Five-lined skink (Eumeces fasciatus) COSEWIC assessment and status report: chapter 6

Biology

The biology of E. fasciatus has been studied by several authors throughout the species’ range. Henry Fitch reported on the life history of the species (including annual cycle of reproduction and growth, food habits, movements, and recruitment) on a population in northeastern Kansas (Fitch, 1954). Laurie Vitt and William Cooper have produced numerous accounts of the species biology that describe reproductive biology, odour detection, and tail autotomy (e.g. Cooper and Vitt, 1985; Vitt and Cooper, 1985; Vitt and Cooper, 1986a; Vitt and Cooper, 1986b; Cooper and Vitt, 1987; Cooper and Vitt, 1988). Carolyn Seburn, Stephen Hecnar and Robert M’Closkey have performed research in one Carolinian population that illuminates various aspects of the species’ biology including microhabitat and nest site selection, movement patterns and population trends (Seburn, 1993; Hecnar, 1994; Hecnar and M’Closkey, 1998; Hecnar et al., 2002). Habitat research has been performed in Great Lakes/St. Lawrence populations (Howes and Lougheed, 2004; Quirt et al., 2006), and fine-scale genetic research has also been performed in Great Lakes/St. Lawrence populations (Wick, 2004; Wick and Bogart, unpublished data; Howes and Lougheed, unpublished data). The majority of the information on species’ biology discussed below comes from these sources.

Life cycle and reproduction

Reproduction

Age of sexual maturity is 21 months based on research performed in Kansas (Fitch, 1954) and South Carolina (Vitt and Cooper, 1986a), although size at sexual maturity differed between the two sites (60 mm and 52 mm respectively; Fitch, 1954, Vitt and Cooper, 1986a). Fitch (1954) suggested that sexual maturity varies across the species’ range so that some individuals in southern parts of the range may achieve breeding size in their first summer while some individuals in northern parts may not achieve breeding size until their third summer. However, some individuals in a Carolinian population achieved minimum breeding size in their first summer, although it is unlikely that these individuals successfully reproduced until their second summer (Seburn and Seburn, 1998). This suggests that the average age at sexual maturity is relatively similar throughout the range of E. fasciatus.

In sexually mature males, breeding colours develop following emergence from hibernation and peak during the breeding season that lasts approximately two weeks (Fitch, 1954). These breeding colours can be induced during other parts of the year with testosterone treatments (Edgren 1959), and head colouration likely evolved as a consequence of sexual selection (Cooper and Vitt, 1988). Males use this head colouration along with chemical stimuli to identify the sex of conspecifics (Vitt and Cooper, 1986a; Cooper and Vitt, 1987; Cooper and Vitt, 1988). Although individuals do not defend territories, aggression between males during the breeding season has commonly been observed and reported (Fitch, 1954; Cooper and Vitt, 1987; Seburn, 1993). Vitt and Cooper (1985) showed that in E. laticeps, adult males with larger body size and larger relative head size were more likely to win intrasexual aggressive encounters and were more likely to be observed with females during breeding season (Vitt and Cooper, 1985).

In the spring, males spend the greater part of their time searching for females by visual and chemical stimuli and track females using a scent trail (Fitch, 1954). A variety of cloacal glands and other structures in both sexes produce pheromones (Madison, 1977; Simon, 1983), and although both males and females can detect conspecific odours, females show lower responsiveness to these chemical stimuli than males (Duvall et al., 1980).

When a male approaches a female, he attempts to bite any part of her body or tail. Once he restrains her with his bite, he adjusts his grip so that his jaw is grasping the loose skin on the dorsal side of the female’s neck. The male then thrusts his tail beneath the female’s tail, establishes cloacal contact and copulation begins. Immediately following copulation, the female will struggle to be free from the male’s grasp. When the male releases his grip, the female moves away, often pressing her cloacal region against the ground (Fitch, 1954). The male may follow behind her for a short time, and he may even remain with her for a short period of time to guard her against other males (Vitt and Cooper, 1985). Based on genetic data, multiple paternity was evident in 4/9 nests examined in a Great Lakes/ St. Lawrence population (Wick, 2004).

