Stiltgrass Bad News for Toads

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

More Feral Hog News

feral swine pigletIf you just can’t get enough feral hog news, eXtension, a network of university extension services has a resource for you: the Feral Hog Community of Practice Facebook page. This page not only has what has to be every single newspaper article published on feral hogs from across the country, also has expert tracking or trapping tips, and the occasional link to webinars and podcasts.

Visit the Feral Hog Community of Practice Facebook page here.

Photo:  A feral swine piglet. By Steve Hillebrand, courtesy US Fish and Wildlife Service

New Python Trap From APHIS

wp_c_python_trap_image006It’s got to be a really big snake to trip the trap recently patented by the US Department of Agriculture’s National Wildlife Research Center (NWRC). But that’s the point. The idea is to live trap invasive pythons in Florida while leaving the native snakes alone. One difference between the native snakes and the non-native pythons is that the pythons tend to be a lot bigger.

“Though the trap is based on a standard live trap design, the Large Reptile Trap is the first to require two trip pans to be depressed at the same time in order to close the trap door. The pans are spaced such that non-target animals are unlikely to trigger the trap,” said NWRC wildlife biologist and trap inventor John Humphrey in a USDA Animal and Plant Health Inspection Service (APHIS) press release.

The big question now is: will it work?

Read more about the trap and the invasive python problem in Florida in the Christian Science Monitor, here.Or read the APHIS press release here.

Photo: New python trap. Courtesy USDA APHIS.

Troublesome Creatures

spotted owlEfforts around the country to remove troublesome creatures — whether invasive or otherwise — have been met with a variety of reactions. In all cases the creatures are being removed because they are harming an ecosystem.

No one seems to mind that California Fish and Wildlife Department is removing South African clawed frogs from Golden Gate Park. The frogs are not native to the area, they completely destroy the habitats they invade, and they carry a fungus that is deadly to native amphibians. Read about the recovery effort in Bay Nature.

In Michigan, the Department of Natural Resources would like there to be fewer invasive mute swans. Mute swans are aggressive and don’t allow the native trumpeter swans or loons to nest. (They also have it in for ducks and geese.) Plus, they eat so many wetland plants that they can destroy wetlands. Oiling eggs has been too costly and too slow, so the department will begin to kill mute swans. Michigan Live has published several articles on the subject.
Here’s Michigan Live on why.
Here’s the plan in one county.
And here the reaction to the plan in that county.

And then there are barred owls. They’ve long been identified as a threat to northern spotted owl recovery in the Pacific Northwest. Spotted owls rely on old-growth forests. Barred owls are not so picky, and have moved into the spotted owls’ turf as the habitat has become more variable, because the old-growth forests were cut. The U.S. Fish and Wildlife Service has decided to start killing barred owls to try to improve matters for the spotted owl. The Oregonian did two stories on the situation. This one several years ago. And this one now that the program has begun.
There’s been no shortage of news coverage. See a lot of it here.

Photo: Spotted owl, courtesy US Fish and Wildlife Service

Invasive Ladybug Packs A Secret Weapon

Harmonia_axyridis01The multicolored Asian ladybug, also known as the harlequin lady beetle or ladybird (or just Harmonia axyridis), carries a fungal parasite in its blood that doesn’t seem to cause it much harm, but is deadly to the native ladybugs of Europe and North America.

That’s why the Asian ladybug has been such a ferocious competitor to native ladybugs, a paper in last week’s issue of the journal Science found. Scientists have long known that where Asian ladybugs are introduced, native ladybugs disappear, but they weren’t sure why. It seemed that the invasive species was out-competing the natives somehow. The new study explains why.

A fungus in the same genus infects honeybees.

Read the article in Science, here. (Subscription or fee required to see the entire article.)
Read the AAAS ScienceShot, here.Here’s the Guardian article, which I ignored at first because it focuses on European ladybugs. (The North American natives are in the same boat.)
Here’s the Los Angeles Times article on the same paper.

Fly away home, indeed.

Photo: ©entomart, just some of the many varieties of the multicolored Asian ladybug

How Vertebrates Invade

lizardrainbow_500x328If Junior decides that his cool new pet isn’t all that cool, and his parents decide that the best way to get rid of it is to let it go in the backyard, what are the chances that it will become an invasive species?

In a recent paper in the journal Global Ecology and Biogeography, researchers from the University of Nebraska studied both successful and unsuccessful introductions of non-indigenous vertebrate species in Florida.

For reptiles and amphibians, the biggest predictors of establishment were a small body size and a wide range in their homelands. For fish, the biggest factor was if there were other members of the fish’s genus present. Mammals became established when there were other non-native species already in the habitat. No clear pattern was detected for birds.

This research certainly doesn’t explain Florida’s python invasion, but it can provide valuable ideas for analyzing the risk of known releases or in creating importation white lists and black lists.

Read the Global Ecology and Biogeography abstract here. (Full article requires a fee or subscription.)

Photo: Rainbow lizard. Small(ish). Check. Wide range in its native land. Check. Established population in Florida. Check. Photo by Kevin M. Enge, used courtesy of the Florida Fish and Wildlife Commission.

Controlling Invasive Bullfrogs

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.