Absolutely Fabulous Frogs
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American Bullfrog in South Dakota
American Bullfrog in South Dakota.
Visuals Unlimited/ Natu

On Nature Fabulous Frogs, airing this month on SDPB1, you’ll learn from delightfully perspicacious David Attenborough about some of the over 5,000 species of frogs and toads inhabiting Earth. A sincere frog fan, the revered British naturalist kept a European tree frog as a childhood pet and was thrilled when scientists recently named a newly discovered Peruvian rubber frog Pristimantis attenboroughi after the famed broadcaster.

In South Dakota, our own crown prince of frogs may be Jake Kerby, associate professor of biology at USD and one of the state’s only amphibian experts. Kerby says he fell in love with amphibian research 20 years ago as an undergraduate in his home state of California because studying the cold-blooded vertebrates “answers interesting ecological questions” that hold wider implications. “The primary thing about amphibians is, in terms of animals with backbones, they are the most threatened class of animals on the planet,” says Kerby. “About a third are at-risk for extinction. Climate change, invasive species, contaminants, and habitat destruction are probably affecting frogs more than other animals, so they’re a good focal system.”

A self-described “defender of amphibians,” Kerby leads students in research across the state to zero in on what’s harming South Dakota’s frog populations. “In places like South Dakota, massive wetland losses cause habitat loss and habitat degradation that harm local frog populations.” Kerby and his researchers recently concluded a four-year project researching the impact of agricultural tile drain systems, or subsurface drainage, on federally and state-protected wetlands typically set aside to grow waterfowl populations for hunting. Partnering with the state’s Department of Fish and Wildlife Service, Kerby says researchers “see really high levels of contaminants in the outfalls of the tile drains getting into our wetland systems.” The contaminants include nitrates from fertilizers, neonichotinoids from corn and soybean seed pre-coated with insecticides, and selenium, a naturally occurring soil mineral that Kerby says may be disturbed when tile drain pipes are installed, then gets carried into wetlands.

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Kerby’s research team found these contaminants are not only impacting tadpoles, they are decreasing quantities of frog food; specifically, the populations of aquatic insects – midges, beetles, damselflies, dobsonflies and others – eaten by adult frogs and other species. “And while I love amphibians,” says Kerby, “it should be noted ducklings, bats and other animals feed the same way as amphibians, so this is affecting entire ecosystems.”

Kerby understands how tile drain systems and pre-coated seeds benefit growers. He and his students interact with farmers frequently out in the field, accessing farm ponds and conducting interviews about pesticide use. He hopes that publishing his group’s findings in scientific literature, working with groups like Ducks Unlimited and water research boards, and partnering with farming experts can lead to addressing issues like soil health to emphasize biological solutions over chemical ones. “The goal is that we can create soils with naturally occurring bacteria that can do the work farmers need and can create better soils that can infiltrate the water and do, in effect, the job of tile drains without the cost of installing and maintaining these systems, and do it in an environmentally friendly kind of way,” says Kerby.

Another key to conserving frog populations is enlisting South Dakotans as fellow amphibian defenders. As the state’s only frog biologist, Kerby says he can’t study all the region’s 13 frog species. To recruit citizen scientists who can contribute vital herpetology data from far afield, Kerby encourages downloading the HerpMapper app onto phones to photograph and record the GPS location of our state’s frogs, salamanders, lizards, and snakes. Kerby and colleagues also maintain the Amphibians and Reptiles of South Dakota Facebook page, as well as a website, SDHerps.org.

Kerby says the overall health of South Dakota frog populations are, literally, all over the map, a chief reason citizen scientists are needed. “In some places frog populations are robust,” says Kerby. “But in other places where there are high levels of contaminants, the Ranavirus is causing a higher number of die offs. Another example is, just south of USD, the cricket frogs are gone. It’s a somewhat natural location, no huge development, so what’s going on? There are lots of questions and we don’t yet have answers.”

To help track South Dakota’s frogs, get the HerpMapper app at HerpMapper.org.

For more information on South Dakota’s amphibians and reptiles, see SDHerps.org.

Nature Fabulous Frogs

SDPB1: Wednesday, June 13, 7pm (6 MT)

SDPB2: Sunday, June 17, 7pm & 11pm
(6 & 10 MT)