How Male and Female Wood Turtles Use the Landscape Differently



Atop a mountain ridge, I heard a faint beep from my receiver – just enough to determine which direction I needed to hike to reach the turtle. An hour later, I found him, about a mile away from his last known location, and on the banks of a different stream. I began my search several hours earlier. “Legs”, a male Wood Turtle, had been missing for a couple of weeks. I suspected he was deep within his upland habitat and too far from a nearby road for me to detect the signal from his radio transmitter. So, I set off for higher ground, reminiscing about one of my first lessons in radio telemetry over 12 years ago. When in doubt, get high (in elevation). 

The missing male Wood Turtle as found near a stream.

Thanks to GPS data recorded by a logger, I learned that he walked about two miles to reach that spot. This year, he’s covered a lot of ground, as have a couple other males in the area. This is quite different from my past experiences tracking only females. Male and female Wood Turtles often use the same landscapes very differently. Like many wildlife species, females primarily search for the food needed to produce young, while males focus on finding females. You might expect their landscape use to be similar, but it’s not.

Female Wood Turtles spend more time away from water than males as they search for snails, leafy greens, fruit, and other food. They often travel up to around 1000 feet from streams, exploring forests, meadows, wetlands, and various other habitats in the area. When it’s time to lay eggs, they typically seek out sunny sandy spots near a stream and within their regular stomping grounds. If there aren’t any good spots near the stream, they might choose to lay their eggs in residential areas or along roads. In some cases, they might travel over a mile up or downstream in search of better nesting opportunities.

Female Wood Turtles spend more of their time foraging away from rivers than males, where they feed on snails, leafy greens, fruits, and many other things.

In contrast, males stay closer to the river and move back and forth along stream corridors. They might cover about a mile of stream each year, double the distance of most females. It’s important to note that there’s a lot of variation among individuals, with some making much lengthier trips, either in search of mates or to disperse to new habitat. Journeys in excess of a mile are almost always undertaken by males, and movements of over five or even 10 miles are not unheard of. The male I set off in search for this day has covered about three miles so far this year, and another nearby has traveled about two miles. Both will most likely return to where they started by fall.

So, if the males are searching for mates during their long-distance travels, why don’t they use the landscape the same way as females? Simply put, finding a female in upland habitat is like looking for a needle in a haystack. However, since females periodically return to the river, that is where a male is most likely to encounter them. Also, by traveling greater distances along streams, a male’s home range overlaps with a greater number of females. 

This map shows the movements of a male and female Wood Turtle from the spring through summer. Although these two turtles represent extremes, they are good examples of how differently males and females use the landscape.

Long distance travel by Wood Turtles does put them at risk, however. When moving along streams, bridges, culverts, and dams can force the turtles to cross roads where they can be killed. In more developed areas, these barriers can fully separate populations of Wood Turtles from each other and result in the death of every turtle that attempts to pass through.

Long distance movements by any animal puts them at risk of death or injury when they cross roads or other hazards.

Roads are actually the main reason we are tracking turtles at this central Vermont site. A few bridges and culverts will soon be replaced with wildlife friendly designs. What we learn by tracking Wood Turtles there may result in more targeted efforts to keep turtles off a state highway and guide them towards safe places to cross. Initially, our focus was just on the bridges and culverts in question. However, as the study progresses, we are also gaining valuable insight into long distance movements, and how the highway impacts the turtles on a landscape scale. More importantly, we are learning what we can do to help minimize the threat that highway poses to the species to help ensure their future in the area.