Tracking Turtles
Biologist John Rowe’s laboratory resembles a turtle zoo.
Children’s wading pools converted into baby turtle habitats are arranged in rows in his darkened lab. Large curtains surround each pool, with lights, some brighter than others, directly overhead. Students maintain the lab, take measurements and analyze data pertaining to the scientific question: Does the intensity of light affect turtles and their shell coloring and growth rates?
Other students accompany Rowe to off-campus sites at Beaver Island in northern Lake Michigan and Brewster Lake near Hastings in southwest Michigan to study the foraging activity and movements of turtles using radio transmitters.
“We’re looking at some fundamental aspects of turtle biology that haven’t been done before because these types of studies take so much time,” says Rowe. “Most faculty researchers don’t have the time to be out in the field all the time. I have an army of students who can be in the field throughout the summer. We look at the effects of weather and temperature on turtle movements and activity. It’s a life history study of the turtle.”
At Beaver Island, Rowe and his students use radio telemetry to monitor turtle activity. Students capture turtles in the wild, apply radio transmitters, record data, and map turtle movements using GPS technology.
“We look at different habitats, observe how turtles spend their time, and study home range,” he says. “Other animals, like lizards, are easier to study. I’ve got 1,000 marked turtles in the marsh system at Beaver Island, but you’d never know it. You may see five or six sunning on a rock, but most are unseen. They don’t move fast and are under water and vegetation.”
Rowe and his students also study the environmental factors that cause turtles to change shell and skin color. Painted turtles that live on light-colored sand and algae-covered bottoms of Lake Michigan bogs tend to be light in color. Painted turtles that live on dark-colored muck-bottoms of inland lakes, swamps and marshes tend to be dark in color.
“We believe that light-colored turtles on light backgrounds and dark-colored turtles on dark backgrounds may blend in better in their respective environments,” says Rowe. “Therefore, they may avoid predation. In the lab, we’ve looked at factors such as light intensity and bottom color that cause turtles to change color as they grow up.”
In his Alma lab, Rowe, puts some newborn painted and red-eared slide turtles in a plastic container with the bottom painted black, and others in a white colored plastic container,
“We take measurements every 30, 60 and 90 days,” he says. “We find that turtles in the light container tend to get lighter, while the turtles in the black containers tend to get dark. Can the environment induce certain color patterns? Our research indicates the answer is yes.”
Rowe says student collaboration is essential, not only to assist him in his research and data collection but also for advancing student learning.
“I couldn’t do this without the students, and they gain an understanding of biology that they can’t get in the classroom,” he says. “They learn how to test a hypothesis and think about relevant questions. It helps with organizational skills, the synthesis of ideas, and collecting, handling and analyzing data.”