The ova of sexually mature females begin developing following emergence from hibernation and reach their full size after copulation has occurred (Fitch, 1954). As eggs develop within the female, she becomes less active. She will eventually stop foraging (Cooper et al., 1990), and locate a suitable microsite in which to excavate a nest chamber (Fitch, 1954; Hecnar, 1994). In a Carolinian population, three females were observed to move 23-68 m prior to oviposition, and then return to their pre-oviposition site following hatching of their eggs (Seburn, 1993).

Females of E. fasciatus use a wide range of nesting sites relative to other North American lizards (Fitch, 1954), although they are all generally located within or beneath a cover element. Nest sites include beneath or within decaying logs, trees or stumps (Fitch, 1954; Vitt and Cooper, 1986a; Seburn, 1990; Hecnar, 1991), and beneath rocks (Fitch, 1954; Wick, 2004). In Great Lakes/St. Lawrence populations, nest sites are found beneath cover rock in small depressions of soil over rock substrate. Based on 16 located nest sites in one Great Lakes/St. Lawrence population, the average dimension of nest site cover rock was 39.3±3.1 cm in length, 33.3±4.5 cm in width, and 15.6 ± 1.0 cm in thickness (Wick, 2004). In Carolinian populations, nest sites are commonly found on sandy substrate beneath woody debris (Seburn, 1993; Hecnar, 1994) and are a subset of all microsites used by individuals throughout the year (Seburn, 1993; Hecnar, 1994).

Females were highly aggregated throughout the summer in a Carolinian population (Seburn, 1993), and accounts from across the species’ range suggest that aggregation behaviour in females may be most prevalent during the nesting season (Cagle, 1940; Fitch, 1954; Seburn, 1993; Hecnar, 1994). Communal nests are commonly found throughout the range and Hecnar (1994) showed that communal nesting was not a result of limited nesting sites in one Carolinian population (Hecnar, 1994). Another explanation for communal nesting could be that it allows for more continuous egg guarding by females (Fitch, 1954), as females will brood their own eggs as well as eggs from other females (Noble and Mason, 1933; Fitch, 1954; Vitt and Cooper, 1989; Seburn, 1993; Hecnar, 1994). Even eggs from E. laticeps were brooded by female E. fasciatus, although eggs from other more distantly related species or egg models were discarded from the brood (Noble and Mason, 1933). Brooding females will defend the eggs from predators (Fitch, 1954), and Hecnar (1991) has suggested that communal nesting may be a response to predation pressure in one Carolinian population.

Several weeks after mating, females lay one clutch of 9-10 eggs (Fitch, 1954; Seburn, 1990; Hecnar, 1994). Clutch size within a northeastern Kansas population and a Carolinian population was related to size, age and condition of the female (Fitch, 1954; Hecnar and Hecnar, 2005 respectively). Body size, running speed and some growth measures of E. fasciatus hatchlings appear to be influenced by clutch origin (Goodman, 2006), although it is undetermined whether this is due primarily to environmental or genetic effects. Deposition of a clutch probably occurs over a day or two at most (Fitch, 1954).

Eggshells are thin and easily punctured (Fitch, 1954), and it has been suggested that in skinks, the most vulnerable stage in the life cycle is the egg (Fitch and Fitch, 1967). Important physical variables affecting egg development in reptiles, E. fasciatus included, are temperature, moisture, and gas exchange (Packard and Packard, 1988, in Hecnar, 1994). At low moisture levels, eggs are susceptible to desiccation whereas as at high moisture levels eggs may become infected with microbes or gas exchange may be arrested (Fitch, 1954; Fitch and Fitch, 1967).

