With its many swamps, ponds, rivers, Westborough offers us the exciting possibility of meeting a native snapping turtle.

Why exciting? After all, turtles are slow and lumbering on land.

For that very reason, some excitement is likely if you or your pets encounter a common snapping turtle (Chelydra serpentina) on land. The snapper is likely to feel cornered, simply because it’s on land.

It will probably turn to face you, and it may hiss, lunge, and snap its jaws, threatening to bite. It puts on a show of being ready to defend itself. The thing to do, of course, is to realize that you’ve cornered a wild animal and back off.

Snappers have a fearsome reputation, in contrast to our peaceable image of most other turtles. Turtles are famous for protecting themselves by withdrawing – quite literally. For example, our eastern painted turtles (Chrysemys picta) defend their head and legs by pulling them inside their shell, where they’re safe. (Painted turtles are the ones we usually see sunning themselves on logs in ponds.)

Snapping turtles, on the other hand, can’t pull their head and limbs all the way in. Their small-sized lower shell isn’t big enough. They have no choice but to defend themselves on land by biting, just as many other animals do.

In water, snappers are not fearsome. In their element, they are swift and maneuverable. They simply swim away if you unsuspectingly approach or even step on them. Like most other wild animals, they prefer to retreat to avoid trouble. Contrary to what some people think, they don’t hunt the fingers and toes of swimmers.

The other reason for excitement when you find a snapper (or any turtle) on land – especially on a roadway – is concern for its safety in traffic. That dark rock in the road may be a turtle! A big rock could be a snapper. Most drivers have the good sense to avoid running over something that looks like a rock, since rocks aren’t good for vehicles, but unfortunately some turtles become road kill.

Sometimes, drivers may see a “Turtle Crossing” sign, such as on Arch Street near Mill Pond. But these signs are few and far between, and humans have created other dangerous barriers to turtle crossings, such as the local railroad tracks that posed a hazard for the young snapper in this week’s photo.

What are snappers (and other turtles) doing on land anyway? Why does a turtle that lives in water cross a road or trail? One big reason is to get from one wet area to another. For example, snapping turtles may visit woodland vernal pools in the spring to hunt frogs and salamanders that collect there to breed. Human development has created roads and railroads that slice up wetlands and open space into smaller sections, so many animals end up crossing roads in their normal travels. (We see “Deer Crossing” signs more often than “Turtle Crossing” signs.)

Another big reason for snappers (and other turtles) to move over land is to find a suitable nesting area for their eggs. Typically in June, females haul themselves out of the water to search for a sandy place to lay their eggs.

We don’t think of Westborough as sandy, but the retreating glaciers left scattered sand and gravel deposits here and all over the eastern third of Massachusetts, some 14,000 years ago. Human sand and gravel operations benefit from them, and turtles find them and dig nest holes with their back legs.

Some holes are false nests, but the female turtle finally chooses one, deposits her eggs, and covers them. Snapper eggs are about the size of ping-pong balls. The female leaves them to be incubated by the warmth of the sun on the sand.

The sun’s warmth also determines the sex of the turtles developing inside the eggs. During a certain early stage, eggs at low and high temperatures (55 degrees F and 77 degrees F) produce females. Eggs in the middle range (say, 73 degrees F) become males. Temperature varies within a nest because some eggs lie deeper than others, so one nest may produce both males and females. What will this year’s cool, wet summer produce?

Turtle eggs may be hidden under the sand, but they’re far from safe. If you walk near a sandy area along a shore or bank, look for what’s left on the ground after a predator raid: slightly rolled, leathery shards of turtle eggs. Some turtle nesting areas can be so covered with the remains of eggs that it seems surprising that any survive.

Skunks are the usual raiders, but raccoons, foxes, and coyotes also dig up and eat turtle eggs, usually soon after they’re laid. The false nests that turtles dig may serve to confuse predators.

August and September are the months for baby turtles. Snappers are the size of a quarter when they hatch, dig themselves out of the sand, and head for water. On land and in the shallows, many of them make a meal for snakes, birds, big fish, and even other turtles.

Adult snapping turtles are large and well protected from predators by their shell, but it’s legal to hunt them in Massachusetts. Snappers were the traditional meat in turtle soup, a favorite among New England settlers and Native Americans.

How do snappers get through the winter? The fact that they are cold-blooded may be key to their winter survival. Sometime in November, when our ponds begin to ice over, snappers bury themselves in mud at the bottom of a pond. They move little or not at all, and their metabolism – the chemical reactions in their bodies – slows way down. Remarkably, they don’t even breathe, but their skin may absorb some oxygen from the cold water. In April’s warmth, they become active again.

Snapping turtles are survivors. So are turtles in general, dating back 200 million years in the history of life, to the age of the dinosaurs. Turtles survived the mass extinction that killed off the dinosaurs (and 60 percent of the species on Earth) 65 million years ago.

Let’s respect and appreciate our local snappers!