Carolina Gopher Frog
|Taxonomic Notes: This species was placed in the genus Lithobates by Frost et al. (2006). However, Yuan et al. (2016, Systematic Biology, doi: 10.1093/sysbio/syw055) showed that this action created problems of paraphyly in other genera. Yuan et al. (2016) recognized subgenera within Rana for the major traditional species groups, with Lithobates used as the subgenus for the Rana palmipes group. AmphibiaWeb recommends the optional use of these subgenera to refer to these major species groups, with names written as Rana (Aquarana) catesbeiana, for example.|
© 2019 Nathan Shepard (1 of 14)
Rana capito Le Conte, 1855
John B. Jensen1
A recent genetic study of gopher frog (Rana capito) populations across the current geographic distribution (Mississippi–North Carolina) by Young and Crother (2001) indicated that the Mississippi population was genetically distinct. Young and Crother (2001) therefore elevated the Mississippi population to specific status by resurrecting Rana sevosa Goin and Netting (1940; dusky gopher frog), because this population is the only one remaining in the historical geographic range of Rana sevosa (Louisiana to Mobile County, Alabama) as described by Goin and Netting (1940). Assigning the population discovered in Baldwin County, Alabama, after the publication of Goin and Netting (1940) to R. sevosa or R. capito is difficult because this population was not included in their study and has since gone extinct. Netting and Goin (1942a) assigned this population to R. sevosa based on the then known distribution of R. sevosa (Louisiana to Mobile County, Alabama) and R. capito (Florida to North Carolina). However, populations later discovered in counties proximate to Baldwin County were included in the genetic study of Young and Crother (2001) and were not genetically distinct from all other populations sampled east of the Mobile Bay (thus remaining R. capito). Based on this evidence, we assign the Baldwin County population to R. capito (as indicated by the geographic range maps) and note the inherent uncertainty. It currently is not possible to determine the location of the contact zone between R. sevosa and R. capito, but the extensive Mobile Basin creates a logical barrier to dispersal and thus probably separates the two species.
1. Historical versus Current Distribution. Historically, gopher frogs (Rana capito) were distributed throughout the Gulf and Atlantic Coastal Plain from southeastern Alabama to North Carolina (Bailey, 1991), with one isolated population known from the Ridge and Valley Province of Alabama (Mount, 1975). Though the species continues to be documented from many new localities within its range (for example, Palis and Jensen, 1995; Stevenson and Davis, 1995), this is undoubtedly due to the increased survey efforts of remaining suitable lands rather than recent colonization. The recent discovery of two Rana cf. capito individuals from a site in the Cumberland Plateau of Tennessee (Miller and Campbell, 1996; B.T. Miller, personal communication) is of great interest and may represent a substantial range extension. Young and Crother (2001) recently provided allozyme data supporting the separation of R. capito from both R. areolata (crawfish frogs) and R. sevosa (dusky gopher frogs).
2. Historical versus Current Abundance. Gopher frogs are considered Endangered, Threatened, or of Special Concern in all of the states within their range (Mount, 1975; Martof et al., 1980; Moler, 1992a; Levell, 1997). Though little data are available concerning changes in the species’ abundance, much information exists on the reduction of their habitat and breeding sites. The longleaf pine (Pinus palustris) community, the ecosystem primarily inhabited by gopher frogs, has been reduced to < 5% of its historical range (Frost, 1993; Outcalt and Sheffield, 1996; Means, 2003a), and gopher frogs are just one of many component endemic or nearly endemic species declining as a result of this loss. Means and Means (2000) found that the number of breeding populations of gopher frogs in the Munson Sand Hills of panhandle Florida occur at a much lower percentage on sand pine silviculture lands than in nearby native longleaf pine habitat, and that some historical breeding populations have been extirpated. They hypothesized that the principal reason is intensive soil disturbance resulting in the elimination or severe alteration of the upland habitat. Bailey (M.A., 1994) reported that 8 of 14 known breeding sites in Alabama are considered historical, and of the 6 extant ponds, only 3 supported substantial populations. However, since that study, one “historical” site has been reconfirmed as extant, two additional breeding ponds have been discovered, and one previously known breeding site has been extirpated due to the introduction of predatory fish (M.A. Bailey, personal communication; J.B.J., personal observations). Although a few new North Carolina sites have been documented in recent years (Beane and Hoffman, 1995, 1997), Braswell (1993) found only 11 of 32 previously known breeding sites to be active in North Carolina. Twelve sites are known from South Carolina, though only four remain extant (S. Bennett, personal communication). Of 23 historical Georgia gopher frog breeding sites investigated by Seyle (1994), 12 were judged suitable, 8 were considered degraded but marginally suitable, and 3 were judged unsuitable. Only one site was found to contain gopher frogs during two extensive surveys of Georgia's Coastal Plain in late winter and early spring of 1995; however, heavy rains during the autumn of the previous year may have contributed to early breeding, and therefore, low detectability during the survey period (Moulis, 1995a,b). Extensive surveys are lacking for Florida.
