Sunday, December 7, 2014

Tracking Rattlesnakes: Predator/Prey Relationships & Conservation Issues

The Lehigh Gap Nature Center Speakers Bureau proudly presents Tracking Rattlesnakes: Predator/Prey Relationships & Conservation Issues.   According to the LGNC description:
Photo courtesy of The Morning Call
Howard Reinert, Ph.D., Professor of Biology at The College of New Jersey. Reinert and his advisor at Lehigh University, Dr. David Cundall, developed innovative tracking techniques to allow ecological studies of timber rattlers. These techniques are now used in tracking many species of snakes around the world.

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Today's presentation is Timber Rattlesnake Research: What's the BUZZ? Some background: Howard is a local person (Reading) who very early developed a knack for seeing things in the field. Learning quantitative statistics, Howard applied some of these techniques to habitat observations and tracking rattlesnakes and copperheads. He developed snake ecology by implanting transmitters in the species so they could be found at will. In the introduction to Howard and his presentation, Dr. Cundell said that no one alive knows more about rattlesnakes than Howard, whose goal is to preserve the ecology and habitats of the species to insure their longevity. Before beginning, Howard noted that he could speak indefinitely on the topic, so he intends to keep an eye to the clock.

Timber rattlesnakes appear predominantly in western PA in the mountainous regions. Some snakes are totally black but range to pale yellow to anywhere in between in variation. Local populations and how they evolve to their conditions determine the color. Sometimes very large snakes, about 72" but the largest in PA was seen by Howard at 54". Residing largely along the PA Appalachian Trail, timber rattlesnakes in PA are not an endangered species as they are in surrounding states. In PA, however, we maintain healthy populations as part of our native fauna.

How do you catch such a unique rattlesnake? Carefully. Their eyes are interesting as they bulge out. By the age of 4, Howard was a catcher of things along a creek, overturn rocks, and notice nature, with much credit going to his mother for inspiring him. By 7, Howard was catching his first snakes and this set him on the path to being a naturalist. In the early 1970s, people began putting transmitters in snakes so you could recapture them in their habitats and learn a lot, but only for a while because they "pass" the transmitters over time. And the whip antennas, while giving a greater range, still were not good internal tracking devices.

In his MS program at Lehigh University, Howard learned how a transmitter could be surgically implanted with whip antennas. Howard cites his LU professor Dr. Cundall for developing the idea. The benefit: an extended range for tracking snakes and learning from them. So what has he learned? Do timber rattlesnakes compete for resources with copperheads? Decades of sight observations suggested that these snakes populate the same habitat. Both pit vipers, copperheads and rattlesnakes would seem ideal competitors. After the study, Howard learned that rattlesnakes like wooded areas as habitats over rocky land masses, which were the copperhead's habitat.

Timber rattlesnakes really want to be in wooded mountainous areas whereas copperheads need open habitats for basking, incubating young inside, and skin shedding. Rattlesnakes eat in wooded areas and are impossible to find. You can hear it, but even within inches a rattlesnake will not move, rattle. They would just let you walk past them, that is until telemetry. In layman's language, a rattlesnake is an ideal predator and loves to catch prey while seemingly sleeping. They catch their prey by sensing heat--infrared rays from an animal--and the little animal is caught because snakes are great waiters. A snake can detect a small animal with its tongue better than a scent dog with his nose. Rattlesnakes select their logs and achieve success by waiting...

Is the forest tranquil? Not at all. Human interference--man and machines--do they have an impact on rattlesnakes?  Is logging harmful to rattlesnakes? Howard and colleagues set up a worse-case scenario and attempted to track and determine impact of high density rattlesnake populations by following 800 timber rattlesnakes. They tracked in 2003-2004 populations in tranquility. In 2005 they tracked and observed interactions between loggers and rattlesnakes to determine the logging response. In 2006, the after-logging impact was studied.

306 rattlesnakes were radiotracked with over 4000 field observations of rattlesnake behavior, the largest study of its kind of timber rattlesnakes. Mortality? From logging was amazingly low. Only 5% as compared to the normal 10% natural mortality. The good news: logging has relatively no impact on timber rattlesnake populations. Movement was not impacted either during logging. Snakes moved around but returned to original mating spots and do so for life. Often they travel 2 miles but the timber rattlesnake can travel over a mile a day during the breeding season.

Whether trucks, skidders, chain saws, loggers, nothing changed the patterns of life for timber rattlesnakes because it is THEIR home and they remain and return to it. No negative impact. And that's really good news for our understanding of the how man and snake can interact in the wild. Howard expected that the snakes would become frightened, leave. But they did not move. They held their ground. The snakes remained undisturbed by logging episodes, whatever they were.

In essence, the snake's response as a population: do what you want; it's my home and I'm not leaving. They did not vacate their habitat during logging, even during breeding and gestation cycles. Good news: timber rattlesnakes can tolerate disturbances, density increases and decreases, new foraging sites, new basking sites, different species composition and still ride out the changes, whatever they may be. So the bottom line is: rattlesnakes can adapt and survive, thrive, and rebound despite man's interference because they--the snakes--are an adaptable species.

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