Despite the vulnerability of this life stage, eggs show relatively high tolerance for moisture, and normal young have successfully hatched from apparently unhealthy or irregularly shaped eggs (Fitch, 1954). Further, embryos of E. obsoletus remained viable after 30-minute exposures to a maximum temperature of 42.4°C and a minimum temperature of -4°C (Fitch, 1964). In E. fasciatus, eggs probably have a temperature tolerance range comparable to that of an adult, although temperature most certainly affects incubation time (Fitch, 1954). For instance, gravid females in a Carolinian population retained their eggs longer than females in a Kansas population (52 days versus 30-44 days respectively) but brooded them for less time (13 days versus 11-32 days, respectively (Fitch, 1954; Seburn and Seburn, 1998). This difference may reflect a behavioural compensation for a shorter active season in more northern populations (Seburn and Seburn, 1998).

Females rarely leave their eggs unattended (Fitch, 1954) and aid in the successful development of their eggs in a variety of ways (Groves, 1982). First, females rotate the eggs in the nest and tend to keep their eggs in a cluster, with most of the egg exposed to air (Fitch, 1954). Frequent moving of the eggs probably ensures that no part of an egg is touching the substrate long enough for rotting to occur, and helps to prevent the eggs from asymmetrical drying or stretching that could lead to irregularly shaped eggs (Fitch, 1954). Females also defend the nest from predators such as mice, other lizards and small snakes, and retrieve eggs that have fallen outside the nest cavity (Noble and Mason, 1933; Vitt and Cooper, 1989). Finally, females relocate nests following a disturbance or a change in environmental conditions (Fitch, 1954; Vitt and Cooper, 1989), possibly to maintain the eggs at a suitable moisture level.

In a Carolinian population, Hecnar (1994) observed that during dry weather, nests were deeper in the soil than in wet weather, and on three occasions nests under logs disappeared during dry conditions and reappeared during wetter conditions, implying that females vertically move eggs according to moisture levels within the nest. Vitt and Cooper (1989) observed nest relocations in South Carolina after heavy rainfall further supporting the notion that females relocate eggs vertically according to soil moisture levels.

Females also vary their brooding position to alter the degree of contact with eggs according to soil moisture (Hecnar, 1994). High contact during low moisture levels likely reduces transpirational losses from the eggs (Somma and Fawcett, 1989; Hecnar, 1994). It has even been suggested that females may void water in the nest during dry conditions to enhance moisture levels (Fitch, 1954; Seburn, 1990; Hecnar, 1990). Female brooding clearly influences nest moisture levels in E. fasciatus, and eggs that were brooded by a female had higher survivorship across all moisture levels than eggs that were unattended (Somma and Fawcett, 1989).

Females maintain an olfactory interest in their eggs throughout incubation (Noble and Mason, 1933; Fitch, 1954). This may help them to locate and retrieve their eggs and to identify addled (spoiled) eggs. Experimental research using brooding females of E. fasciatus indicates that they ingest eggs within 24 hours of the egg showing signs of addling (Groves, 1982). Vitt and Cooper (1986a) suggested that ingestion of live eggs may occur to satisfy the hunger of the brooding female, but Groves (1982) found that brooding females fed ad libitum in a laboratory experiment still ingested eggs, the large majority of which were addled. Ingestion of addled eggs may help to protect the female and her remaining viable eggs (Groves, 1982), as many predators of skinks locate their prey by olfactory cues (Fitch, 1954; Groves, 1982).

Initiation of incubation and duration of incubation vary across the species’ range and even within a population (Noble and Mason, 1933; Fitch, 1954). Generally, hatching occurs in Kansas by mid-July (Fitch, 1954). In Carolinian populations, hatching occurs from late July to early August (Seburn, 1990), and hatching in Great Lakes/ St. Lawrence populations seems to be at a similar time (Seburn and Seburn, 1989), although it may be slightly later due to a later general emergence date (S. Wick, personal communication [pers. comm.]). A comparison of reproductive events between Great Lakes/St. Lawrence and Carolinian populations was made based on intensive research performed within a Great Lakes/St. Lawrence population in 2002 (Wick, 2004; S. Wick, pers. comm.), and a Carolinian population in 1989 (Seburn, 1990; Seburn and Seburn, 1998). Where uncertainty in timing of the events in the Carolinian population exists due to lack of data, maximal time periods are assumed (Seburn and Seburn, 1998).

