Monday, August 26, 2013

Indigo Success

By Jim Godwin

    It’s the end of another season of monitoring of the Eastern Indigo Snake reintroduction project in Conecuh National Forest. During the winter months biologists and experienced volunteers have been systematically scouring the sandhills and longleaf forest for indigo snakes, using Gopher Tortoise burrows as cues in their searches. With the close of this round of monitoring we have documented a score of males attending females, multiple gravid females, and a few juveniles. Supplemental snake releases have been curtailed as the number of sightings of snakes has increased in the past few years and solid documentation of reproduction, population growth and expansion is now a fact. The Eastern Indigo Snake reintroduction into Conecuh National Forest is a biological success.

    Okay, so the preceding paragraph is a complete fabrication, but this is the level we wish to reach before we are confident that our efforts with the indigo snake have been successful. 

    In a previous blog post a question from a reader was put forth, how do we measure success of this indigo snake reintroduction? The question is simple, the answer is not. Our ultimate goal is to establish a self-sustaining population of the Eastern Indigo Snake in Conecuh National Forest, that is, a population that can maintain itself without human intervention. So, how do we know when we have reached that goal? And are there other measures of success to this project? 

    The simple indication that we are on the road to having a self-sustaining and reproducing population will be with the first capture of a snake lacking a PIT tag; each snake that we have hatched in the lab has received a PIT tag. PIT is an acronym for Passive Integrated Transponder. Every PIT tag, about the size of a grain of rice, carries a unique code, such as 3D9.1C2D31F90F. PIT tags never wear out, thus will last throughout the life of a snake. But to know the code carried on a PIT tag a PIT tag reader must be used. The reader sends a signal that is reflected from the PIT tag which is then shown on the screen of the reader, thus allowing a researcher to know the identity of the snake. 

    But merely finding one snake lacking a tag is not sufficient evidence that we now have a viable population, but it is a good first step. The real answer to the question may not come for decades. The key to this is, of course, reproduction, and this begs the question - can the snakes reproduce in the wild?  Keep in mind these snakes, until being released, have spent the entirety of their lives in isolation in a small plastic tub. And this leads to another question – has captivity altered their instinct to reproduce? I’ll answer the questions with a few examples. 

    Radio-telemetry has been vital tool in researching the fate of the released snakes. With the first three releases most of the snakes contained a radio transmitter, and due to the small size of the snakes the transmitters had to be small. The transmitters run on a battery and the small transmitters initially used had a battery life of less than a year. Snakes were released in the spring and had to be recaptured after the first winter of living in the wild because we wanted to replace the small transmitter with one with a longer battery life. 

    In the spring of 2011 we brought the 2 ½ year old snakes back into the lab for transmitter replacement. One female (A6) had a “dead” transmitter, yet when we scanned for her PIT tag we realized that this was a snake we thought had  died the previous summer. Huh!?!? Back in the summer the transmitter belonging to A6 was found lying on the ground therefore we assumed she had died. Yet some months later her PIT tag tells a different story and we began to suspect that she had lost the transmitter. To confirm this we had her x-rayed and, yes she was missing her transmitter, but surprise! she was also gravid (carrying eggs). 

    Now, this finding of a female snake with eggs was a year earlier than expected, and while none of the eggs were viable this was an indication that the snakes were capable of at least attempting reproduction. One year later, the spring of 2012, was the time when we discovered that females were becoming mature at 2 ½ years of age and that mature males were roaming the woods. At this time we captured two females, one 2 ½ years old and the other 3 ½ and both laid clutches that produced young. From this we know that these snakes can perform this most basic aspect of their biology.

    We have had to trust that these lab-raised, perhaps ecologically naïve, snakes would possess the innate behaviors needed to integrate into the natural framework of finding shelter, avoiding predators, foraging and capturing prey, surviving the winter, reaching maturity, finding mates, reproducing, and so forth. Thus far the indications are that the snakes are hitting the ground with the needed intrinsic behaviors.

    We can also view this reintroduction to be successful on a partnership level. Academic institution, state and federal agencies, and non-profit conservation and educational organizations have come together for the benefit of the eastern indigo snake. Auburn University has been at the center with research and implementation but the project would not have been possible without support and contributions from the Alabama Department of Conservation and Natural Resources, The Orianne Society, Georgia Department of Natural Resources, U.S. Fish and Wildlife, U.S. Forest Service, Zoo Atlanta, and Ft. Stewart (U.S. Army). 

    Eastern Indigo Snakes freely roaming the forest have opened up an avenue of educational opportunities. Snakes, nor any other organism, recognize artificial human boundaries, and our indigo snakes have on many occasions made this very evident. Not too distant from the release area is the Blue Lake Camp, a rustic camp of the United Methodist Church. Within a few weeks at least one snake found their way to the camp. As readers of this blog know, the appearance of a snake on a property is often met with a hoe, shovel, or firearm, but not in this instance. Having a radio transmitter allowed Jimmy and Sierra, our Conecuh ambassadors of snake education, to locate the snake(s) on the property, speak with managers of the camp, and illuminate the importance of the snakes. The fact that they eat Copperheads was not downplayed. 

    Ultimately the Eastern Indigo Snakes must be accepted by the human visitors of Conecuh National Forest. Being a national forest dictates a multi-use approach, and the visitors to the forest span all of society. Signs have been posted within the forest to alert and educate visitors of the presence of the indigo snake. Some will see the presence of the indigo snake as a once-in-a-lifetime opportunity to experience first-hand an iconic ruler of the longleaf pine ecosystem, others, unfortunately, not so much. But when we set forth with this reintroduction effort we made the decision that snake persecution would be a real possibility and that information and education were the best tools to combat it. 

    The overall success of the Eastern Indigo Snake reintroduction into Alabama depends upon a patchwork of success of seemingly unconnected areas spanning ecological, bureaucratic, and societal realms.

You can view previous blog posts about indigo snakes here and you may be interested in the following scientific article:

J. W. Gibbons, & K. M. Andrews (2004). PIT tagging: simple technology at its best BioScience, 54 (5), 447-454 DOI: 10.1641/0006-3568(2004)054[0447:PTSTAI]2.0.CO;2

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