Success! Finding Indigos in Florida

Views:

84 views

Authored by: Javan Bauder

Searching in an abandoned orange grove. - Javan Bauder
When I started working on Eastern Indigo Snakes in Highlands County, Florida, I knew that finding indigo snakes would not come easily. The consensus from people who have looked for or studied indigos in Florida is that indigo snakes are difficult to survey for in peninsular Florida, even in areas where are doing relatively well. Part of this difficulty stems from the tendency of indigo snakes in peninsular Florida to use a variety of shelter sites and habitats throughout the year, so indigo snakes can be almost anywhere any time of the year.
 

Indigo snakes in peninsular Florida are also not as closely tied to gopher tortoise burrows during the winter as they are in southern Georgia, where indigo snakes depend on tortoise burrows for overwintering sites. This weaker association can make targeted searches around tortoise burrows, a proven technique in south Georgia, less reliable in Florida. So I was excited when fellow Orianne Society biologist Dirk Stevenson and his field crew decided to join me and my field tech, Zach Forsburg, to search for indigo snakes in Highlands County for a week in late January. We could sure use the extra help and Dirk is one of the best at finding indigo snakes (and everything else). And I was not disappointed with our results.

Using a combination of road cruising and burrow searches we captured four indigo snakes that week, plus a fifth snake that Zach had caught the week before. Two of those snakes came from an old field, formerly a citrus grove, whose grassy, sandy soil was pocketed with tortoise burrows, providing an abundance of shelter sites. Sure enough, in true south Georgia fashion, Dirk produced two indigo snakes and two more shed skins from the field. Five indigo snakes in one week shattered all previous records for indigo snake captures on this project!

At the close of the week, we had captured 26 indigo snakes in Highlands County since December 2010 as part of an Orianne Society study to determine how indigo
snakes respond to habitat fragmentation. Thirteen of these 26 snakes have received surgically implanted radio transmitters and we have been following these snakes throughout the past thirteen months. Most of these snakes have come from the Archbold Biological Station, where we have been focusing most of our search effort during 2011.

Being familiar with indigo snake radio telemetry in Georgia (having done some myself) I was very interested to see how these indigo snakes on the southern end of the Lake Wales Ridge behaved. Indigo snakes in Georgia remain on dry, open sandhills with an abundance of tortoise burrows during the winter, in order to use the burrows as overwintering sites.

Once things warm up in the spring, the indigo snakes begin moving off of the sandhills and start using a mix of upland habitats, flatwoods, wetlands, and floodplain forests for foraging and thermoregulation. Some male indigo snakes in Georgia may move two or miles from their winter sandhills to summer foraging grounds. Our Highlands County indigo snakes displayed a very different behavior. Our Florida indigo snakes did not display strong seasonal differences in movement or habitat use but rather moved back and forth across the same area (home range) throughout the year. When we estimated the home range size of our Florida indigo snakes, we found they were still sizable (over 200 acres) but much smaller than in Georgia (over 900 acres).

With one successful year behind us, we are excited about continuing our Highlands County indigo snake research and better understanding how habitat fragmentation affects these amazing snakes. This new year will see a few shifts in the focus of our research. We are now focusing our search efforts in suburban habitats around the Archbold Biological Station which are highly fragmented by roads but still support indigo snakes. Studying these “suburban snakes” will give us a better picture of how individual indigo snakes respond to habitat fragmentation.

We are also beginning to develop population models, using the data on individual indigo snakes that we are currently collecting, to determine how indigo snakes respond to habitat fragmentation at a population level. Understanding how populations respond to habitat fragmentation allows us to evaluate the ability of indigo snakes to persist in particular landscape long into the future.

As more of Florida’s natural habitats become lost or fragmented it is important to determine where indigo snake populations are most at risk so that their threats can be mitigated. But we also plan to use these models to determine where viable populations of indigo snakes can still persist. Knowing if human disturbed or modified habitats can continue to support viable populations of indigo snakes could provide a big boost to the conservation of this species in Florida.