Table 4. Comparison of reproductive events between a Great Lakes/St. Lawrence (Wick, 2004; S. Wick, pers. comm.) and Carolinian population (Seburn, 1990; Seburn and Seburn, 1998)
Reproductive step Great Lakes/St. Lawrence Population Carolinian Population
General emergence from hibernation Early May to ? April 15 to April 28
Males show breeding colours Late May to early July April 28 to May 25
Females gravid Mid-June to mid-July June 8 to July 17
Females oviposit Early July to mid-July July 12 to July 17
Eggs hatch Early August to ? July 25 to Aug 25
Presumed hibernation (general disappearance or observed burrowing behaviour) Late September August 25 to September 16

Individuals hatch by using an egg tooth over a period of 45 minutes to several hours (Fitch, 1954) and the hatching of an entire clutch is usually completed within 24 hours (Cagle, 1940). Once hatching is complete, the female and hatchlings will disperse within a short time, with the female at times dispersing before the hatchlings (Fitch, 1954). Females and hatchlings have been observed in the nest or nest vicinity a day or two after hatching (Fitch, 1954; Seburn, 1990). Over the incubation period, females lose considerable mass (Seburn, 1990) and, on average, weigh less than a yearling of even smaller snout-vent length (SVL). Often, their tails are noticeably thinner because of depleted lipid reserves, and there may even be kinks in the tail as a result of this loss of tail mass (Fitch, 1954).

Growth and survivorship

Hatchlings were measured to be 23-27 mm in SVL in Kansas (Fitch, 1954). The most rapid growth phase of an individual’s lifetime occurs from hatching until first hibernation. During this phase, hatchlings with accelerated growth rates can achieve a maximum growth rate of about 0.5 mm a day to become ~50 mm in SVL upon entering their first hibernation. One Kansas individual with delayed growth emerged from its first hibernation at only 34 mm SVL (Fitch, 1954). In a Carolinian population, the average growth rate for hatchlings was 0.26 mm/day and the maximum SVL achieved by a hatchling before entering its first hibernation was 48 mm (Seburn, 1990). One individual with delayed growth emerged from its first hibernation with an SVL of only 36 mm. In this same population, the average growth rate for yearlings was found to be 0.18 mm/day, while adult males and females had an average of 0.02 mm/day and 0.08 mm/day respectively (Seburn, 1990).

Most yearlings grow to small adult size during the growing season following their first hibernation, and once this size is attained, growth slows abruptly (Fitch, 1954). In Kansas, once an individual’s SVL reaches approximately 75 mm, growth virtually stops in females, and slows for males, who can attain a maximum size several mm larger than that of females. As individuals age and grow, their colour pattern also changes, and the alteration of the colour pattern is more rapid in males than in females.

The most significant period of mortality (excluding egg mortality) occurs between hatching and emergence from first hibernation (Seburn and Seburn, 1998). Even when individuals reach adulthood, they still face a relatively high probability of mortality. Approximately one hatchling per clutch survives to reproduce (Fitch, 1954). Although Fitch (1956) reported a 10-year-old individual, life expectancy is generally five years. Eumeces fasciatus has a much longer life expectancy relative to similarly sized small mammals that often exist in similar habitats (Fitch, 1954).

True sex ratios are difficult to estimate because of the different behaviours exhibited by males and females throughout the active season. However, Seburn (1990) found that the sex ratio of a Carolinian population during breeding season was not significantly different from 1:1.

Hibernation

The ability to overwinter successfully may influence the northern range limit of some reptiles (e.g. St. Clair and Gregory, 1990; Rosen, 1991) and can have a large effect on the survivorship of individuals and the subsequent persistence of a population. Fitch (1954) showed that although individuals of E. fasciatus can survive brief exposures to temperatures below freezing, they do not survive prolonged exposures to such temperatures.

