CHESTERTOWN, MD — Research findings by Washington College biology professor Aaron R. Krochmal and a colleague published as the featured cover article in the February 2, 2015 issue of Current Biology reveal the startling degree to which the early learning experiences of turtles dictate their ability to navigate new territory throughout life.    

In the paper, “The Role of Age-Specific Learning and Experience for Turtles Navigating a Changing Landscape,” Krochmal and Franklin & Marshall College professor Timothy C. Roth relate the findings of a five-year study that involved radio tracking eastern painted turtles when the destruction of their native habitat forced them to find alternate sources of water. The study group was a population of turtles living in two ponds at DuPont’s Chesapeake Farms, a research farm near Chestertown.  When the ponds were drained each year for wetland improvement and waterfowl management, the turtles set out to find new ponds, which provided Krochmal and his student research assistants the perfect opportunity to study turtles on the move.

By radio tagging and tracking groups of turtles, then mapping their routes, the biologists monitored the routes taken by adult and juvenile turtles from this “resident” population and also of newcomer or “translocated” populations brought in from a pond some 11 miles away. As the Current Biology summary states, “Roth and Krochmal show that turtles respond to habitat loss by navigating to permanent habitat using highly precise paths. These paths are learned as juveniles during a critical period lasting three years. This is the first evidence that learning during a critical period may be important for how animals respond to changing environments.”One of the radio-tagged turtles Krochmal and his students tracked for the navigation study.

Krochmal says the journal article has already sparked significant interest in the scientific media, and not just because baby turtles are so darn cute. Among the most startling finding was the inability of adult turtles (beyond age 3) to learn a path to a new habitat the way their juvenile counterparts did. While the older resident turtles could still follow specific paths to an alternate habitat, none of the translocated adults could find water. Instead, they wandered aimlessly, dangerously losing body weight until being rescued by the researchers. At the same time, all of juveniles under the age of 3 succeeded in finding a new pond home, usually within 24 hours.   

“The adults could navigate just fine only if they had experience as juveniles,” Krochmal sums up. “They could not learn new paths.” 

The findings will be especially important to wildlife managers and conservationists. “This has ramifications for how we relocate turtles and other vertebrates to new habitats when natural habitats are destroyed,” the researchers conclude. “And it has implications for our understanding of how animals learn about their environment, the breadth of critical learning periods in vertebrates, and the factors necessary for the evolution of cognitive processes.”

Professor Krochmal is not yet done with turtles. He is now studying how that early learning period impacts brain chemistry — what physical changes come about because of early learning and experiences, and how they will come into play later in a changing environment. Asked about implication for humans, he says there may well be broader lessons about why the young mind is so much more capable of certain kinds of learning.  

Krochmal and his students talk about their work tracking the turtles in a 2011 video found here: http://www.washcoll.edu/live/news/705-landscape-ecology. 

Find the online version of the Current Biology article at http://ow.ly/IpIC6