Wildlife Services on Tackling Invasive Snakes, Teaching Geese to Dodge Planes

By Joshua Rapp Learn

Brown tree snake. Image Credit: U.S. Department of Agriculture, licensed by cc 2.0

Wildlife professionals need to have a host of tricks up their sleeves to limit human-wildlife conflicts. In the case of the U.S. Department of Agriculture’s Wildlife Services Agency, these tricks include mouse butter to trick invasive brown tree snakes (Boiga irregularis) into ingesting poison and finding techniques to make Canada geese (Branta canadensis) believe airplanes are predators.

Brown tree snakes are an invasive species affecting Guam, Hawaii, and other places. One of the easiest ways to eradicate them is through a single dose of Tylenol, which is enough to kill a snake. But the trick is all in the delivery.

“Most snakes are very good scavengers,” said Travis DeVault, a Wildlife Services field station and project leader at the National Wildlife Research Center. DeVault Monday spoke at a TWS annual conference featured session, “The Latest in Wildlife Services Research.”

Unfortunately, having to use a dead mouse to poison every brown tree snake can add up in costs. But DeVault said that Wildlife Services researchers are developing a “mouse butter” that has the scent of mice but is mostly made up of cheaper material such as canned meat. “When you put the mouse butter on the meat, it approaches the effectiveness of the dead mouse. This is what we’re looking for,” he said. “Dead mice are the current gold standard.”

DeVault also worked on science that attempts to make airplanes scarier to Canada geese — and, subsequently, safer — in an attempt to protect both the geese that are often killed by airplane strikes and the airplanes that can be damaged by them during takeoff and landing.

There is some evidence that geese sense that airplanes are bad for their survival — necropsies on geese that were hit by airplanes at the JFK Airport in New York show that many of them were taking evasive maneuvers similar to the way they react with other living predators in their last moments. But the trouble, DeVault said, was that geese may not be aware of the danger until the last moment, when it’s too late.

“From that bird’s perspective, that aircraft never chases them, never acts like a predator,” he said.

In an effort to determine if there are ways to clue these birds in about the approaching danger to airplanes, or indeed to any approaching vehicle, Wildlife Services is carrying out tests that involve the use of videos of approaching birds and vehicles to see how they react.

A Rat-Free Island Future

Larry Clark, the director of the National Wildlife Research Center, spoke at the session about efforts to remove invasive rodents like Norway rats (Rattus norvegicus), whose destructive habits can restructure entire island ecosystems.

In Rat Island, Alaska, for instance, researchers used poison to destroy the rats, however, that meant the collateral killing of some bald eagles in the area. Still, after the rats were gone, the Pisonia forest on the island regenerated and two indigenous species of snail thought to be extinct there reappeared soon after.

“The issue it gets to is how can we responsibly do these things?” Clark said.

Wildlife Services is a Strategic Partner of TWS.

Joshua LearnJoshua Rapp Learn is a science writer at The Wildlife Society.

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