By Wendy St. John, Nicole Christie, and Nick Geist:
Today was the big day for a cohort of juvenile turtles, as they swam in the waters of their home lake for the very first time. These western pond turtles (Emys marmorata) were hatched in the lab of Dr. Nick Geist at Sonoma State University (SSU), and head-started at the Oakland Zoo for nearly a year. Now that they’re big enough to survive in the wild, safe from predators, SSU students and Oakland Zoo staff released the juvenile turtles into Boggs Lake, in Lake County, California.
Head-starting Turtles
The concept of head-starting is simple: rearing young animals until they are old enough to have a better chance to survive in the sometimes harsh conditions of wild habitats. In practice, though, it can be complicated, but over the past few years, this collaboration between SSU and the Oakland Zoo has produced promising results. The turtles are kept under lamps to simulate sunlight, and fed a variety of foods they might encounter in the wild.
After about 10 months of growth, all juveniles were fitted with passive integrated transponder (PIT) tags – the same technology used to located lost pet dogs and cats. We hope that, after the turtles have been released, if they are encountered again at the field site, we’ll be able to identify them.
In 2010, 42 juvenile turtles were reared in the zoo and released into Boggs Lake. This year, we released nearly 80 of the juvenile reptiles.
The Big Day
On release day, Oakland zoo staff brought the juvenile turtles up to the field site, where they were met by students from Sonoma State University. Before being released, data was collected from each turtle this one last time: weight, and morphometric measurements including carapace length and shell height.
Welcome Home
Down at the lake, we waded out into open water, so we could release the turtles at intervals. Ideally, this would reduce the amount of competition for food and other resources between the new residents of the lake. Each of us had the opportunity to release at least a few of the turtles into the lake, and watch them take their first, tentative strokes.
I had mixed emotions about the turtle release. On the one hand, it is incredibly satisfying to know that we’ve given this cohort of turtles the best possible chance to survive and thrive at this beautiful site. It was somewhat bittersweet, though, as well – it’s difficult not to get at least a little bit attached to animals you’ve helped raise for nearly a year. In the end, though, satisfaction won out, along with a bit of pride for having been a part of something like this. And, of course, a wish for these young turtles to grow up strong and healthy in their new home.
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