JWM study: Where Maine’s montane amphibians breed

In the mountains of Maine, where spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus) breed in temporary vernal pools, they depend most on ponds that stay wet for longer periods of time. The salamanders were more likely to be found in beaver habitat, a recent study found, and wood frogs tend to lay their eggs in big, shallow wetlands.

The findings from the research, the first of its kind in the Appalachians’ high-elevation wetlands, diverged from those of similar studies in other mountains. In the Rockies, for instance, factors of the broader landscape, such as the number of nearby streams, played a more important role in whether a breeding pool was occupied.

“It seems obvious,” said Luke Groff, a recent PhD graduate from the University of Maine’s Department of Wildlife, Fisheries and Conservation Biology, “but when putting together a management plan, it’s important to look at your system and then across systems and think, ‘Are the conservation dollars we put toward this species going to be well used if we base it on research conducted elsewhere?’”

Groff, a TWS member, is the lead author of the paper published this month in The Journal of Wildlife Management. His results suggest preserving beaver populations and big wetlands with large areas under three feet deep can benefit pool-breeding amphibians in montane Maine.

As part of a wider project on the life history of amphibians in Maine’s alpine pools, the biologists assessed how pool- and landscape-scale characteristics influenced the breeding chances of the spotted salamander and wood frog.

Starting in May 2013, Groff and his team repeatedly surveyed 135 wetlands and ponds for two summers. Vernal pools are ideal for amphibians because they don’t support fish and other predators. The researchers measured water depth and other habitat traits and searched for salamander and frog eggs and tadpoles in thigh-deep water using polarized glasses and, where the water was particularly turbid, dipnets.

They observed that pool-scale features such as beaver activity was correlated to the salamanders breeding. The likelihood of the frogs occupying a site increased with its area and the percent of shallows it contained.

“Large wetlands might have a larger catchment area, so they may receive more rain and snowmelt, stay wet longer and better support tadpoles,” Groff said. “Beavers build dams, and that will help retain water for longer as well.”

TWS members can log into the member portal to read this paper in the February issue of The Journal of Wildlife Management. Go to “Publications” and then The Journal of Wildlife Management.

Header Image: A researcher holds a spotted salamander egg mass from an alpine vernal pool in Maine. ©Luke Groff