In E. fasciatus, a variety of hibernation sites are used, and knowledge of specific physical characteristics (e.g. moisture level, temperature range) of hibernacula is lacking. Across the species’ range, hibernation sites include locations under logs (Conant, 1951), under rocks, and in decaying stumps and fallen timber (Neill, 1948). Hibernation sites have been found up to approximately 2.5 m below ground (Tihen, 1937 in Fitch, 1954). Southwestern Ontario individuals may hibernate underground under wood debris in sand dune habitat (S. Hecnar, pers. comm.). 

Skinks show significant aggregation behaviour within sex and age classes and within the general population throughout the year (Hecnar, 1991; Seburn, 1993; Hecnar, 1994), and this behaviour is especially prevalent during hibernation (Fitch, 1954; Cooper and Gartska, 1997). Small groups of hibernating individuals have been observed across the range (e.g. Hamilton, 1948; Neill, 1948; Fitch, 1954). In 1986 and 1987, spring aggregations of 25 individuals and 27 individuals, respectively, were found in a Carolinian population suggesting that aggregations of hibernating skinks also occur in Ontario’s populations (Weller and Oldham, 1988). Aggregation in hibernation sites could reflect a lack of suitable hibernation sites, but this explanation seems unlikely. Experimental research on E. laticeps showed that individuals had a tendency to aggregate despite the presence of multiple artificial hibernation sites. It was also found that aggregation was more likely to occur during periods of low temperatures, implying that there may be a thermal benefit to aggregation behaviour during hibernation (Cooper and Gartska, 1987).

Food habits

Eumeces fasciatus is mainly insectivorous (Fitch, 1954). The diet includes insects, insect larva, arachnids, earthworms, and occasionally small crustaceans and vertebrates (Taylor, 1936; Fitch, 1954). Newborn mice, bird’s eggs, and smaller lizards are possible prey items (Netting, 1939 in Fitch, 1954), but the smallest newborn mice are near the maximum size of prey that could possibly be swallowed by the largest adults of E. fasciatus (Fitch, 1954). Individuals often consume their shed skin, and will sometimes cannibalize other individuals of E. fasciatus. Stomach content and scat analysis on individuals in Kansas revealed that the diet consisted of arachnids (49%), insects (43%), and very small amounts of sloughed skin, skink eggs, and skink hatchlings (under 1% each) (Fitch, 1954). Scat analysis in one Carolinian population (Rondeau Provincial Park) revealed that crickets were the most common food item. Other prey included snails, spiders, cockroaches, sow bugs and caterpillars (Judd, 1962). More recent scat analyses performed in another Carolinian population (PPNP) indicated that the most common prey of skinks were arachnids (Hecnar et al., 2002).

Eumeces fasciatus is an active forager and locates prey by chemical perception and visual stimuli (Fitch, 1954; Burghardt, 1964). When presented with odours of known prey species, individuals displayed elevated tongue-flick rates, oriented to the odour source and sometimes even bit the odour source (Burghardt, 1964). Individuals feeding on crickets were observed to catch the cricket, shake it laterally often causing the cricket to be released from the skink’s grip, and then retrieve it and repeat the process (Fitch, 1954; B. Howes, pers. obs.). Burghardt (1964) found that individuals preferred larger, moving prey relative to smaller, non-moving prey. Individuals can ingest crickets that are almost the size of their own body diameter (Fitch, 1954; B. Howes, pers. obs.).