3. Life History Features.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Throughout most of their range, gopher frogs migrate from terrestrial habitats to breeding ponds in winter and early spring (primarily January–April). However, breeding migrations may occur at other times of the year following exceptionally heavy rains, especially those associated with tropical disturbances or hurricanes. Fall breeding (typically October–November) has been documented in Alabama (Bailey, 1991), Florida (Palis, 1998; J.B.J., personal observations) and Georgia (J.B.J., personal observations). Gopher frogs often breed during summer in central and south Florida (Godley, 1992). Julian Harrison (personal communication to S. Bennett) has heard calling males, not necessarily indicative of breeding, in every month of the year in South Carolina (S. Bennett, personal communication).
Several migrations may occur throughout the breeding season, with males arriving at reproductive sites prior to females and remaining there longer (Bailey, 1991). Local populations increase during the breeding season as frogs from distant populations take up temporary residence in terrestrial retreats along the way (Franz, 1986). Movements are positively correlated with rainfall and warm temperatures and take place between sunset and sunrise (Bailey, 1991). Individuals enter and exit breeding ponds by approximately the same route (Bailey, 1991; Palis, 1998). Franz et al. (1988) recorded the longest known migration distance (2 km) between breeding site and terrestrial retreat.
ii. Breeding habitat. Typically, gopher frogs breed in either temporary or semi‑permanent ponds that are shallow, have an open canopy and emergent herbaceous vegetation, and lack large, predatory fish (Moler and Franz, 1987; Bailey, 1991). Cypress (Taxodium ascendens) ponds are often utilized in Florida and southeast Georgia (Godley, 1992; Stevenson and Davis, 1995; J.B.J., personal observations). Anthropogenic habitats, such as ditches and borrow pits, are occasionally used (Means, 1986b; Jensen and LaClaire, 1995; J.B.J., personal observations).
i. Egg deposition sites. Within breeding wetlands, egg masses are typically attached to vertical stems of upright emergent or submergent herbaceous vegetation (Bailey, 1990; J.B.J., personal observations). The stems of inundated shrubs such as St. John's wort (Hypericum spp.) and myrtle-leaf holly (Ilex myrtifolia) also serve as egg deposition substrates (Bailey and Jensen, 1993; Palis, 1998).
ii. Clutch size. Egg masses are fist‑sized clusters (Bailey, 1990), and the mean number of eggs/mass have been reported as 1,244 in Georgia (Phillips, 1995); 2,210 in Florida (Palis, 1998); and 1,500–2,000 in North Carolina (Braswell, 1993). Bailey (1989) reported 1,709 eggs for a single mass in Alabama. Apparently, each female deposits only a single egg mass (Palis, 1998).
C. Larvae/Metamorphosis. Studies have shown the length of larval period in the lab ranges from 113–225 days (Phillips, 1995). Palis (1998) documented a larval period of 7 mo at a breeding site in western Florida. Cooler water temperatures may inhibit growth (Phillips, 1995). Larvae transform at 28–37 mm SVL (Franz, 1986; Palis and Jensen, 1995; Semlitsch et al., 1995). Larvae are grazing herbivores and utilize dense emergent and submergent vegetation for cover (J.B.J., personal observations).
