Louisiana Frog Monitoring Surveys

Monday, September 19, 2011

Natural History Notes
by Bob Thomas

Are the 28 species of Louisiana frogs doing okay? Are there as many species and individuals today as yesterday? We don’t really know the answers, but the Audubon Institute is part of an international program designed to gather information several times a year so that in the not to distant future herpetologists will have the knowledge they need to develop a management plan for our amphibian friends. Louisiana scientists, including Dr. Thomas of the Audubon Center for Research of Endangered Species, Jeff Boundy and Steve Shively of Louisiana Wildlife and Fisheries, and Jim Delahoussaye of Louisiana Department of Environmental Quality, are working together to study our frog communities.

Three times a year, amphibian scientists visit designated locations and, using a special data sheet, record the presence and population size of frog species. These data sheets are collected and tabulated by the state coordinators (Thomas, Shively, and Boundy). The information is not only maintained in our state, but it is also forwarded to the National Biological Survey in Washington, DC, to keep track of the information from all states.

Some Louisiana species are still quite abundant, including the Green Treefrog (Hyla cinerea, our state amphibian), Bird-voiced Treefrog (Hyla avivoca), Squirrel Treefrog (Hyla squirella), Cricket Frog (two species of Acris), Bull Frogs (Rana catesbeiana), Gulf Coast Toads (Bufo valliceps), Narrow-mouthed Toad (Gastrophryne carolinensis), and the like. Studies over the past two years by Dr. Thomas and his students, as well as efforts by Dr. Richard Seigel and his students at Southeastern Louisiana University, indicate that at least two species (the Dusky Crawfish Frog, Rana capito sevosa, and the Ornate Chorus Frog, Pseudacris ornata), are likely no longer in Louisiana, though they are holding their own in the southeastern U.S.

Preliminary observations and discussions among herpetologists suggest that frog populations in remote areas of Louisiana seem to be doing well. The concern is for populations that inhabit roadside ditches (exposure to runoff, exhaust fumes, pesticides) and areas that have been subjected to extreme habitat modification (clear-cuts, drainage, filling, urbanization).

You can see that someday scientists will be able to review all the information and look for trends that will tell them if any amphibian species are having difficulties and, if so, what might be done to help restore populations.

Scientists at the ACRES facilities of the Audubon Institute are playing a vital role in caring for our fabulous native frogs.