The amount of food ingested by individuals varies with age and throughout the season (Fitch and von Achen, 1977), and according to temperature and activity of the individual (Fitch, 1954). Food consumption by males was found to increase through the early summer and then decrease suddenly in mid-September. Females showed a similar pattern in food consumption, except that even non-brooding females typically decreased food consumption during the brooding period. The average food consumption by juveniles decreased gradually in the autumn (Fitch, 1954). Adult skinks in captivity ate roughly 3% of their body weight per day (0.195 g), whereas juvenile skinks ate 6.11% of their body weight per day (Fitch and von Achen, 1977). Scats of E. fasciatus are roughly 10-20 mm long, 2-4 mm in diameter, straight, cylindrical and capped at one end with uric acid. Typically, they primarily consist of the chitinous fragments of arthropod prey (Fitch, 1954; Judd, 1962; Hecnar et al., 2002).

Predation

Identified predators of E. fasciatus include raccoons, hawks, foxes, minks, weasels, skunks, opposums, armadillos, snakes, moles, and shrews. Based on scat analysis and experimental predation observations, Fitch (1954) suggested that short-tailed shrews were one of the major predators of skinks in his Kansas study site. Cats and dogs are also predators of skinks (Fitch, 1954; Oldham and Weller, 2000; B. Howes, pers. obs.). Cooper (1990) showed that individuals of E. laticeps can distinguish between predator and prey odours, and that they can also distinguish between odours of snake species that do and do not prey on them.

The reactions of E. fasciatus to predators vary greatly depending on the individual and the circumstances. Most often, individuals rely on concealment rather than escape tactics or aggression and respond to a potential predator by “freezing” (Fitch, 1954). Their movements become even more erratic and jerky when they are frightened, and they are especially elusive during warmer temperatures. Although they are primarily terrestrial, they are also adept at burrowing and climbing. Tree-climbing is a common escape tactic for individuals of both sexes and all ages (Fitch, 1954; S. Hecnar, pers. obs.). Individuals have even been observed to take refuge in water (Parker, 1948 in Fitch, 1954), and pull themselves through submerged vegetation (B. Howes, pers. obs.).

Tail autotomy

When harassed by a potential predator, individuals of E. fasciatus can autotomize their tails as a defence mechanism. Once severed, the tail will thrash for up to several minutes, distracting the predator so that the lizard can escape (Fitch, 1954). The vivid blue colour of the tail is an attractant for potential predators (Cooper and Vitt, 1985), and because tail colouration fades with age, it is thought that the risk of predation is highest during the juvenile life stage (Vitt and Cooper 1986b). Vitt and Cooper (1986b) suggested that a high proportion of predation attempts are directed to the tail because of its colouration and movement behaviour. They exposed juvenile E. fasciatus to snake attacks, and found that attacks at the base of the tail were more frequent on juveniles with complete tails than on juveniles who had their tails removed or painted black. They also showed that juveniles lash their tails more frequently than adults. Attacks directed at the tail caused the skink to autotomize it and subsequently escape, while attacks directed at the body resulted in a successful predation event (Vitt and Cooper, 1986b).

Although tail autotomy may be an effective predator avoidance mechanism, it may also be costly, as it could impair locomotion, result in loss of social status, and reduce growth or reproduction (Goodman, 2006). Two of these potential costs of tail autotomy in E. fasciatus have been examined. Tail loss in hatchling skinks was not associated with sacrificed growth in body mass or SVL (Vitt and Cooper, 1986b; Goodman, 2006). Juvenile E. fasciatus that underwent full tail autotomy regenerated tails at an average of 6.11 mm/week, a faster growth rate than that observed in juveniles that had only partial tail autotomy. Full tail autotomy was associated with significantly decreased maximum sprint speed in juveniles; however, this effect disappeared within four weeks after tail loss (Goodman, 2006). Costs of tail autotomy have not yet been examined in adults, although it is known that the tail contains over half of the standing lipid content in females and almost half of the standing lipid content in males (Vitt and Cooper, 1986b).

Fitch (1954) measured the incidence of tail loss in his Kansas study population. He found that tail loss had occurred in approximately 25% of 1-month old juveniles, 50% of 1 to 3 month olds, and 75% of 1 year olds. Incidence of broken or regenerated tails in adult females is slightly higher than in adult males, perhaps because of nest guarding and sluggishness resulting from nesting period. Only 16.5% of adult females had their complete original tail (Fitch, 1954).

