one Great Lakes/St. Lawrence population appears to have suffered a decline in individuals because of habitat degradation caused by all terrain vehicles (ATV) and dirt bike trails (B. Howes, personal observation [pers. obs.]). The site (located on Crown Land underneath a large power line) was an excellent example of reptile habitat in the southern Shield area, with large rock outcroppings in a matrix of low-lying vegetation and mixed deciduous and coniferous forest. Within four years, most of the vegetation surrounding the outcrops has been turned into barren sand, and cover rocks on outcrops have been removed to facilitate “trailing” on bald rock (B. Howes, pers. obs.). Similar local losses of populations have been observed at other locations on the Shield (R. Brooks, pers. comm.).
Microhabitat alteration
Hecnar and M’Closkey (1998) showed that loss of microhabitat elements in a Carolinian population (Point Pelee National Park [PPNP]) resulted in a three-fold to five-fold decline in skink abundance between 1990-1995. Loss of microhabitat is clearly the most severe form of microhabitat alteration, but repeated disturbance can also negatively impact a population’s abundance. Significantly fewer skinks were found in areas that had high levels of human disturbance relative to areas of low human disturbance (Hecnar and M’Closkey, 1998; see Fluctuations and Trends section). A single alteration to a microhabitat element could result in a decline of its quality. For instance, a cover rock or log that is flipped and not replaced exactly to its original position may alter the particular microclimate conditions it provides. Even when replaced to its original position, substrate elements (e.g. soil, lichen) may be disturbed.
Even Carolinian populations within protected areas are still at risk of microhabitat alteration, as woody debris may be cleared from beaches for aesthetic reasons or may be removed for firewood (Hecnar and M’Closkey, 1998). Although microhabitat requirements appear to be equally important in Great Lakes/St. Lawrence populations (Howes and Lougheed, 2004; Quirt et al., 2006), the threat of microhabitat alteration in this series of populations appears to be lower. However, evidence of disturbance in the form of recently flipped rocks has been observed, whether by humans or black bears (K. Prior, pers. comm.; B. Howes, pers. obs., R. Brooks, pers. comm.). Furthermore, removal of rock from Shield habitat for urban landscaping has also been observed (e.g. Manitoulin Island, Kawartha Lakes (M. Oldham, pers. comm.).
Illegal collecting
Illegal collecting of the species in Ontario was first noticed in a Carolinian population (PPNP) in 1989. Four of eight monitored clutches disappeared, and their disappearance coincided with the movement or destruction of the nesting microsite that consisted of woody debris (Seburn and Seburn, 1998). In 1990, large-scale disturbances to microsites occurred and these disturbances corresponded with the disappearance of gravid females or clutches (Hecnar and M’Closkey, unpublished data in Seburn and Seburn, 1998). In 1989, prior to these microsite disturbances, hatchlings represented 45% of all individuals sampled (Seburn, 1990). Following the disturbances (from 1990-1995), hatchlings represented only 1% to 21% of individuals captured (Hecnar and M’Closkey, 1998).
Hecnar and M’Closkey (1998) found that four out of four local pet stores interviewed were willing to fill orders for five-lined skinks, and one employee actually suggested collecting skinks directly from PPNP. The potential threat of illegal collecting is enhanced by the social behaviour displayed by gravid and brooding females (Hecnar and M’Closkey, 1998). It is possible that illegal collecting is also occurring in Great Lakes/ St. Lawrence populations, but this has yet to be documented.
Depredation by raccoons
Recent observations in one Carolinian population (PPNP) suggest that considerable predation of skinks by raccoons is occurring (Hecnar and Hecnar, 2005). This notion is supported by research that indicates the raccoon density within this park is four-fold higher than the average raccoon density in rural Ontario (Phillips and Murray, 2005, in Hecnar and Hecnar, 2005).
Road mortality
Further research performed in PPNP revealed that road mortality of skinks is occurring. A recent road mortality study indicated that 14 skinks were killed on the park road in 11 days (V. McKay, pers. comm. in Hecnar and Hecnar, 2005). While road mortality has long been identified as a threat to amphibians and reptiles in Ontario (e.g. Ashley and Robinson, 1996), this threat has perhaps been underestimated for skinks in southwestern Ontario. The threat of road mortality to five-lined skinks has been identified elsewhere in the species’ range (Florida – Aresco, 2003), and evidence of road mortality has also been observed elsewhere in the species’ range (Illinois – B. Howes, pers. obs.).
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