Reptilian Research: Turtle Biologist Studies Habitat
(Posted November 18, 2013)
HUNTINGDON, Pa. -- Imagine a turtle hatchling emerging from the ground within the forest surrounding Lake Raystown, after burrowing from an underground nest where the eggs were laid. The hatchling will now instinctually make its way down to the lake. But something is blocking the path of the hatchling: a metal cage, surrounding the entire nest.
There's no need to be alarmed -- the cage was actually there for protection, and the turtles won't be trapped for long. Not long after the hatchlings emerge, Roy Nagle, director of environmental health and safety and instructor of environmental science at Juniata College, will arrive with his students and carry the tiny hatchlings safely down to the water. This turtle research project is just one of many conducted by Nagle.
"We work on physiological ecology and population ecology by catching turtles and marking them," says Nagle. "Our goal is to follow individuals through time and understand how they survive and reproduce so as to get an idea of how populations are changing."
Nagle is also interested in the specifics of maturation and reproduction for certain central Pennsylvania turtle species, such as the box turtle. The scenario described at the beginning of this article is part of the central Pennsylvania turtle study.
"For most turtle species, eggs are laid underground in June," explains Nagle. "Then they hatch in late summer, and then the hatchlings eventually come out of the ground and move to water. No one's really looked at box turtle nests systematically to know when they emerge. That's what we're doing now."
"For most turtle species, eggs are laid underground in June. Then they hatch in late summer, and then the hatchlings eventually come out of the ground and move to water. No one's really looked at box turtle nests systematically to know when they emerge. T
"I've done conservation-based research that's just about collecting raw data," says Alexandra Witter, a senior from Short Hills, N.J. and one of Nagle's research assistants. "Roy's work is more than that because he's really interested in finding something out."
Out at the Raystown Field Station, Nagle and his team put radio transmitters on box turtles (a process known as telemetry) so that they can follow where the turtles go. In this case, Nagle waited until five nests were laid last June before putting wire cages around them to keep raccoons from digging up and eating the eggs.
"Our job with these nests is to check them every few days," says Nagle. "When the hatchlings emerge, they'll be stuck in the cage until we get there and find them, which lets us know when they came out."
"We dug up some nests," says senior Gabrielle Cannon, of Hummelstown, Pa., another one of Nagle's research assistants. "There were some eggs that weren't going to make it on their own so we incubated those, and then had little baby box turtles that we got to put back into nature."
"We've worked with a lot of baby turtles," says Witter. "At least two whole nests full so far."
Nagle's team also uses telemetry and temperature probes to determine the nature of box turtle hibernation. They have also tracked and protected some snapping turtle nests, as well as another project involving the telemetry of wood turtles.
"Wood turtles are a species that has declined almost everywhere it exists, but the Raystown population seems to be fairly stable," explains Nagle. "So it's important to figure out why that is by looking at their home range, habitat, and hibernation."
Nagle also likes to incorporate his research into his teaching. For example, for one of his guest lectures for "Conservation Biology" at the Raystown Field Station, there were currently two turtle nests where 40 hatchlings had emerged. Since the class had 35 students, Nagle allowed the students to each release one hatchling into the lake.
"It was kind of fun," says Nagle. "There's something nice about that, the personal connection you can make. But I don't keep animals in captivity, which is one of the big messages I want to tell students here and people out there. If I give a talk sometimes I'll try to pick up an animal for the talk, and then tell the kids that I'm taking the animal right back to where I got it, which is what I want them to do."
Nagle is always looking for student assistants, like Cannon and Witter, for his ongoing turtle research.
"I did a sea turtle internship over the summer," says Witter. "And I wanted to do more research with turtles, so it was convenient that Professor Nagle is conducting this ongoing turtle research."
"The whole methodology is figured out for us," says Cannon. "So we can't really deviate from it too much, because they've been tracking these turtles for years and we don't want to change it now. We're continuing a research project that's already in motion."
Cannon says that her research experience has been great, especially since she's learned transferable field methods such as telemetry.
"I really enjoy it," says Cannon. "If I could do field based research forever, that'd be great."
By John Dubensky
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