When a turtle moves its head, its eye moves to compensate, so that its eye remains in the same position – parallel to the horizon or pond surface — no matter what position the turtle’s head is in. This type of eye stabilization is called vestibulo-ocular reflex (VOR). Humans have a very similar reflex, but it’s easier to detect on a Painted Turtle (pictured) because of its dark eye line. A turtle’s eye structure is stabilized to the horizon, which makes sense, as turtles spend their life close to the ground and/or the pond surface, and this reflex enables it to align its vision horizontally in order to find food, a mate and predators.
In May, at the very same time that adult painted turtles are laying their eggs, some of last year’s young turtles are migrating from their nest site to ponds or rivers. Painted turtle eggs actually hatch in late summer, with the young turtles remaining inside the nest cavity for varying amounts of time. Here in New England, in the northern part of their range, they often overwinter in their nest and emerge the following spring.
A hole 4” – 5” deep surrounded by scattered empty, dried up eggshells is a telltale sign of turtle nest predation. A painted turtle (judging from the size, depth and location of the nest) dug a hole in the bank of a beaver pond last summer and proceeded to lay roughly a dozen or more eggs in it. After covering the eggs with soil, the turtle returned to her pond. The eggs hatched in August or September. Sometimes young turtles immediately climb up through the earth and emerge above ground, but occasionally, this far north, they overwinter in their underground nest and emerge in the spring. A raccoon, fox or skunk discovered this painted turtle nest early this spring (the digging was fresh) and one can only hope that by the time the nest was raided, the young had already exited and headed for the nearby pond. Research has found that a very small percentage of turtle nests avoid detection by a predator.