Category Archives: frogs

Stiltgrass Bad News for Toads

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northern leopard frogJapanese stiltweed is an invasive grass species that out-competes native species in wetlands, forests and other areas. Recent research at the University of Georgia found that it isn’t doing any favors for the American toad either, a post in Entomology Today reports. The paper appeared in the journal Ecology.

The stiltgrass, the researchers found, is wonderful habitat for wolf spiders. As wolf spider numbers increase, they prey on an increasing number of juvenile American toads. The researchers had noticed low toad survival in eight areas in Georgia with invasive stiltgrass and wanted to know why. They were surprised to find an abundance of wolf spiders.

The researchers hypothesize that the stiltgrass allows the spiders, which keep their own populations in check through cannibalism, to hide from each other.

Read all the gory details in the Entomology Today post.
Read all the scientific details in the Ecology paper.

In other amphibian news, National Public Radio recently featured the North American Amphibian Program, a citizen science project that has been tracking calling frogs for 20 years. The news hook seems to be that a citizen science in Virginia recently discovered the presence there of a leopard frog species that had only been identified two years ago in the New York City area.

Photo: Leopard frog. Credit: Shaula Hedwall/USFWS

NYS Creates Recovery Plan for Northern Cricket Frog

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Northern_cricket_frog_at_Neal_Smith_National_Wildlife_RefugeThe northern cricket frog is one of New York State’s two endangered amphibians. New York State law does not require recovery plans for endangered species, but the state Department of Environmental Conservation has proposed one for this species, a recent department press release says.

The plan includes conserving appropriate, but unoccupied habitat. The plan also included reintroducing frogs to unoccupied habitat, but only “if suitable habitat still remains, northern cricket frog habitat requirements are understood, and a funded and scientifically sound protocol is in place to monitor northern cricket frog abundance and assess potential causes of decline at any re-introduction site.”

In other words, more research is needed. There is a very brief paragraph about data gaps, and an even briefer one about recovery partnerships. A long list of potential tasks, includes sections on research and recovery tasks.

The comment period on the plan closes a week from today, Feb. 21, 2014.

Download the recovery plan here.
Read the NYS DEC press release about the plan here.
Read a Reptile Magazine article about the plan here.

Photo: Northern cricket frog at  Neal Smith National Wildlife Refuge in Iowa. Photo by Sara Hollerich, used courtesy US Fish and Wildlife Service.

Chytrid Fungus Found in Kansas

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Witchita chytrid frogA press release from Wichita State University says that students there have detected chytrid fungus in the frogs they tested. A previous test of five Kansas frogs did not detect chytrid fungus.

Read the Wichita State press release, here.

Pro-MED has lots of helpful technical details about chytrid fungus in its commentary about the press release, including its complex life cycle and its role in the worldwide decline of amphibians.

Read the Pro-MED comment, here.

In reading that chytrid fungus was newly found in Kansas, I found myself wishing for a map of its presence, as is available for white nose syndrome in bats and chronic wasting disease in deer. You can find that map right here.

Photo: One of the frogs tested. By: Lainie Rusco, used courtesy of Wichita State University

The Nation’s Strangest Wildlife Laws

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In Georgia, you may not keep a garter snake as a pet, but you can own a rattlesnake, says Whit Gibbons, an ecologist and environmental educator with the University of Georgia’s Savannah River Ecology Laboratory, in a column in the Aiken (Georgia) Standard.

The poisonous snake exception to Georgia’s law prohibiting the ownership of native snakes and reptiles is probably the weirdest law in Gibbons’ round-up, which includes the fact that frogs are regulated as fish in Alaska and that you may hunt frogs with a dog in Kansas. (Frogs, you know, are both funny and hard to legislate, so lots of frog laws make the list.)

I appreciate Gibbons’ list for its intelligence and wit, but I suspect that the regs he lists are not the nation’s weirdest wildlife laws. Does your state have a weird wildlife law? Do you know of one in another state? I’d love to hear about it in the comments.

Read the column here.

Frogs and Pesticides

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pacific tree frogTwo fungicides are showing up in the tissues of Pacific treefrogs, even those that live in pristine national parks, a recent paper in the journal Environmental Toxicology and Chemistry shows. The pesticides aren’t just coming from agricultural operations, but also from illegal marijuana farming.
Read the LiveScience article here.
Find the abstract for the paper here.

A study published in the journal Evolutionary Adaptations found that frogs collected from ponds where their ancestors were likely exposed to the pesticide chlorpyrifos showed greater tolerance to that pesticide themselves, perhaps showing an evolutionary adaptation to surviving exposure to that pesticide.
Read the KQED story here.
See the abstract for the paper here.

Photo: Pacific treefrog, courtesy Washington Dept. of Natural Resources

Bullfrogs Die From Fungus Too

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bullfrog OSUA recent study by researchers at Oregon State University and the University of Pittsburgh shows that bullfrogs are not just carriers of Batrachochytrium dendrobatidis, also called Bd or a chytrid fungus, but can die from it as well. The paper was published in the journal EcoHealth.

These researchers found that bullfrogs are not even a particularly good host for the fungus — although they say that this may depend on site-specific conditions.

