Endangered Dusky Gopher Frog

By Megan Molloy

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Description and Ecology of Dusky Gopher Frog

The dusky gopher frog (Rana sevosa) is an r-selected amphibian who is currently one of the top 100 most endangered species in the world. Adult dusky gopher frogs have a stubby appearance due to a plump body, relatively short legs, and a large head. They are densely packed with warts and come in a wide range of brown and gray colors. These amphibians live a complex life cycle; going from aquatic eggs/larvae to terrestrial adults.  

Adult dusky gopher frogs spend a majority of their lives underground in forested habitats. Dusky gopher frogs are endemic of the longleaf pine (Pinus palustris) ecosystem. They leave their habitat during breeding season (typically December-March); migrating to isolated ephemeral (seasonally flooded) wetlands to lay eggs. Tadpoles spend at least 94 days in the pond developing, then they undergo metamorphosis. Age at maturity is 6–8 months for males and 24–36 months for females. They typically live for about 7 years. The dusky gopher frogs’ carnivorous diet consists of frogs, toads, small mammals, beetles, hemipterans, grasshoppers, spiders, roaches, and earthworms.

Geographic and Population Changes

Ponds where dusky gopher frogs reside.

         Historic records for the dusky gopher frog exist for sites in Mississippi, Alabama and Louisiana. Numerous surveys have been conducted in these states, concluding that there is no continued existence of the dusky gopher frog in Alabama or Louisiana. Only one population in Mississippi was known at the time of listing (2001). Since 2005, two more populations have been discovered in Harrison and Jackson Counties, Mississippi. An additional population was established in Jackson County Mississippi with translocation. Only one of these populations is considered stable at this time. Surveys have established that there are a minimum of 135 individual adult frogs remaining in the wild.

Listing Details

Critical habitats of the dusky gopher frog.

On December 4, 2001, The U.S. Fish and Wildlife Service (USFWS) listed the Mississippi gopher frog (Rana capito sevosa) under the Endangered Species Act (Act), without critical habitat, as an endangered distinct vertebrate population segment (DPS) of the gopher frog (Rana capito). On June 12, 2012, USFWS published a final rule designating critical habitat for dusky gopher frog and changing its status to “species” and its name to the dusky gopher frog (Rana sevosa). Approximately 6,477 acres (ac) in Louisiana and Mississippi have been designated as critical habitat for the dusky gopher frog. The frog cannot be killed or removed from the wild without a permit in Alabama, Louisiana and Mississippi.  The dusky gopher frog has a recovery priority number of 5, indicating that the species faces a high degree of threat and has a low recovery potential.

Cause of Listing and Main Threats to Its Continued Existence

The dusky gopher frog faces a number of persisting threats. Habitat degradation was the primary factor in the loss of historical dusky gopher frog populations. The areas where the frog currently resides are under protection, but potential translocation sites continue to be destroyed. Residential and commercial development continue to degrade the longleaf pine ecosystem that dusky gopher frogs require. Potential habitat is also affected by dumping into or filling ponds and conversion of wetlands to fish ponds or farm ponds for domestic animal grazing. Habitats and paths used by the dusky gopher frog may be fragmented by roads. This results in the direct death of frogs when they attempt to cross the roads. Within a metapopulation, connectivity to local populations is important for gene flow. The dusky gopher frog also needs to be able to migrate during breeding season. Habitat fragmentation makes both of these functions challenging.

The dusky gopher frog also faces the threat of pesticides and herbicides commonly used in habitat management. The frog has very permeable eggs and skin which absorb harmful substances from the environment. Negative effects of common pesticides and herbicides include delayed metamorphosis, paralysis, reduced growth rates, and mortality.  

Due to the dusky gopher frogs small population size, catastrophic events such as a disease outbreak may be devastating. In 2003, a lethal disease (unnamed) killed a majority of the dusky gopher frogs at the largest population site. The disease still exists but has never been as bad as the first occurrence. The disease has recently been affecting the eggs and larvae of the dusky gopher frog, but not the adults. Accordingly, scientists have been removing eggs from each breeding site and raising them in the lab until maturity.

The dusky gopher frog is also affected by alteration of hydrological patterns due to urbanization and climate change; predation; and plant community changes as a result of invasive species such as cogongrass (Imperata cylindrica) and tallow tree (Triadica sebifera).

Description of Recovery Plan

Water tanks used to raise dusky gopher frog tadpoles to metamorphosis. 

There is currently a recovery plan set up for the dusky gopher frog. These are the actions that need to be taken;

1. Monitor the wellbeing of existing populations.

2. 

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   Maintain and improve existing populations through habitat restoration and management. Habitat will be maintained by minimizing soil disturbance and native herbaceous groundcover vegetation loss; maintaining open canopied, grassy wetlands; and restoring degraded upland habitats.
3. Search for additional dusky gopher frog populations and potential habitats. Searches are being conducted in Mississippi and Louisiana.
4. Establish new populations through translocation and reintroduction.
5. Conduct a population and habitat viability analysis (PHVA) and develop the necessary supporting research.
6. Create and implement guidelines for the use of translocation to establish dusky gopher frog populations.
7. Update and implement a controlled propagation and reintroduction plan to facilitate using captive dusky gopher frogs in translocation efforts.
8. Create and distribute public educational and informational materials/programs to advertise and promote volunteer work.

The immediate objective of this recovery plan is to prevent the dusky gopher frog from going extinct. The long-term objective is to move the species from endangered to threatened, however, it is likely that the frog will never be delisted altogether. The estimated cost of recovery for a 5-year period of recovery effort is $3,615,00. Land that has been determined as essential to the dusky gopher frogs survival has been designated as critical and is under protection. Twelve critical habitat units have been established and thirteen ponds have been restored or created.

What Can You Do?

• Volunteer with the U.S. Fish and Wildlife Service https://www.volunteer.gov
• Donate to U.S. Fish and Wildlife Service https://www.fws.gov/international/wildlife-without-borders/donations.html
• Prevent climate change by reducing your meat and dairy consumption and carpooling. 
• Don't disturb protected wildlife areas!

Work Cited

AmphibiaWeb. 2016. <http://amphibiaweb.org> University of California, Berkeley, CA, 

       USA. Accessed 2 Dec 2016.

"Mississippi Species." The Nature Conservancy. N.p., n.d. Web. 25 Nov. 2016. 

Stephen C. Richter and Richard A. Seigel (2002) Annual Variation in the Population Ecology 

       of the Endangered Gopher Frog, Rana sevosa Goin and Netting. Copeia: December 

       2002, Vol. 2002, No. 4, pp. 962-972.

U.S. Fish and Wildlife Service. 2015. Dusky Gopher Frog (Rana sevosa) Recovery Plan.
       Atlanta, Georgia. 86 pp. 

U.S. Fish and Wildlife Service. 2012. Endangered and threatened wildlife and plants; 
        designation of critical habitat for dusky gopher frog (previously Mississippi gopher 
        frog). Federal Register 77:35118-35161.