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Science Seeks to Stem Snake Surge

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Right now in Florida, non-native, giant constrictor snakes—pythons, anacondas, and the boa constrictor—are being found in the wild, and two species have established several breeding populations. The snakes pose a considerable resource management challenge for agencies charged with preserving native ecosystems and species. USGS research wildlife biologist Bob Reed discusses how scientific research can help us find ways to understand, manage, and control these introduced predator snakes.




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Juliette Wilson: Hello and welcome to the USGS CoreCast. I'm Juliette Wilson at the Fort Collins Science Center in Colorado. Right now in Florida, giant constrictor snakes--pythons, anacondas, and the boa constrictor--are rapidly becoming a giant problem. The snakes pose a considerable resource management challenge for federal and state agencies charged with preserving native ecosystems and protecting threatened and endangered species.

To help explain how science can help address management questions, I turn now to Dr. Bob Reed, a herpetologist and research scientist with the USGS Fort Collins Science Center. He and his colleague, Dr. Gordon Rodda, just finished a risk assessment for the US ecosystems and people concerning these invasive giant constrictor snakes.

Welcome, Bob, and thanks for being here today.

Bob Reed: It's nice to be with you.

Juliette Wilson: First of all, let's look at the big picture. Invasive species, what makes a species invasive and why are they such a problem?


Bob Reed: Well, an invasive species is a non-native species that has some sort of negative impact when it's introduced to a novel environment. Obviously, not all non-native species are invasive. For example, most of our crops and domestic animals are actually non-native in the United States, but they help us so we don't consider them to be invasive.

However, depending on the species you're talking about, negative impacts of invasive species can be ecological, economic and, in some cases, even societal.

Juliette Wilson: You have extensive experience in working with reptiles in general and snakes in particular. What do you see as the biggest problems related to an invasive species that happens to be a snake?

Bob Reed: In most cases of invasive snakes worldwide, they pose a threat as predators on a native species. And this has been shown over and over again where you have species that are introduced to an area that maybe doesn't that kind of predatory snake. In some cases, it doesn't have any kind of snake whatsoever. And because of that, the native animals have no any evolutionary history with the kind of predator that snakes represent.


In a controlled context, the biggest problem with invasive snakes is that they have low detection probabilities. And by this, I mean that they are very secretive. Humans don't encounter them very often. They may not move very often and that means, they don't come in contact with traps or other control tools. And they're generally a difficult species to control.

Juliette Wilson: We mentioned in the introduction that you had just completed with your colleague, Dr. Gordon Rodda, a risk assessment on giant constrictors should they become established in the United States. What led the US Fish and Wildlife Service and the National Park Service to ask you to conduct that risk assessment?

Bob Reed: The US Fish and Wildlife Service is the regulatory arm of the Department of the Interior. And so they're responsible for coming up with policies and regulations that might help to prevent the establishment of invasive species or mitigate their impact once they are established.


And they have been dealing with the question of invasive snakes for quite a while but, unfortunately, they had no compendium of biological information on all of these giant snakes.

So our goals were two-fold. First, to pool together all the available information on these species and then, to conduct a formal risk assessment that would tell us how these species fall out relative to each other in terms of the risks that they pose to US ecosystems and the economy of the US.

The biological information can be used by the Park Service and other management authorities to help understand the ecology of the snakes. And that's vital to planning any sort of control program or management program.

Juliette Wilson: Do you think it's possible to control the spread of the different species?

04:01Bob Reed: The prospect of eradication of widespread species of snakes is fairly unlikely given available resources. At some point, we might be able to develop tools that would allow that.

But in the meantime, invasive species research, especially for invasive reptiles falls into two main categories. The first is risk assessment, can we predict which species will most likely be problematic? And then the second, can we use local control to protect really vital resources?

For example, we're managing a project on Key Largo, on the Northern Florida Keys, to interdict snakes as they arrive from the mainland. There have been several Burmese pythons that have shown up in Key Largo in the last couple of years.

So we have an extensive trapping program. That trapping program is to protect the federally endangered Key Largo wood rat. It's also to serve as a barrier to pythons expanding to the Southern Florida Keys which contain a variety of endangered species.

05:00Juliette Wilson: Well, what can ordinary citizens do to prevent invasions of exotic or non-native species? Are there any outreach efforts you've been able to make, or what kinds of activities are going on?

Bob Reed: There are numerous outreach and education efforts in South Florida and nationwide right now. In the US, there are multiple efforts, including those from the pet industry and the nature conservancy and many state and local and federal agencies.

They're focused on educating people, what to do if they see an invasive snake, what to do if they have a pet animal that they no longer want to care for, how to provide adequate caging to prevent escapes, and many other outreach and education efforts.

The biggest problem with giant snakes in particular is that they're usually sold as hatchlings. And for many people, the prospect of owning a giant snake is very attractive before you have to deal with the actual logistics of owning a giant snake.

06:01When the animal's only 20 inches long and it can live in a 20-gallon aquarium, things are very easy. But when you have to provide a very large facility for housing it, you've got to spend a lot of money on large prey items such as rabbits and you've got to start cleaning up after those critters, for many people, the attraction wears off quickly.

Juliette Wilson: Well, Bob, thank you so much for being here today.

Bob Reed: It was nice to be here with you.

Juliette Wilson: For more information on giant constrictor snake research, we invite listeners to visit where you will find pictures and links to other sites with related information about giant constrictor snakes.

CoreCast is a product of the US Geological Survey, Department of the Interior.

Announcer: Juliette Wilson is an information specialist with the ASRC Management Services, under contract to the USGS.

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