New York CityBright green and viscous, Morningside Pond looks like a vat of unappealing pea soup. Styrofoam cups and plastic bags cling to the pond’s edge, bound in place by bubbles of green foam. This is, perhaps, what’s to be expected of an artificial pond in the center of a New York City park.

Still, there is life here. A stream flows over the exposed bedrock opposite the pond’s benches, and a few weeping willows bend toward the shore. And then there’s the row of nearly a hundred turtles lined up along the pond’s edge, glistening in the springtime sun.

These are red-eared sliders, the most popular turtle in the American pet trade. Native to Mississippi River and Gulf of Mexico, they’re bred