Brumation

This turtle likely spends the winter tucked into the mud at the bottom of a pond or lake.

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When the weather turns cold, mammals may grow an extra layer of fur. In a heartbeat, birds can abandon harsh landscapes and move to warmer locations. Humans may add a coat or crank up the thermostat. What about cold-blooded, or more properly termed, ectothermic, species such as reptiles?

Reptiles, including turtles, tortoises, snakes and lizards, don’t have hair, can’t migrate long distances, and will quickly freeze solid if left in sub-freezing weather simply because their body temperature is determined by the environment. They can’t shiver to warm up, hug each other for warmth or pull on a blanket. All they can do is head underground, hunker down and wait for warmer weather, much like a bear in its den.

In mammals this is called hibernation, a state of almost suspended animation where heart rate and respirations drop, sometimes to only a few a minute, and body temperature plummets to just a few degrees above freezing. It takes time to arouse from hibernation, during which time the animal is totally vulnerable. In this sense, bears are not hibernators and neither are reptiles. Theirs is more of a torpor, something between a long winter’s nap and hibernation.

For reptiles, herpetologists call this state brumation. As might be expected, brumation is largely triggered by environmental conditions. Falling temperatures and shortening days signal that it is time to brumate. Appetite and activity decline and the reptiles seek shelter.

For lizards, tortoises and snakes, this shelter takes the form of a hibernaculum, which is Latin for, “tent for winter quarters”. A hibernaculum is usually underground beneath the frost line and deep enough that the temperature can stay reasonably uniform.

Many species are solitary brumators, but snakes are often the exception. It is common to find dozens to thousands of snakes in a single hibernaculum and you may find several different species as well.

You may recall the tale of the home in the Upper Valley that was built on top of a garter snake hibernaculum. Garter snakes by the hundreds invaded the house when it came time to brumate, finally forcing the human occupants out.

Turtles often choose different hibernacula. It is common for turtles to burrow into the mud at the bottom of lakes and streams and wait out the winter there. During this period of inactivity and immersed in cold water, respiration needs are minimal and are met by oxygen absorption from the water by the turtle’s throat and cloaca.

Since the external world plays such an important role in signaling brumation, I was a little surprised to go into the Valley of Fire visitor center near Las Vegas, Nevada, in December and find a sign stating that the desert tortoise was “asleep for the winter”. In this indoor environment where light and darkness are artificially controlled and the temperature is always predictable, why would this tortoise brumate? It turns out that beside exogenous (external) triggers, there are also endogenous (internal) triggers that may initiate brumation regardless of the environment.  The mechanisms are still poorly understood but the process has been well documented anecdotally.

It is humbling to realize that what we consider simple creatures have found some pretty amazing solutions to complex problems such as death-dealing cold weather. Just think what they might have done with opposing thumbs!

 

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Donate part of your tax return to support wildlife in Idaho!

On the second page of the Idaho Individual Tax form 40 you have the opportunity to donate to the “Nongame Wildlife Conservation Fund”.

Check-off this box on your next return or ask your tax preparer to mark the Nongame check-off on your behalf. You can donate any amount you wish, it all helps to support the wildlife you love.

If you are not from Idaho, check with your own state wildlife agency about how you can help. Many states have a similar program.

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Help Idaho Wildlife

When we traveled across the state in October 2017, most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.