D. Juvenile Habitat. Recently metamorphosed and immature gopher frogs are thought to require the same terrestrial habitats as adults.
E. Adult Habitat. Xeric, fire enhanced habitats, especially longleaf pine–turkey oak (Quercus laevis) sandhill (Palis, 1995a). Other habitats used include pine flatwoods, sand pine (Pinus clausa) scrub, and xeric hammocks (Godley, 1992). Adults seek refuge in the burrows of gopher tortoises (Gopherus polyphemus; Franz, 1986; Jackson and Milstrey, 1989), oldfield mice (Peromyscus polionotus; Gentry and Smith, 1968; Lee, 1968b), and crayfish (Godley, 1992; Phillips, 1995), as well as within stump holes (Wright and Wright, 1949). Nickerson and Celino (2003) report that gopher frogs use the hollow interiors of previously submerged and partially decomposed willow (Salix sp.) tree branches as shelters during droughts.
F. Home Range Size. Franz et al. (1988) documented a 2-km movement between an upland retreat and a breeding site in Florida. Phillips (1995) followed two adults for 43 d at a Georgia site and found that both remained within a 10-m radius of the specific burrow they selected. Blihovde (1999) also found strong burrow fidelity, especially among females, at sites monitored in central Florida.
G. Territories. In terrestrial habitats, rarely is > 1 individual in occupancy of a single burrow (Wright and Wright, 1949; R. Franz, personal communication). Male–male combat was observed in dusky gopher frogs (R. sevosa) at a breeding pond in Mississippi (Doody et al., 1995), which may suggest that calling territories are established by these closely related species. Additionally, Jensen et al. (1995) suggested that the unusual submerged calling behavior often exhibited by male gopher frogs may be associated with territory establishment.
H. Aestivation/Avoiding Dessication. Unknown. On warm evenings, gopher frogs are known to emerge from burrows to feed (Wright and Wright, 1949; Means, 1986b; Blihovde, 1999). Nickerson and Celino (2003) observed gopher frogs using partially decomposed willow branches as shelters during droughts.
I. Seasonal Migrations. See “Breeding migrations" above.
J. Torpor (Hibernation). Because gopher frogs breed during the winter (Mount, 1975), hibernation or torpor is thought to be nonexistent.
K. Interspecific Associations/Exclusions. Gopher frogs are one of at least 57 vertebrates known to use the burrows of gopher tortoises (Jackson and Milstrey, 1989) for fire avoidance, predator protection, feeding, and/or escape from excessively cold or warm temperatures. Within, and especially outside of, the range of gopher tortoises, gopher frogs may also seek shelter in burrows created by oldfield mice (Peromyscus polionotus; Gentry and Smith, 1968; Lee, 1968b) and crayfish (Godley, 1992; Phillips, 1995). Blihovde (2000b) found that in addition to gopher tortoise burrows, which were common at his study site in peninsular Florida, gopher frogs used the burrows of southeastern pocket gophers (Geomys pinetis) as non-breeding seasonal retreats. However, gopher frogs are not wholly dependent on the burrows made by other animals since they also retreat into stump holes (Wright and Wright, 1949). Other frog species found in breeding aggregations with gopher frogs include southern leopard frogs (R. sphenocephala), ornate chorus frogs (Pseudacris ornata), southern chorus frogs (P. nigrita), southern cricket frogs (Acris gryllus), and southern toads (Bufo terrestris).
L. Age/Size at Reproductive Maturity. Females are 75–76 mm SVL upon reaching their first breeding season (Bailey, 1991) and are presumed to be 2 yr old (Bailey, 1991; Phillips, 1995). A study conducted in the Florida Panhandle suggests that males reach reproductive maturity at 1.5 yr (Palis, 1998).
M. Longevity. Bailey (1991) indicated that females have a life span of perhaps 6 yr, although that figure was based on a statistically insignificant cluster of size classes. In captivity, Braswell (1993) maintained a gopher frog to 7 yr old (sex unnoted).
