Why Do Turtles Cross Roads? Nesting Season Explained

Nesting season: the main reason

Most turtle road crossings in North America and Europe happen during the nesting season. Female freshwater turtles lay their eggs on land, in soil that is loose, well drained and warmed by the sun. In the northern United States and southern Canada, the peak runs from late May to early July.

The common snapping turtle is the classic example. Females can travel a long way from the water to nest, and they are drawn to open, sunny ground: gravel road shoulders, railway banks, sand pits, lawns and gardens. A road built between a marsh and a sandy hill may lie directly on their traditional route.

Many females return to the same nesting area year after year. That loyalty helps them find good sites in a natural landscape, but it also means turtles keep crossing a road even after it has become busy.

Other reasons turtles cross roads

Nesting females are the most common turtles on roads, but they are not the only ones:

• Males searching for mates. In spring, male turtles may wander widely to find females.
• Hatchlings. In late summer and fall, baby turtles dig out of nests and head for water, sometimes crossing the same road their mother crossed.
• Moving between wetlands. Aquatic turtles leave ponds that dry up or become crowded and walk to new water, often after rain.
• Land turtles going about their lives. The eastern box turtle lives on land and wanders through woods and fields within a small home range. If a road crosses that range, the turtle will cross it, especially on warm, humid days and after summer rain.

Turtles cannot learn that roads are dangerous. Their defense is to stop and pull into the shell, which works against a fox but not against a car.

Why road deaths matter so much for turtles

Turtles have an unusual life history. Most eggs and hatchlings are eaten by predators, so populations depend on adults that live a long time and breed many times. A snapping turtle may take 12 to 20 years to mature, and an eastern box turtle often takes 7 to 10 years or more.

Because of this, even a small extra loss of adults each year can tip a population into decline. Modeling studies of freshwater turtles suggest that the loss of just a few percent of adults per year, which busy roads can easily cause, is not sustainable over the long term. In one population of common snapping turtles near a busy road in southwestern Ontario, numbers fell from 941 in 1985 to 177 in 2002.

Roads also hit females harder than males, because females make the long nesting trips. Surveys of turtle populations near roads have found more males than females, a sign that nesting females are being lost.

Which turtles are most at risk?

Land turtles and species that make long overland trips are the most affected. In the United States and Canada, these include snapping turtles, painted turtles, Blanding’s turtles, wood turtles and box turtles. The eastern box turtle is listed as Vulnerable on the IUCN Red List, and road deaths are among the main threats, together with habitat loss and collection.

In Europe, the native European pond turtle faces a similar problem in parts of its range, where roads separate the wetlands it lives in from the sunny slopes where females nest.

Crossing signs, fences and tunnels

Many communities now protect turtle crossings. The main tools are:

• Turtle crossing signs that warn drivers in nesting season, sometimes with seasonal speed limits.
• Exclusion fencing along the roadside that keeps turtles off the pavement.
• Tunnels and culverts under the road, linked to the fencing, so turtles can still reach the other side.
• Artificial nesting areas of sand or gravel on the safe side of the road, so females do not need to cross.
• Citizen science projects in which volunteers record turtles on roads to find the worst crossing points.

Studies show that fences combined with crossing structures reduce road deaths much more than signs alone. Fences must be built carefully, because turtles are good at climbing over or around gaps at the ends.

What drivers can do

The best help is simple: slow down near wetlands and ponds in late spring and early summer, and watch for what look like rocks on the road. If you see a turtle, do not swerve sharply or stop in traffic.

If you can safely help, wildlife agencies advise moving the turtle across in the direction it was heading, because it will simply turn around otherwise. Never take a wild turtle home or release it at another pond, since box turtles and many others survive best in their own home range. Snapping turtles can bite hard, so it is often safest to give them space and let them cross; see how strong is a snapping turtle bite?. Your local wildlife agency or turtle conservation group can explain the rules where you live.