Physiology

Like other reptiles, individuals of E. fasciatus thermoregulate by adjusting their microhabitat use to maintain core body temperature within an optimal range. By using a terrarium that had extremes of temperatures at each end, Fitch (1954) determined that the preferred temperature range of E. fasciatus was 28-36°C, although their temperature tolerance range is much broader. Individuals were found to survive temperatures as high as 42°C, but it should be noted that during periods of high temperatures skinks are observed less frequently and may become more fossorial (Fitch, 1954; Seburn and Seburn, 1998; B. Howes, pers. obs.). Individuals were also found to survive temperatures as low as –1°C for short periods of time (less than 30 minutes), and are mobile at temperatures below those at which most North American reptiles are capable of moving (Fitch, 1954). The species’ relative cold tolerance compared to other reptiles is likely associated with its status as one of the most northerly lizard species and its classification as a primary herpetological invader following the most recent glacial retreat (Holman, 1995).

Temperatures in Great Lakes/St. Lawrence populations are generally far from the optimum for reptiles (Row and Blouin-Demers, 2006), possibly making microhabitat selection especially important in these northern populations. In two of these populations, during late May and early June, individuals of E. fasciatus selected rocks as cover elements that provided them with thermal conditions that most closely matched their preferred body temperature range. Presumably, this allows them to maximize time at temperatures that optimize physiological processes (Quirt et al., 2006).

Movement and dispersal

Eumeces fasciatus is not territorial, but individuals tend to limit their activities to small, familiar areas. Individuals do have home ranges, although boundaries are not strictly defined. The size of a home range depends on the sex and age of an individual as well as the type of habitat, but was estimated to be between 270 m² and 578 m² for individuals in a Kansas population (Fitch, 1954). Within these ranges, individuals often follow natural travel routes, moving along rock faces or fallen logs (Fitch, 1954). If any homing instinct exists within E. fasciatus, it is likely very weak. Fitch (1954) found that the composition of his Kansas study populations differed from year to year, presumably because individuals tended to shift their home ranges. Mark-recapture experiments have revealed that, although individuals have been found up to 208 m from the original point of capture, they are generally recaptured within a short distance of the previous capture (Fitch, 1954). The average movement between captures recorded for 323 recaptured individuals in Kansas was 18 m (Fitch, 1954). Individuals moved an average of 5.1 m per day (Fitch and von Achen, 1977), although activity levels have been shown to differ between males, females, and juveniles (Fitch and von Achen, 1977; Seburn, 1993).

The average movement between captures of Kansas individuals throughout a season was 21 m for males, 14 m for females, and 19 m for juveniles (Fitch, 1954). The maximum distance between any two captures was 119 m for males and 99 m for females (Fitch and von Achen, 1977). In a Carolinian population, the maximum hatchling movement recorded was at least 107 m, while the maximum yearling movement was at least 25 metres (Seburn, 1993).

Adult males tend to undertake longer movements outside of their home range during the breeding season, while adult females tend to make longer movements outside their home range to find a suitable nest site (Fitch, 1954; Seburn, 1993). Females make small movements during the breeding and nesting periods, but become more active following the nesting period (Fitch and von Achen, 1977), and tend to return to their original home range after their eggs have hatched (Seburn, 1993). Juveniles are more active than adults throughout the season (Fitch and von Achen, 1977) and tend to shift to new areas more frequently than adults (Fitch, 1954). Genetic research performed in one Great Lakes/St. Lawrence population revealed that no age or sex class tended to disperse more than another, but because females may leave their home range to nest, hatchlings are born outside of the maternal home range and could therefore be considered the “dispersers” of the species (Wick, 2004).

