SFFO - Sand Skink Recovery Plan (original) (raw)
| Sand Skink |  |
|---|---|
| (Neoseps reynoldsi) |
| Introduction Description Taxonomy Distribution Habitat Behavior Relationship to Others Species Status and Trends Management Literature Cited Recovery Tasks | Federal Status: | Threatened (November 6, 1987) |  |
|---|---|---|---|
| Critical Habitat: | None Designated | ||
| Florida State Status: | Threatened | ||
| Recovery Plan Status: | Revised (May 1999) | ||
| Geographic Coverage: | Endangered |
The sand skink is a small, fossorial lizard that occurs on the sandy ridges of interior central Florida from Marion County south to Highlands County. The sand skink is highly adapted for life in the sand; it spends the majority of time below the surface �swimming� in� loose sand in search of food, shelter, and mates. The species is vulnerable because of habitat loss due to agricultural and residential uses and from habitat degradation due to fire exclusion. Efforts to protect the sand skink and other xeric upland species are underway and include the acquisition, protection, and management of a number of xeric upland sites. Recovery of the sand skink will require management of conservation lands, restoration of habitat and possible reintroduction of individuals into successfully-rehabilitated habitat.
This account represents a revision to the existing recovery plan for the sand skink (FWS 1993).
Description
The sand skink (Neoseps reynoldsi) reaches about 13 cm, about half of which is tail. It is slender, shiny and usually gray to grayish-white, although it may occasionally be light tan. Hatchlings have a wide black band extending from the tip of the tail to the snout along each side. This band is reduced in adults and may only occur from the eye to snout on some individuals (Telford 1959). The sand skink�s legs are vestigial and practically nonfunctional. Other adaptations to a fossorial existence include greatly reduced eyes, lack of external ear openings, a wedge-shaped snout, and a countersunk lower jaw.
Taxonomy
The monotypic genus Neoseps was established by Stejneger (1910) in describing the uniquely fossorial� sand skink of the central Florida sand ridges.
Distribution
The sand skink is endemic to the sandy ridges of central Florida, occurring in� Highlands, Lake, Marion, Orange, Osceola, Polk, and Putnam counties (Figure 1) (Christman 1988). Principal populations occur on the Lake Wales and Winter Haven Ridges in Highlands, Lake, and Polk counties (Christman 1992; Mushinsky and McCoy 1995; P. Moler, GFC, personal communication 1998). The sand skink is uncommon on the Mount Dora Ridge, including sites within the Ocala NF�(Christman 1970, 1992). As of 1997, there were 114 locality records for the sand skink, most of which are found within the Lake Wales Ridge.
Habitat
The sand skink is widespread in xeric uplands with sandy substrates, but appears to be most abundant in ecotonal areas, typically between high pine and scrub (Telford 1996). It is also found in rosemary (Ceratiola ericoides) scrub, turkey oak barrens or sandy areas of the high pine community (Campbell and Christman 1982). Areas free of abundant plant roots, with open canopies, scattered shrubby vegetation, and patches of bare sand are optimal habitats (Christman 1978, 1992). However, recent surveys have located sand skinks in areas with dense undergrowth and extensive canopy closure (H. Mushinsky, University of South Florida, personal communication 1996), indicating that extensive loose, root free soils may not be a requisite for this species. Suitable habitat must also provide soil moisture conditions that provide for� thermoregulation and egg incubation, as well as create conditions favorable for the skink�s prey (Telford 1959).
The density of the sand skink varies considerably, ranging from about 5 to 23 individuals per 0.025 ha (Sutton 1996). Differences in abundance are attributed to habitat suitability. The sand skink is typically found 5 to 10 cm below the surface, where it burrows or �swims� (Carr 1940) through the sand to obtain its prey. Seasonally, sand skinks are most active from mid-February through mid-May and again in late summer-early fall. Activity patterns suggest sand skinks are active during the morning and evening, patterns typically associated with thermoregulatory behaviors (Andrews 1994).
Campbell and Christman (1982) had earlier characterized Neoseps as �colonizers of a patchy, early successional, or disturbed habitat type which occurs throughout the sandhill, scrub, and xeric hammock vegetative associations as a result of biological (Gopherus, e.g.) or catastrophic (fire) factors.�� Susceptibility of mature sand pine to windthrow may be an important factor in maintaining bare, sandy microhabitats required by sand skinks and other scrub endemics (Myers 1991). _Neoseps_has persisted in old growth stands of scrub (greater than 60 years old) on Archbold Biological Station in the vicinity of firelanes, suggesting that artificial clearings may be important to N. reynoldsi.
