Opportunities to see turtles in winter are extremely limited, but a hole chopped in pond ice recently revealed a Snapping Turtle swimming in the water beneath the ice. According to Jim Andrews, Director of the Vermont Reptile and Amphibian Atlas(http://vtherpatlas.org/ ), most turtles don’t often burrow into the mud during winter. They need to take in dissolved oxygen from the water and there is not much available in the mud. Turtles take in oxygen through the linings of their mouths and sometimes thin-skinned, capillary-rich areas in their cloaca and armpits. Many turtles are just sitting on the bottom of ponds. They may use a rock, log, or maybe some leaves for a little protection from otters or other predators.
If the ice is clear, it is possible to see turtles swimming beneath it. Andrews suggests that the Snapping Turtle in the photograph is likely picking up an oxygen boost by using its lungs for a change. It may be four more months before it gets another breath of fresh air. (Thanks to Jim Andrews for post and Barb and Paul Kivlin of Shoreham, VT for photo.)
Duckweed (Wolfia sp.), a free-floating aquatic plant that possesses flowers which are said to be the smallest flowers in the world, is coating our mystery creature. The presence of this plant can indicate that there are too many nutrients in the water, especially nitrate and phosphate. On the plus side, Duckweed provides waterfowl, juvenile fish and other wildlife (including humans in Southeast Asia) with a protein-rich (40%) food.
Under this green coating is a Snapping Turtle, one of the largest freshwater turtles in North America. Most often encountered in June, when females leave their ponds to lay eggs, Snapping Turtles are infrequently observed at other times of the year. This is primarily due to their crepuscular and nocturnal habits as well as their tendency to spend a lot of time under water feeding on plants, insects, fish, frogs, small turtles, young waterfowl, and crayfish.
Found in most ponds, marshes, streams and rivers, Snapping Turtles are not aggressive towards humans. Their size is impressive (a full-grown Snapping Turtle’s top shell, or carapace, can measure up to 20 inches in length) but they shy away from human disturbance. Miniature versions with one-inch long carapaces can be seen this month as the young Snappers crawl up out of their subterranean nests after hatching from eggs laid in June and head for the nearest water.
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If you’re of a certain age, you may remember having a small pet turtle (complete with a plastic container and palm tree) when you were young. Those turtles were Red-eared Sliders, and so many of them were released or escaped into the wild that they are now considered an invasive species and many countries ban their importation. Even though it is illegal for hatchlings with a top shell length of less than 4 inches (they can reach 16 inches) to be sold for anything other than educational purposes, many pet stores in the U.S. still sell them. Wild populations can be found in most of the New England states, though they are very localized in some.
Red-eared Sliders are named for the red ear stripe on both sides of their head, and the fact that when basking they typically slide into the water at the slightest hint of danger. They are semi-aquatic and strong swimmers; when not basking, they can usually be found in the water. Like many other species of turtles, the sex of Red-eared Sliders is determined by the incubation temperature during critical phases of the embryos’ development. Males are produced when the incubation temperature is between 72° and 81°F. and females develop at warmer temperatures. (Thanks to Sadie Brown for photo op.)
Being an aquatic species, most painted turtles hibernate in the mud at the bottom of ponds. They dig down as far as ten feet where they spend the winter hovering around 43°. In the spring, when the temperature of the water approaches 60°, painted turtles begin actively foraging, but the first priority upon awakening is to warm up their bodies. Turtles are ectothermic, or cold-blooded, thus the temperature of their bodies is determined by the environment that surrounds them. To be active, painted turtles must maintain an internal temperature of 63°- 73°. They reach and maintain this temperature by basking in the sun, particularly in the cold, first weeks of spring. Once warmed up, the turtles will forage, and when they begin to cool off, basking resumes.
Competition for basking sites such as floating logs and rocks can be fierce. It is not unusual to see many painted turtles lined up on a floating log, or turtles piled one upon the other on a rock in an effort to maximize the effect of the sun’s rays. The heat they’re obtaining increases their metabolism, aids in digestion and allows males to start producing sperm. The sun also strengthens their shells and reduces the amount of algae on them, thereby reducing the chances of bacterial or fungal infection.
After spending the winter hibernating in small streams and rivers, Wood Turtles awaken, become more active, mate (usually in shallow water), and eventually leave the water to begin foraging for food. Summer is spent mostly on land, traveling along streams — rarely do Wood Turtles stray farther than 1,000 feet from the water. In a few weeks, females will deposit between four and twelve eggs in a nest they dig in sandy soil.
Most aquatic frogs such as this Green Frog have been deep in hibernation for several months. A common misconception is that frogs spend the winter the way aquatic turtles do, dug into the mud at the bottom of a pond or stream. In fact, hibernating frogs would suffocate if they dug into the mud for an extended period of time. A hibernating turtle’s metabolism slows down so drastically that it can get by on the mud’s meager oxygen supply. Hibernating aquatic frogs, however, must be near oxygen-rich water and spend a good portion of the winter just lying on top of the mud or only partially buried. They may even slowly swim around from time to time.