Skip to content

“Cold-blooded”: Winter Survival of our Amphibians and Reptiles

Written by Logan Parker, Director of Programming and Assistant Lake Science Manager

Those of us who remain in New England throughout the winter know all too well the struggle to stay warm. For me, a typical January day begins with pulling on many layers of clothing, driving to Belgrade Lakes in the tropical microclimate of my heated vehicle, and dashing from the car into the comfort of the climate-controlled Maine Lakes Resource Center. All through the day, I eat a variety of foods that keep my metabolism fueled and my internal temperature controls operational. My evenings are often spent studying in an armchair beside the wood stove. Both modern technology and my own biology have made it so that I can endure winter in such a climate. Without either, I’m in real peril up here in a short amount of time.

There are some animals, however, which get by with much less. Enter the ectothermic reptiles and amphibians: the “cold-blooded” inhabitants of our watershed. Unlike endotherms, such as you and me, these ectotherms are largely dependent on environmental sources of heat to regulate their body temperatures. They have neither dense fur nor insulating feathers and lack the appendages to fly to more favorable conditions. No, our resident frogs, snakes, turtles, and salamanders must endure the Maine winter by deploying a different set of adaptations.

The Common Snapping Turtle (Chelydra serpentina)  is perhaps the least popular ectotherm in the watershed due to its aggressive behavior when encountered on land (although in water these turtles are quite meek and skittish). These large turtles have a long history of ambushing prey in the marsh, streams, and lakes of North America dating back some 60-100 million years (Coulter, 1999).  To survive the rigors of winter, these turtles retreat to below the water’s surface to spend the season hibernating under ice in shallow marsh areas, stream inlets, and under submerged trees (Ultsch, 2006). Snapping turtles will enter this mud-mired hibernation state alone or sometimes in the company of other turtles. These turtles, which typically breathe air, are anoxia-tolerant in winter- meaning they can survive several months underwater in even poorly oxygenated lakes (Ulsch, 2006). They are suspected of being capable of absorbing oxygen through folds of their pharynx that are exposed to water (Ultsch, 2006).

cliff-fairweather

A Common Snapping Turtle immobile beneath the winter ice. (Photo courtesy of Cliff Fairweather.

Unlike the snapping turtle, a number of native frog species survive the coldest months on dry land. Wood Frogs (Lithobates sylvaticus), Spring Peepers (Pseudacris crucifer), and Gray Treefrogs (Hyla versicolor) spend the winter near the soil surface under leaf litter, tree roots, and woody debris (Davis, 1999). This means these animals are exposed to a more dynamic array of freezing conditions. What is a native ectotherm to do? Why, freeze of course! Extreme conditions call for some equally extreme survival measures. To survive undergoing a freeze, these frogs reduce the water content of their organs and accumulate either glucose or glycerol (depending on the species) as a “cryoprotectant”, a substance that prevents cell damage during freezing (Layne et al. 2001). As much as 80% of the frog’s body will freeze during particularly cold spells.

Snakes lack the anoxia and freeze tolerance of the preceding species and so deploy a different set of adaptations to persevere through months of freezing conditions. The Common Garter Snake (Thamnophis sirtalis) is the most widespread reptile in the region and stays active sometimes well into November (Haskins, 1999). When the winds shift and snows begin to fall, these snakes head for crevices, rock walls, and old foundations to pass the winter singly or en masse, sometimes by the thousands (Shine et al. 2003). By retreating below the frost line, these snakes are able to avoid potentially lethal low temperatures at the soil’s surface (Shine et al. 2003). These animals remain in the hibernaculum until spring when they emerge, mate, and disperse.

mating_ball_of_garter_snakes

A “ball” of Common Garter Snakes mating outside their winter dens.

Through a variety of physiological and behavioral tactics, our watershed’s native ectotherms endure the harshest part of the year. As with all of the various life forms that inhabit our watershed, proper habitat must be fostered if they are to flourish here. Each of us can contribute to the success of these animals by preserving wild spaces and propagating habitat on our own land. Furthermore, the lakes, streams, and vernal pools in our watershed are of vital importance to wildlife. The needs of the biotic community must be maintained when considering the management of this resource.