Behavior
Reproduction
Telford (1959) found sand skinks to be most active from early March through early May, whereas Sutton (1996) found skinks to be most active from mid-February to late April. These high-activity periods correspond to movements associated with breeding season activities. After high-activity periods, females are difficult to collect, apparently due to nesting activity. Approximately 55 days after mating, about two eggs are laid in the sand, under logs or debris, in early summer (Telford 1959). The eggs hatch from June through July. No information is available on the dispersal of this species or its territory size.
Sand skinks reach sexual maturity at 1 to 2 years (Telford 1959, Sutton 1996) and may remain reproductively active for 2 to 3 years (Sutton 1996).
Feeding
Sand skinks feed on a variety of hard and soft-bodied arthropods that occur below the ground surface. Diel patterns of activity suggest sand skinks are active during the day, and probably feed primarily during the morning and late afternoon when their preferred body temperatures are achieved (Sutton 1996). Most of their diet consists of beetle larvae and termites (_Prorhinotermes_spp.). Spiders, larval ant lions, lepidopteran larvae, roaches and adult beetles are also eaten (Myers and Telford 1965, Smith 1977).
Relationship to Other Species
Mushinsky and McCoy (1991) contrasted vertebrate species distribution in three size classes of �relatively-open canopied� and �relatively-closed canopied� scrub on the Lake Wales Ridge. Mushinsky and McCoy (1991) reported a negative correlation between the rank abundance of Florida scrub jays (Aphelocoma c. coerulescens) and abundance of sand skinks. It is unclear whether this relationship is due to ecological interactions between species or� differences in xeric habitat that favor one species over another. Though we know of no specific records of scrub jays preying on sand skinks, it is likely that they take them opportunistically. It has also been suggested that management of scrub habitat often focuses on maintaining habitat for the threatened scrub jay, which may not be compatible with the habitat requirements of the sand skink. The relationship between presence of scrub jays, oak canopy closure, and the sand skink requires further investigation.
In many locations, sand skinks are sympatric with the peninsula mole skink (Eumeces egregius onocrepis), blue-tailed mole skink (E. e. lividus), Florida scrub lizard (Sceloporus woodi), and the Florida crowned snake (Tantilla relicta), but these species apparently do not compete because of resource partitioning (Smith 1977, 1982; Campbell and Christman 1982).�
Status and Trends
The modification and destruction of xeric upland communities in central Florida was a primary consideration in listing the sand skink as threatened under the ESA in 1987 (52 FR 42662). By some estimates, as much as 90 percent of the scrub ecosystem has already been lost to residential development and conversion to agriculture, primarily citrus groves (Florida Department of Natural Resources 1991, Kautz 1993). Xeric uplands remaining on private lands are especially vulnerable to destruction because of increasing residential and agricultural pressures.
Except for a few locations where intensive research has been conducted, we have very little information about the presence or abundance of� N. reynoldsi, not to mention the status and trends of this species in South Florida. The species� diminutive size and secretive habits make its study difficult.� For example, the status and trends of sand skinks on Ocala NF remains uncertain, despite fairly intense research efforts. A 1992 survey was conducted to provide information on the distribution of sand skinks in the Ocala NF in relation to forest management practices (clear-cutting, burning, bracke and broadcast seeding). No sand skinks were captured during 18,578 trap nights from stands close to historical locality records for Neoseps, although a number of other fossorial reptiles were recovered. Telford (1992) cited the ephemeral nature of early successional scrub habitats due to dynamic successional changes as an important confounding factor in the evaluation of the sand skink�s present status in the Ocala NF.
More recent studies have provided new information about the distribution of N. reynoldsi, but little information is currently available to assess the species� status or trends. Mushinsky and McCoy (1991) captured N. reynoldsi during their evaluation of vertebrate use of xeric uplands of central Florida. However, their study only provided presence/absence information. Similarly, Stout and Corey (1995) reported the presence of N. reynoldsi at several locations during their evaluation of the ecological implications of the fragmentation of xeric upland communities. The first estimates of absolute densities of N. reynoldsi in various habitat types and basic life history information were provided by Sutton (1996). Unfortunately, no long-term monitoring efforts have been undertaken to evaluate the status or trends of N. reynoldsi at these or other sites.
At the time of Federal listing in 1987, Florida Natural Areas Inventory had recorded 31 known sites for the sand skink. By 1997, 114 localities were known. This increase is largely the result of more intensive sampling of scrub habitats in recent years and does not imply that this species is more widespread than originally thought. On the contrary, we believe that continued residential and agricultural development of xeric upland habitat in central Florida has destroyed or degraded habitat containing N. reynoldsi. Estimates of habitat loss range from about 60 to 90 percent for xeric upland communities (Christman 1988, Christman and Judd 1990, Kautz 1993, Center for Plant Conservation 1995).