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Homeothermic/Poikilothermic (warm-blooded/cold-blooded)

The higher order animals include reptiles, fish, amphibians, birds and mammals. Mammals and birds are homeothermic (sometimes spelled homothermic) but in simpler terms, warm-blooded. These animals are able to maintain a stable body temperature regardless of the temperature of their surroundings. In most cases, their body temperatures are higher than their environment. Humans, warm-blooded of course, have a normal body temperature of 98.6 degrees F.

Mammals and birds, in order to meet the caloric demands to keep their bodies warm, eat rather large volumes of food daily. It takes a lot of “fuel” to maintain our body temperatures just as it would require much fuel to heat your homes in winter. Many calories are burned just to keep homeothermic animals warm.

Some mammal species are able to drop their body temperatures in order to hibernate. Woodchucks, and the bat species that hibernate, are able to drop and maintain their body temperatures at about 40 degrees F. Hummingbirds on cold nights, who already expend so much energy in their flight and daily activity, need to go into a state of torpor and can drop their body temperatures to conserve energy.

Poikilothermic animals (cold-blooded) have their body temperatures regulated by the temperature of their surroundings. In the Times News coverage region, frogs, toads, salamanders, turtles and snakes are all cold-blooded. They also hibernate during the cold winter months. Most toad and frog species bury into the muddy bottom of a pond or marsh, or into the soft bottom of a streambed. During that time they are capable of absorbing life-sustaining oxygen through their thin skin, and have a body temperature just above freezing.

It may surprise you though, that two frog species in our area, the wood frog and spring peeper, often freeze in the winter. They usually hibernate by digging into the forest leaf litter and soil. More than half of their body liquids will actually freeze during the coldest times. As the spring season warms, they basically thaw out, and as you might be aware, are generally the first amphibians to breed.

Snakes and turtles also hibernate. Rattlesnakes and garter snakes often return to the same denning areas each autumn, escaping the harshest winter temperatures. Once out of the dens in spring, these animals seek warm, sunlit areas to warm up their bodies. Rattlesnake hunters know to seek out “rattlers” on cool late spring days by finding them coiled up and warming themselves on a sunlit rock or rock ledge.

Folks who bike or walk along the Lehigh Canal or other local ponds have probably chased many painted turtles from stumps, fallen tree trunks, or even discarded tires where they too were seeking the warmth to help them efficiently prepare for mating and their summer feeding. This past week I observed both painted turtles and a wood turtle “soaking up” the sun on some of my birding outings. Hopefully, by the time you read this column, an old high school teammate and I will have found a few timber rattlesnakes to photograph on our Blue Mountain walk.

Test Your Outdoor Knowledge: True or False: Many hibernators actually raise their body temperatures every few weeks.

Last Week’s Trivia Answer: The goldfinch is usually our last local bird to nest.

Contact Barry Reed at breed71@gmail.com.

I found this 2-foot garter snake warming itself on some bridge rip rap rocks on a cool May morning. Remember, July's intense sun would heat their bodies too much so they then become more nocturnal. BARRY REED/SPECIAL TO THE TIMES NEWS
Surprisingly, wood frogs, the earliest out of hibernation in spring, can actually freeze during their hibernation time and survive.
On one of your nature walks, look for painted turtles “escaping” a pond's 50-degree water to warm in the sun on logs or exposed rocks.
Woodchucks eat heavily in late summer to store fat reserves for their winter hibernation. Even though they are warm-blooded, they can drop their body temperatures to conserve energy during the winter denning months.