A Declining Species



Amphibians are among the most imperiled animals on earth, with almost half of all species declining, and, according to a new UN report, about 40% are now at risk of extinction. Some estimates are that the current rate of amphibian extinctions range anywhere from 211 to over 45,000 times faster than what is considered “normal” in the 300 million years amphibians have existed. The reasons for these extinctions vary, with habitat destruction and the spread of chytrid fungus, as well as other pathogens being major factors. Here in the Great Northern Forests, we are very fortunate in that none of our reptile or amphibian species have gone completely extinct in recent centuries (so far as anybody knows). But there have been extirpations (localized extinctions), and plenty of species are losing numbers and territory. While most of Vermont’s 22 species of frog and salamander remain common, there is good reason to believe we have lost at least one species so far, and it was practically gone before we even knew it existed here.

Boreal Chorus Frogs, which are closely related to Spring Peepers, were never common in Vermont for as long as anybody has been keeping track. In fact, when our partners at the Vermont Reptile and Amphibian Atlas published the first species list for the state, the Boreal Chorus Frog was not included because the curators of the atlas could not find any documentation of the species here. It wasn’t until shortly afterwards that they learned from a biologist named Fred Schueler that they had missed a species. Fred had heard chorus frogs in 5 towns in Franklin and Grand Isle Counties while surveying the distribution of the species around Lake Champlain with his wife, Aleta Karstad, and brother in the 1970s. However, subsequent attempts to locate the Boreal Chorus Frog were only successful in one town, Alburgh, in 1999. Since then, nobody has seen a chorus frog in Vermont (that we know of) and the most recent record we have of the species was from Canadian biologists who reported hearing chorus frogs in a nearby town from across the Quebec border in 2007. I’ve been up there at least a dozen times to look in the past decade, but thus far, to no avail. 

Boreal Chorus Frogs are similar to Spring Peepers, but instead of having a light X on their back have light stripes instead, and sometimes are green instead of tan.​
Similar to the trill call occasionally made by Spring Peepers, the call of the Boreal Chorus Frog sounds more metallic and is often compared to that of a fingernail running down the bristles of a metal comb or a socket wrench being twisted.

Vermont isn’t alone in losing that particular species, whose range is quite extensive. Out west, the species can be found from southern New Mexico all the way up to northern British Columbia. On the East Coast, though, their range is quite limited and disjunct from their western counterparts, only occurring north of Lake Erie and extending east up the Saint Lawrence River towards Quebec City. While boreal Chorus Frogs are in decline throughout their range, they have practically vanished from parts of their eastern range.

Since Vermont was on the very edge of that range to begin with it should not come as a great shock if the species is never seen here again. The exact reasons for this decline are not fully understood, but overall the Boreal Chorus Frog appears to be highly prone to site-specific extirpations caused by random events and disturbances, such as droughts. In an ever increasingly fragmented landscape, nearby populations that are able to survive such disturbances cannot recolonize areas where the species was lost, so one by one the eastern populations are just blinking out.

The Boreal Chorus Frog range (in red) is very extensive, but the eastern portion of the range is not connected to the western portion and frogs there are in rapid decline. Map source: https://tinyurl.com/y2vqwtrm

As is true for many species, maintaining and restoring habitat connectivity is absolutely critical to their survival. Even in places such as the Great Northern Forests, the landscape is being developed at an ever increasing rate. In Vermont, for example, we lose an area equivalent to the size of the entire city of Burlington every ten years to development, and that development is spread out across the entire state. As that happens, not only is wildlife habitat shrinking, but patches of good habitat are getting farther away from each other making it more and more challenging for wildlife species such as Boreal Chorus Frogs to maintain viable populations or recolonize lost territory after a disturbance. 

While the Boreal Chorus Frog was the first amphibian in Vermont presumed extirpated, others are in decline. Mink Frogs, for example, are widespread in the northeast part of the state, but the edge of their range appears to be receding to the north and in many of the old Mink Frog border towns the species has not been documented in over 25 years. Even common species are at risk. Eastern Newts, which are ubiquitous across much of the landscape, are considered highly susceptible to population collapse if an amphibian pathogen commonly referred to as Bd (Batrachochytrium dendrobatidisarrives, and experts on the subject consider the arrival of Bd to be a matter of when, not if. 

While most people might not have noticed the disappearance of the chorus frog, losing something like the Eastern Newt (who’s bright orange juveniles known as “red efts” are an iconic character in the northern hardwood forests) would certainly turn some heads. The problems facing many amphibians are common among other wildlife species, and habitat fragmentation is a problem on a global scale. Targeted conservation and habitat restoration can do a lot to help maintain connectivity across the landscape, which is why we at the Orianne Society utilize a landscape-focused approach to conservation. In our Great Northern Forests Initiative, we have chosen the Wood Turtle as our flagship species, around which we focus our conservation efforts, but it’s not just about Wood Turtles. Protecting and restoring habitat connectivity within high priority Wood Turtle areas doesn’t just help one species, but all of the reptiles, amphibians, and countless non-herp species they share the landscape. Efforts such as these help ensure the species we still have stand much better chances of remaining a part of the ecosystem for a long time to come. 

Despite being widespread in Northeastern Vermont, the Mink Frog appears to be losing territory and has not been documented in many towns right at the edge of their range in over 25 years.