References:

Coulter, M. W. (1999). Common Snapping Turtle. Maine Amphibians and Reptiles. University of Maine Press. Orono, Maine, USA.

Davis, S. L. (1999). Gray Treefrog. Maine Amphibians and Reptiles. University of Maine Press. Orono, Maine, USA.

Haskins, J. J. (1999). Common Garter Snake. Maine Amphibians and Reptiles. University of Maine Press. Orono, Maine, USA.

Layne, J. R. & Jones, A. L. (2001). Freeze Tolerance in the Gray Treefrog: Cryoprotectant Mobilization and Organ Dehydration. Journal of Experimental Zoology. 290: 1-5. 

Shine, R. & Mason, R. T. (2003). Patterns of mortality in a cold-climate population of garter snakes. Ecography. 12 (2): 81-86.

Ultsch, G. R. (2006). The ecology of overwintering among turtleswhere turtles overwinter and its consequences. Biological Reviews. 83 (3): 339-367. 

Role changes at the MLRC

Picture: Logan Parker (left) and Brenda Fekete (right).

The Maine Lakes Resource Center (MLRC), home of several local environmental groups, announces the appointment of Brenda Fekete as Interim Executive Director/Lake Science Manager.  Ms. Fekete has served as Lake Science Manager for the last two years, working with Colby College faculty and student interns on collecting data from all of the lakes in the Belgrade Lakes Watershed and analyzing the data at the Colby College facilities and in the Colby wet lab at the MLRC. She will continue as Lake Science Manager and Interim Executive Director with the help of Logan Parker, whose responsibilities have expanded to Director of Programming/Assistant Lake Science Manager.

The Maine Lakes Resource center is organizing and adjusting staffing to meet anticipated needs and challenges of the future.  The organization has retained a development consultant and plans to hire a permanent executive director.  Kathi Wall, former administrator of the MLRC, has elected to step down her level of involvement.  She developed parallel programming around the intersections of science and the arts at the MLRC Annex. The Annex, which was an extension of the MLRC located in a separate building adjacent to the Belgrade Lakes Post Office, will now be operated separately by Kathi Wall as a creative center.

For more information about the MLRC’s staff, click here!

 

Water Quality Update – November 2016

The beautiful and unseasonably warm fall has allowed us to sample two weeks longer than last year, but it is time to call it a season and bring in the boats! Although only the deeper sites in Long Pond and Messalonskee Lake have not experienced fall turnover, we have collected our final water profile, grab sample, and secchi reading from each of the ten sampling sites. We have also finished the sediment sampling on all of the seven lakes. A big thank you to the volunteers that braved the colder fall weather. We could not have finished our sampling effort without you! Due to the lack of ice, were unable to collect winter samples last year. We are crossing our fingers and hoping to get the snowmobiles out this year!

larchinserpThe off season will be very busy with water and sediment sample analysis (at Colby), data analysis, comparison of 2015-16 data, lake remediation meetings and logistics for winter and spring sampling. Stay tuned for another community update meeting in the spring!

Goldie was removed from Great Pond on November 7th. She will be cleaned up and on display in the MLRC gallery throughout the winter season. The Goldie website is a great place to find a summary of the data that she collected from May through early November.

Another place to find the water profile data collected from May through November is right here on MLRC website. I have recently posted the final data set for each of the seven lakes. I have displayed the data in a fall season profile to make the progression towards lake turnover easier to see. The Interactive map also displays the most recent data for each of the sampling sites.

The FlowCam will remain in the Colby Water Analysis Lab at the MLRC and will continue to be used for phytoplankton analysis by the research team. Feel free to stop in and look at the awesome pictures if you happen to be in the gallery while we are working!

It was great seeing new and familiar faces at the October Water Quality Community Meeting. The Colby Capstone students will be presenting their exciting lake data on December 6 at 1pm in the MLRC gallery. Hope to see you then!

_dsc6147Very bittersweet… the colder temperatures required lots of layered clothing, but the beautiful fall colors and lake wildlife that was enjoyed while sampling will be missed! It was a great 2016 season!

Wishing everyone a wonderful holiday season! Bring on the snow!

14884478_1094366320681240_1690109907146442563_o