Monday, December 9, 2013

Kingsnakes Keep Copperheads in Check **Special Blog Carnival Edition - Don't Miss Links at Bottom**


 "We just found one of our Kingsnakes doing something really cool." 

    It was 2006 and we had recently started radio-tracking about a dozen Kingsnakes (Lampropeltis getula) in a big chunk of longleaf pine forest in southwestern Georgia. Kingsnakes were fascinating to me because they were a big, recognizable species for which we knew next to nothing. In fact, this was one of the first radio-tracking studies conducted on the species. Almost anything we documented would be new to science, so when the two field techs working on the project came into my office to report on what they had observed that day, I was ready to be surprised.

    Radio-telemetry is an exciting research tool because it allows you to spend a day in the life of the animal you are tracking. You can find out where the animal sleeps, swims, rests and how it finds its food. These insights are particularly treasured by snake biologists like myself because snakes are so secretive; it is almost impossible to observe them without radio-telemetry but a lot of work goes into catching snakes, implanting them with radio-transmitters, and then tracking the snakes in the field.

This is me assisting on a Kingsnake
 surgery, we don't mess around.
    Kingsnakes are perhaps most famous for their habit of eating other snakes and our study animals did not disappoint. As you can see from the picture above, we lucked out and got to observe one of our Kingsnakes chowing down on a Copperhead (Agkistrodon contortrix). Not only was this incredibly cool to see, but it was also reassuring to know that our animals could easily return to their regular routines after going through the transmitter-implantation surgery.

    Fast forward a few years and I am a Ph.D. student at Auburn University. Our Kingsnake study had produced a couple papers related to how much land the animals use as well as the habitats they preferred, this information can now be used to help figure out what Kingsnakes might need to survive in a particular area. This was particularly important to know because people had started to notice that Kingsnake populations across the southeastern United States had started to decline and even disappear. And, nobody knew why. Although our Kingsnake studies were interesting and novel, they didn't help us figure out why Kingsnake populations were blinking out other than to rule out habitat change as a likely cause of these declines.

    In any case, one of the areas where Kingsnake declines were the most dramatic was Conecuh National Forest, Alabama, a forest that my new Auburn colleagues had spent a lot of time exploring. When the renowned Auburn herpetologist/professor Dr. Robert Mount had surveyed Conecuh in the 1970s and 1980s, he reported Kingsnakes as one of the most commonly encountered species. However, none had been reported for years by the time I arrived in Alabama. 

    Fascinatingly, while Kingsnakes were apparently disappearing over the last few decades, another species was becoming more and more common. Dr. Mount had reported Copperheads to be a rare species but today they are far and away the most commonly observed snake. For biologists that knew about the Kingsnake's taste for Copperheads, the appeal of generating a convenient hypothesis proved irresistible. Soon an idea started popping up frequently in conversation and also in the newspapers: Kingsnakes are predators of Copperheads, so Copperheads are becoming more common because Kingsnakes are disappearing.


    I was skeptical. There was no question that Kingsnakes loved to eat Copperheads, at least they did so frequently. And, the population trends for the two species over the last thirty years in Conecuh National Forest sure seemed to suggest something could have been going on between them. But it still seemed fishy to me. The numbers of Copperheads and Kingsnakes could be changing due to something completely unrelated to each other, like habitat change. Furthermore, snakes weren't really known to dramatically influence prey populations, particularly when that prey is another species of snake. So, I set out to prove everybody wrong.

    Due to a few ongoing collaborations I was involved in, I had access to a giant database of snake observations from across the southeastern United States, from North Carolina down to Florida and west to eastern Texas. All these data were from traps and the traps were located in areas where Kingsnakes were still abundant, where they had disappeared, and everything in between. I predicted that if Kingsnakes truly had an ability to influence the size of Copperhead populations, we would see a negative relationship between their numbers. Specifically, if Kingsnakes controlled Copperhead abundances, we would expect to see lots of Copperheads in areas where there were few Kingsnakes and few Copperheads in areas where there were lots of Kingsnakes. Critically, we were able to characterize the habitat surrounding each of these traps and control for it in our analyses. I was confident that we would find no relationship between the abundances of Kingsnakes and Copperheads once we examined trends at many different sites instead of just focusing on Conecuh National Forest. I looked forward to taking the results and rubbing them in the faces of all my friends while yelling, "This is what you get for not using good data to generate your scientific hypotheses!"

