Summer lake water in Wyoming is always cool to chilly.
My first instinct - hard to believe that reptiles can survive for more than a few minutes without going into hypothermia.
I checked Google for average rattlesnake body temp...
Ideal comfort - 86-89 F.
Average temp in the wild - 70-74 F.
And, no, I do not know how you take the body temp of a wild rattlesnake!
Very carefully..........................
And, no, I do not know how you take the body temp of a wild rattlesnake!
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Thermometer on a stick?