Take a walk along a trail near a shoreline in Westborough in early summer and you just might see a painted turtle, the most common turtle in North America.

Painted turtles (Chrysemyspicta) live in the water but like to bask in the sun, typically on a log sticking out of the water.  Mornings are a good time to spot them, as they warm up for a day of foraging for food after a night on the bottom of a pond. Often you'll see more than one, looking very much like bumps on a log from a distance. They also bask in the afternoon.

Turtles are cold-blooded, so basking helps them warm up their bodies. Sunlight also helps rid them of parasites such as leeches. If there's any sign of danger, basking turtles quickly dive back into the water.

You might also meet a painted turtle crossing a path in the woods near a pond, such as Lake Chauncy, Mill Pond, or Sandra Pond, or near a slow-moving stream or a marsh. If you happen to see one making its way across a road, be careful not to run it over!

Painted turtles are nesting at this time of year, from late May to mid-July.  Look for activity in the late afternoon or early evening. The females come out of the water and search for a sandy, sunny spot not too far from the water to dig a hole about four inches deep. There they lay their eggs and bury them, away from predators in the water. And that's the end of the parent's involvement. The sun will warm the buried eggs.

The baby painted turtles hatch about 10 weeks later, although the time can be shorter or longer. They have a special "egg tooth" that helps them break out of the shell. The hatchlings are about one inch long, about the size of a quarter. Once they dig their way out the nest, they crawl off toward the water. At this risky stage, many young turtles become a meal for other animals.

The gender of baby painted turtles--male or female--is not simply a matter of genetics, as it is with humans. Instead, the environment plays a role. The temperature at which the eggs incubate in the nest has a key influence. Lower temperatures (around 77degrees) produce males, and higher temperatures (around 87 degrees) produce females.  Not surprisingly, a temperature in-between, such as 84 degree, produces both males and females.

Painted turtles are named for the color on their lower shell.  Their upper shell is mostly drab olive or black,  providing camouflage in a pond. Underneath, painted turtles in our area are usually bright yellow.  The edges of the upper shell may also have red or yellow markings, and the turtle has yellow or red streaks on its neck, legs, and tail.

Painted turtles can live about 20 years, thanks partly to the protective armor of their shell. Their food includes vegetation, algae, leeches, snails, and insects, so they help to control organisms that we sometimes consider pests. Painted turtles don't hear well, but they have color vision and good senses of smell and touch. Especially when small, they can become prey for herons, raccoons, hawks, snakes, foxes, and larger turtles and fish.

These turtles tolerate cold temperatures but usually hibernate in the mud at the bottom of a pond in the winter. During hibernation, their bodily processes slow greatly. Painted turtles have lungs and normally breathe air, but during hibernation they absorb oxygen from the cold water through the tissue in their throat and special sacs near their tail.

Painted turtles are relatively small, usually about 4 to 9 inches long, and don't bite. It's best not to pick one up, since they have sharp claws that scratch. They can also harbor disease-causing bacteria.

If you spot a larger turtle, chances are that it's a snapping turtle (Chelydra serpentina). Snapping turtles grow 8 to 20 inches long and weigh 8 to 35 pounds. These turtles do bite and can be aggressive on land.