Interspecific interactions

Eumeces fasciatus is host to several endoparasites and ectoparasites. Small nematodes and flukes have been observed in the feces and small white cysts have been observed in several dissected individuals (Fitch, 1954). Two previously unidentified species of endoparasites (Eimeria fasciatus and Isospora scinci) that were found in the intestine of E. fasciatus could be specialists on the species (Upton et al., 1991). The most common ectoparasites of E. fasciatus are chiggers (Trombicula spp.; Wharton and Fuller, 1952, in Fitch, 1954), which commonly attach themselves to the skin of the limb axes (Seburn and Seburn, 1998; B. Howes, pers. obs.). Chiggers have been observed on individuals in a Carolinian population where the frequency and level of infection seemed to increase throughout the summer. Periodic shedding of the skin for growth seems to reduce the frequency and level of infection (Seburn and Seburn, 1998).

Adaptability

Eumeces fasciatus is intolerant of unsuitable humidity levels and a permanent body of water is a requirement in any habitat (Fitch, 1954). It appears to be relatively tolerant to a wide range of temperatures, although unusually cool weather conditions can delay oviposition or hatching. This could result in delaying sexual maturity in a large proportion of young, drastically reducing the reproductive potential of a population. The percentage of such delays in attainment of sexual maturity is likely to increase in more northerly populations (Fitch, 1954), and may be of particular concern in Great Lakes/ St. Lawrence populations. These populations exist in more extreme climatic conditions than the Carolinian populations. For instance, the mean daily January and July temperatures were noted for seven Great Lakes/St. Lawrence populations and two Carolinian populations based on records from the nearest weather stations (Howes and Lougheed, in review). The mean daily January temperature was -9.5°C for Great Lakes/ St. Lawrence populations, and -4.1°C for Carolinian populations. The mean daily July temperature was 20.3°C for Great Lakes/St. Lawrence populations, and 22.3°C for Carolinian populations (Howes and Lougheed, in review; Environment Canada, 2006).

Fluctuating water levels could increase genetic connectivity among populations that are normally isolated by water in a heterogeneous environment (Wick, 2004). High lake levels may contribute to overwintering losses, especially in Carolinian populations that exist on the shores of Lakes Erie and Huron (Hecnar and Hecnar, 2005). Eumeces fasciatus is intolerant of natural succession processes that alter its early successional habitat. Indeed, the populations that Fitch (1954) studied intensively have now virtually disappeared because of succession (H. Fitch, pers. comm.). Infrequent fires can help to maintain the early successional habitat required by the species, but can also cause a large decline in numbers at a particular site. A fire within a Connecticut population may have eliminated an entire cohort (Gruner, pers. comm. in Seburn and Seburn, 1998). Mushinsky (1992) showed that individuals of E. inexpectatus in Florida were more common on sites that had not been burned for 20 years or were burned on a 5-7 year cycle compared to sites that were burned on a 1-2 year cycle. Less frequently burned sites had significantly more leaf litter, which likely provides more suitable habitat to secretive skinks (Mushinsky, 1992).

Skinks can exist in anthropogenically altered habitats, and may actually thrive in these situations by making use of artificial objects, such as wood piles, and scrap tin and plywood boards. However, this capacity is mainly restricted to areas that retain some aspects of natural habitat (e.g. maintenance yards within protected parks, rock gardens surrounding a house in a rural area). Skinks are not found in urbanized areas. Although skinks are likely relatively resilient to short-term minor disturbances, their tolerance may be greatly reduced during the nesting period (Hecnar and M’Closkey, 1988). Brooding females that are disturbed can abandon their nest (Hecnar and M’Closkey, 1988), possibly resulting in high egg mortality (Hasegawa, 1985). In one Carolinian population (PPNP), E. fasciatus has been shown to be intolerant to loss of microhabitat structures (Hecnar and M’Closkey, 1988).

As previously mentioned, northern populations of E. fasciatus have significantly reduced levels of intra-population genetic diversity relative to central, eastern, and southern populations of the species (Howes and Lougheed, in review). This reduction in genetic diversity could inhibit the evolutionary potential and adaptability of Ontario’s populations.

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