One Cold Turtle!

By Jason Beale, Manager, Abbott’s Mill Nature Center

Most people have heard the term “cold-blooded”, but our perception of the word and how it applies to wildlife are often quite different.  The recent cold spell that kept furnaces working overtime brought out a surprise at Abbott’s Pond.  A Red-bellied Cooter (Pseudemys rubriventris) has been surface basking this winter.  During the initial sighting on January 4, day temperatures were barely above freezing and the nights were well into the teens.  Ice formed and briefly covered the pond.  Yet, the turtle remains a daily sighting amongst the backdrop of wintering Ring-necked Ducks and other waterfowl.

The Red-bellied Cooter's head is visible in the middle of the photo
The Red-bellied Cooter's head is visible in the middle of the photo. Photo by Jason Beale.

A warm-blooded or endothermic animal produces its own heat through internal processes while cold-blooded or ectothermic animals obtain the majority of their heat from an external source.  Yet, there I was, cold despite my layers of clothes observing an active reptile in a pond whose waters were just above freezing.  The turtle was indeed sluggish as it turned and dove, but it certainly challenged my notions of warm and cold blooded. 

JWPseudemys rubriventris Blairs Pond Milford DE 29 May 2005 047
Basking Red-bellied Cooter are a common sight at southern Delaware millponds from spring to fall. Photo by Jim White.

Red-bellied Cooters are generally active from March-November and are habitual baskers along with the Eastern Painted Turtle.  You may be familiar with these turtles and their large, rounded carapaces (top shell), as they sit on logs in warm weather.  The younger turtles have reddish markings, but become melanistic (darker) with age and older specimens may appear almost black. 

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Red-bellied Cooter in Abbott's Mill Nature Center Wet Lab. Photo by Jason Beale.

There are published reports of Eastern Snapping Turtles active under ice in the winter, but I found no mentions of winter Cooters.  Jim White, Delaware Nature Society’s Associate Director of Land and Biodiversity and co-author of Amphibians and Reptiles of Delmarva,  said, “Since they are completely herbivorous as adults, they don’t require much energy to feed.”  Therefore, they are able to meet their energy needs by surface basking and foraging for aquatic plants.  However, typical winter behavior for aquatic turtles is to hibernate by burying themselves into the soft mud at the bottom of ponds.  Despite having lungs and being air-breathers, they are able to exchange gases and oxygen through their skin, surviving for months.

References:
Ernst, C.H., J.E. Lovich, and R.W. Barbour. 1994. Turtles of the United States and Canada. Washington, D.C.: Smithsonian Institution Press
White, J.W., Jr. 2010. Associate Director Land and Biodiversity, Delaware Nature Society, Hockessin, DE. Personal communication.
White, J.F., Jr. and A.W. White. 2007. Amphibians and Reptiles of Delmarva. Centrevill, MD: Tidewater Publishers
  

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