    I never got the chance. 

    To my surprise, we revealed a clear, negative relationship between the abundances of Kingsnakes and Copperheads, actually supporting the hypothesis that everyone was already talking about. So, I had to change my mind. We still can't prove that Kingsnakes lower the abundances of Copperheads, but the best available data sure seem to suggest this is the case. If true, the implications are clear. First, snakes can be important predators in their ecosystems with the potential to influence populations of their prey. Second, the mysterious Kingsnake declines that are occurring in the southeastern United States could end up having surprising effects on other species. Finally, and perhaps ironically, if people do not want to have a lot of venomous Copperheads in their yards, they should become champions of snake conservation!



***   I want to bring up one last point. Many people already know that Kingsnakes eat Copperheads and some folks even catch Kingsnakes wherever they are found and release them into their yards hoping that all the Copperheads will be eaten. I don't think that's a good idea. First of all, if your yard was good habitat for Kingsnakes, they would be there already. If you drop off a Kingsnake in a spot that isn't a good habitat for that species, it will probably wander off and/or die (I covered this when discussing how to relocate rattlesnakes away from your yard). Second of all, moving a strange Kingsnake to your property could actually be bad for the Kingsnakes already there, because the new animal could introduce a disease they aren't used to. Finally, moving snakes around, especially if they have been held in captivity, might even be illegal in your state. The best way to keep Copperheads away from your house is to make your yard unappealing to snakes.

Photos appear courtesy of Aubrey Heupel and Benjamin McDaniel.

Related Scientific Articles

Steen, D.A., & et al. (in press). Copperheads are abundant where kingsnakes are not: relationships between the abundances of a predator and one of their prey Herpetologica

Steen, D.A., Linehan, J.M., & Smith, L.L. (2010). Multiscale habitat selection and refuge use of common kingsnakes, Lampropeltis getula, in southwestern Georgia Copeia, 2010, 227-231 DOI: 10.1643/CE-09-092

C.T. Winne, & et al. (2007). Enigmatic decline of a protected population of eastern kingsnakes, Lampropeltis getula, in South Carolina Copeia, 2007, 507-519 DOI: 10.1643/0045-8511(2007)2007[507:EDOAPP]2.0.CO;2

Finally:

    Social media has become an important tool in conducting effective science education and outreach. A few other bloggers and myself have decided to bring attention to a network of students, naturalists, and professionals that use social media to communicate information about amphibian and reptile natural history, science, and conservation.

    Our inaugural event is inspired by Partner in Amphibian and Reptile Conservation’s (PARC) Year of the Snake. Today we all published blog posts about the diversity of ecosystem services provided by snakes. We encourage everyone to follow us on Twitter, visit all of our blogs, and help spread the word about our outreach event, we hope the first of many touching on different themes related to the importance of amphibians and reptiles.

Check 'em out!

Life is Short But Snakes are Long: Ecology of Snake Sheds by Andrew Durso @am_durso

Living Alongside Wildlife: Kingsnakes Keep Copperheads in Check by David Steen @AlongsideWild

Nature Afield: Pythons as Model Organisms by Heidi Smith @HeidiKayDeidl


The Traveling Taxonomist: Snakes of Madagascar: Cultural and Ecological Roles by Mark Scherz @MarkScherz

Social Snakes: Good Neighbors Make a Greater Impact by Melissa Amarello @SocialSnakes

Strike, Rattle, and Roll: Snakes and the Ecology of Fear by Bree Putman @breeput

Australian Museum: When the Frogs Go, the Snakes Follow by Jodi Rowley @jodirowley

SnakeBytes TV: The Brown Tree Snakes of Guam by Brian Barczyk @SnakeBytesTV

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