| Mississippi Gopher Frog | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Amphibia |
| Order: | Anura |
| Family: | Ranidae |
| Genus: | Rana |
| Species: | R. sevosa |
| Binomial name | |
| Rana sevosa Goin & Netting, 1940 |
|
| Synonyms | |
|
Lithobates sevosus |
|
The Mississippi gopher frog (Rana sevosa) or dusky gopher frog is a rare species of true frog. It is endemic to the southern United States, and its natural habitats are temperate, coastal forests and intermittent freshwater marshes. This secretive frog is on average 3 inches (8 cm) long, with a dark brown or black dorsal surface covered in warts.
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The Mississippi gopher frog was originally described as a new species (Rana sevosa) by Coleman J. Goin and M. Graham Netting in 1940. Subsequently it was considered one of several subspecies of the more widespread and common gopher frog (Rana capito). It was re-elevated to species status in 2001. [1]
The Mississippi gopher frog was once abundant along the Gulf coastal plain in lower Louisiana, Mississippi, and Alabama—from east of the Mississippi River Delta to the Mobile Bay.[2] However, it has not been seen in Alabama since 1922 or in Louisiana since 1967. Presently, the population is approximately 100 frogs found in only one body of water (Glen's Pond) in Harrison County, Mississippi and possibly several other locations in Jackson County, Mississippi.
The Mississippi gopher frog is a mid-sized, stocky, frog whose total body length is about 3 inches (8 cm). The frog’s back ranges in color from black to brown or gray and is covered with dark spots and warts. The male's call has been compared to the sound of human snoring. Another notable feature of this secretive frog is that when exposed to bright light or threatened, the frog will put its hands in front of its face to shield its eyes.[2] Other defense responses include inflating its body and secretion of a bitter, milky fluid from warty glands located on its back. Maximum longevity of the frog is 6 to 10 years.
The diet of adult frogs probably includes frogs, toads, insects, spiders, and earthworms. Males reach sexual maturity at 4 to 6 months and females at 2 to 3 years. The fist-sized egg masses, containing 2,000 or more eggs, are typically attached to stems of emergent vegetation. Tadpoles average slightly over 1 inch long (3 cm) and require 80 to 180 days to complete metamorphosis in the field.[2]
The Mississippi gopher frog’s habitat includes both upland, sandy areas covered with an open longleaf pine forest with abundant ground cover; and isolated, temporary, wetland breeding sites within the forested landscape.[3] Adult frogs spend most of their lives in or near underground refuges in uplands. They often use both active and abandoned gopher tortoise burrows; they also use abandoned mammal burrows, stump and root holes, and possibly crayfish burrows.
Breeding sites are isolated, grassy ponds that dry out completely at certain times of the year; their seasonal nature prevents establishment of a fish population, which would endanger tadpoles. Substantial winter rains are needed to ensure that the ponds are filled sufficiently to allow development of juvenile frogs. The timing and frequency of rainfall is critical to the successful reproduction of the Mississippi gopher frog. Adults frogs move to breeding sites in association with heavy rains during winter and spring (December to April). Tadpoles must complete their metamorphosis before the ponds dry in the early summer.
The Mississippi gopher frog was listed as endangered by the State of Mississippi in 1992 and by the U.S. Fish and Wildlife Service in 2001.[4] There is only one known remaining population of the Mississippi gopher frog. It consists of approximately 100 adult frogs known from one site in Harrison County, Mississippi (Glen's Pond). Several possible sites are located in Jackson County, Mississippi. The Mississippi gopher frog is regarded as rarest amphibian in North America.[5]
Adults face every-day threats from a wide assortment of possible predators, including birds, mammals, and reptiles. Tadpoles face predation from fish, aquatic insects, birds, turtles, and snakes. Chytridiomycosis caused by chytrid fungus, an infectious disease of amphibians, has had a detrimental affect on Mississippi gopher frog populations.[1]
The historic regional decline of the species has been related to loss of open longleaf pine habitat needed for subsistence and the seasonal ponds needed for reproduction.[6] Implementation of fire suppression in the 1930s was a factor, because frequent fires are necessary to maintain suitable open canopy and ground cover vegetation of the aquatic and terrestrial habitats. Reduced Gopher Tortoise populations may also be a factor of the frog's demise.
Other natural processes—such as genetic isolation, inbreeding, droughts, and floods—pose ongoing threats to the existing population. In addition, a host of immediate anthropogenic threats confront the only remaining breeding pond of the frog: a proposed residential development, new and expanded highways, and a proposed reservoir. The main threats posed by these projects are local changes in hydrology, the need for fire suppression, and habitat destruction and fragmentation. Other concerns include possible sedimentation and run-off of toxic chemicals that may injure or kill tadpoles and adult frogs.
A Gopher Frog Recovery Team oversees conservation strategies that include pond water supplementation in dry years, habitat management, assisting tadpole survivorship, captive rearing, construction of alternative-breeding ponds, and treating infected tadpoles.[3] This program needs to be continued and expanded. Surveys are needed to check the status of the recently discovered populations, and to determine whether or not the species survives elsewhere. The recovery effort was greatly enhanced in 2007 by the donation of "Mike's Pond" to the Nature Conversancy.[7].
The U.S. Fish and Wildlife Service has been working with the U.S. Forest Service to protect the last remaining Mississippi gopher frog population.[3] Both agencies have joined forces to rehabilitate a nearby pond as a future breeding site. The Fish and Wildlife Service, in conjunction with gopher frog researchers, has developed a strategy to introduce egg masses into this pond and to determine if the eggs can successfully develop into juvenile frogs at the site. Maintenance of open longleaf pine-dominated uplands and seasonal wetlands through growing season prescribed burning is the most appropriate form of management. This management strategy also favors gopher tortoises as well. Mechanical site preparation, as well as stump removal, should be avoided in forestry operations. Obviously, all known and potential breeding sites should be protected.
Five zoos (New Orleans, Memphis, Detroit, Miami, and Omaha) have 75 Mississippi gopher frogs in captivity, and are conducting ongoing artificial breeding programs.[8]