N. Feeding Behavior. Adult gopher frogs feed on invertebrates, such as beetles, hemipterans, orthopterans, arachnids, and annelids (Deckert, 1920; Carr, 1940a; Wright and Wright, 1949), as well as on other anurans (Godley, 1992), especially toads (Dickerson, 1906). Feeding is primarily nocturnal (Means, 1986b) and is thought to occur in close vicinity to, and possibly within, utilized burrows. Captives feed readily on crickets, earthworms, and young mice (Braswell, 1993).
O. Predators. On two occasions, Jensen (2000) observed the predation of adult gopher frogs by banded water snakes (Nerodia fasciata fasciata) in a western Florida breeding pond. At another pond in western Florida, a Florida softshell turtle (Apalone ferox) was observed feeding on an adult gopher frog (J.B.J, unpublished data). However, it was not known whether the turtle had killed the frog or the frog had first died and was being scavenged.
Banded water snakes will also eat gopher frog tadpoles (Aresco and Reed, 1998). Additionally, under laboratory conditions, tadpoles have been consumed by common garter snakes (Thamnophis sirtalis), black swamp snakes (Seminatrix pygea), snapping turtles (Chelydra serpentina), chicken turtles (Deirochelys reticularia), common musk turtles (Sternotherus odoratus), dragonfly naiads, and backswimmers (Travis et al., 1985; Cronin and Travis, 1986; Phillips, 1995; M.A. Bailey, personal observations). Tadpoles are palatable to predatory fishes (LaClaire and Franz, 1991) that occasionally colonize or become unnaturally introduced into the isolated wetlands used by gopher frogs. The introduction of bluegill (Lepomis macrochirus) and mosquitofish (Gambusia affinis) into a pond in south‑central Alabama is strongly suspected for the lack of continued breeding by gopher frogs there (Jensen, 1995).
Eastern newts (Notophthalmus viridescens) and trichopteran larvae (Insecta) have been observed feeding on the eggs of gopher frogs (Bailey, 1989).
P. Anti‑Predator Mechanisms. As with many other anurans, adult gopher frogs will inflate their bodies when grasped by potential predators (J.B.J., personal observations). Additionally, adults often slightly curl up and cover their eyes with their forefeet when threatened (J.B.J., personal observations). However, this behavior may have evolved as a defense from potential eye injury as a result of trampling by gopher tortoises in co‑occupied burrows (D.B. Means, personal communication).
Q. Diseases. Unknown.
R. Parasites. Ticks (Ornithorus turcicata) have been found on gopher frogs and other vertebrates that share gopher tortoise burrows, including the tortoises themselves. However, these ticks apparently cause no harm to gopher frogs (Milstrey, 1984; Blihovde, 2000a). This tick species is capable of transmitting relapsing fever to humans and other animals and is also a potential vector of African swine fever (Milstrey, 1984).
4. Conservation. There is concern about the status of gopher frogs in all the states within their range (Mount, 1975; Martof et al., 1980; Moler, 1992a; Levell, 1997), but they are afforded legal protection only in North Carolina (Special Concern), Florida (Special Concern), and Alabama (Protected). The U.S. Fish and Wildlife Service is currently evaluating their range-wide status to determine if they warrant listing as an Endangered species (L. LaClaire, personal communication).
The greatest threat to gopher frogs is the loss and alteration of both upland and wetland habitats resulting from commercial, residential, silvicultural, and agricultural development, as well as from fire suppression. Exclusion and suppression of fire from wetlands and the concomitant build-up of peat may also threaten gopher frogs by increasing water acidity past tolerance levels (Smith and Braswell, 1994). The introduction of predacious fish into gopher frog breeding ponds may render these ponds useless for successful reproduction. In areas where gopher frogs rely heavily on the burrows of gopher tortoises for refuge, tortoise declines may reduce gopher frog populations as well. The practice of removing tree stumps ("stumping") in silvicultural areas further reduces the availability of subterranean retreats.
Acknowledgments. We thank Carlos Camp, Julie Chastain, and Robert Moulis for their assistance in assembling this manuscript.
1John B. Jensen
2Stephen C. Richter
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Sep 2019.
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