The take-away? Scientists should keep searching for chytrid carriers, and wildlife managers in places where bullfrogs are native, should keep an eye on their populations. It wouldn’t be the first time a species was in trouble at home while being an invasive species elsewhere.

Read the Oregon State University press release here. (All other media coverage was just a reprint of the release.)

Photo: by Megan Cook, courtesy of Oregon State University

Pesticides Harm Frogs

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Rana_temporaria_LC0183If you take frogs and spray them with some of the fungicides, insecticides and herbicides most commonly sprayed on crops, they will die. That is the conclusion of a recent paper by German and Swiss researchers in the journal Scientific Reports that received some notice in the European media.

A brief read-through suggests that the researchers stuck three frogs in a bucket then sprayed them with a pesticide.

Needless to say, the pesticide manufacturers, object, saying that the tested conditions are worse than what happens in real life, an article in The Guardian (a British newspaper) reports. The researchers counter in the Guardian article that when multiple applications of the pesticides wash into nearby bodies of water, it’s equivalent to at least one of the test conditions, were a 10 percent solution of the chemicals were used.

Read The Guardian article here.
Read an article in Agence France-Presse (AFP)

This news is interesting, although I have qualms about the methodology (not the direct spraying or even the bucket, but that according to the AFP article only three frogs were used for each test), but the journal, Scientific Reports, is interesting as well. It’s an open-access journal from Nature Publishing. Researchers pay to play. The journal promises on its website that once payment is received, the paper will be published promptly. It also promises at least one peer reviewer.

Read the whole paper here and see what you think, because, you know, it’s open access.

Photo: European common frog, the species in the study, in Germany. Photo by Jörg Hempel, used under Creative Commons license.

Controlling Invasive Bullfrogs

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bullfrogIn the Pacific Northwest, it is not unusual to try to kill off invasive bullfrogs by drawing down managed wetlands in imitation of ephemeral wetlands, a paper in The Journal of Wildlife Management says. Because the bullfrogs over-winter as tadpoles, the idea is to remove that over-wintering habitat.

However, the paper notes, in Oregon’s Willamette Valley, bullfrogs were observed metamorphosing after just four months. Some frogs can speed up their metamorphosis in response to a wetland that is drying out, can bullfrogs do this as well? If they could, this would be bad news for the invasive species control technique.

The study took bullfrog tadpoles from both ephemeral and permanent wetlands and subjected them to various regimes of water and lack of water. The study found that the bullfrog tadpoles did not speed up their metamorphosis in response to drying wetlands, but they did show a lot of variety in how long they took to mature.

The paper concluded that drawing down managed wetlands won’t cause bullfrog tadpoles to metamorphose faster, but that some bullfrogs may survive the draw-down because of the natural variability in the amount of time it takes them to become frogs.

Find the Journal of Wildlife Management article here. Reading it requires a fee or a subscription.

Crayfish Can Spread Chytrid Fungus

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crayfishA study by University of South Florida scientists, published online ahead of publication in the Proceedings of the National Academy of Sciences found that crayfish are capable of being infected by Batrachochytrium dendrobatidis, a chytrid fungus implicated in a worldwide amphibian die-off. Further, the study found a positive correlation between the presence of crayfish in Colorado wetlands and chytrid infections in amphibians.

Read the PNAS abstract here, in PubMed. (Reading the paper itself requires a subscription or fee.)

There is a summary of the finding on Smithsonian.com. Read it here. It was that article that attracted the attention of ProMED, which also published a fairly interesting comment. (Read that here.)

Photo: A crayfish in the family Astacidae, which does not include the crayfish species mentioned in the paper, but come on, it’s a crayfish. By Eric Engbretson, courtesy of the US Fish and Wildlife Service.

Back in September we mentioned a paper in The Southwestern Naturalist that found a correlation between chytrid infection in amphibians and the presence of bullfrogs and crayfish in wetlands in Mexico. (Personally, I would have bet on the bullfrogs, which have been found to be resistant to chytrid, but both are invasive in the area studied.)

 

Turtles, Cougars, and Frogs in the Southwest

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The current issue of Southwestern Naturalist has several articles that may be of interest to biologists outside of the region.

Yellow mud turtles decline in the Midwest. The largest populations of yellow mud turtles in Iowa, Illinois, and Missouri have experienced severe declines. Withdrawal of water from aquifers is the main cause, but the growth of woody plants also plays a role. Read the article, here. (Requires fee or subscription for full article.)
More info on yellow mud turtles from Texas Parks and Wildlife, here.

Cougar habitat in Texas and northern Mexico. Researchers from Sul Ross State University tested a model of current and potential cougar (Puma concolor) in Texas and northern Mexico and found that it worked. Read the article here. (Same for fees or subscription.)

Fungus strikes desert frogs. Chytrid fungus was found in desert oasis frog populations in Baja California Sur. The oases with higher infection rates also had bullfrogs and non-native crayfish. Read the article here.

Also interesting: Western red bats (Lasiurus blossevillii) and Arizona myotis (Myotis occultus) were found on the lower Arizona River after the area was restored. The Arizona myotis had been extirpated from the area, and the western red bat had not be found there previously. Read the article here.