From another thread. I thought I would move it here so as not to totally hijack the other thread.
The question posed was: Would a snake in the wild voluntarily use surface temps 100F+?
And if so, what are the environmental conditions that would warrant such use?
Chip said the following
Quote:
Yes. At least on *part* of their body they will. I've seen wild water snakes throw a coil over a supremely hot surface (150+) in the sun for a minute, move it a few inches, then dip back under water many times. I have caught many corn snakes on hot roads after a rain and quick temperature drop. Snakes can be collected under tin so hot that they don't even feel cool to the touch like our captives do.
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I disagree.
1. Was the wild water snake wet when it first touched the hot rock? Latent heat exchange would effectively reduce the sensible heat change to 0 for the animal. Like stepping out of a pool onto hot concrete, as long as your feet are wet, it doesn't burn. Once feet are dry, you can feel how hot it is, and so you step into the grass, jump back into the pool, or scream in agony. The snake chose option 2.
2. Snakes in the rain is the same deal with latent heat exchange. They're wet, the road is wet, and I bet they're just passing through too. El Jefe had some interesting points about road cruising and snake temperatures.
3. A snake
under hot tin is much different than one
on the hot tin. I suspect the temperature under the tin is radically different than the temperature on top of the tin. The shade provided by the tin can make a 10F temperature difference alone. Secondarily if there is any evapotranspiration gonig on, if the snake is in vegetation under the tin, or any soil moisture (again with latent heat exchange perhaps). Plus the tin might be reflective too, deflecting quite a bit of shortwave radiation away from any creature underneath.
I could be wrong on all of these counts as I am not a snake, but I bet there are many more processes to sensible heat regulation for a snake than we sometimes think about.
So yeah a snake may encounter 100F+ temps in the wild, just as it might encounter a hawk or a hiker, but is it going to use them? Do we have any evidence that it is using the 100F+ temperatures? I have yet to find any.
Oh yeah, and somebody
did do a study implanting temp probes into snakes. The article title is:
Body Temperature Variation in Free-Ranging Hognose Snakes (Heterodon platirhinos).
Quote:
We observed 49 cases during the activity season in
which H. platirhinos were tightly coiled, fully exposed
to solar radiation, and judged to be ‘‘basking.’’ In 40 of
the 49 cases, Tb ranged from 0.3–11.7C (mean =
4.8C) above Tair (mean = 23.1C; range 14–29C). In
nine cases, Tb ranged from 0.0 to 25.5C (mean 5
21.9uC) below Tair (mean 5 22.7C; range 16–28C).
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Tb = Body Temperature
Tair = Air Temp
At least for these Hognoses, basking is important.
Quote:
Single environmental temperature measurements
often explain only a relatively small amount of Tb
variation in snakes (Peterson et al., 1993). For example,
ground surface temperature explained less than 50%
of Tb variation in H. platirhinos in Canada (Cunnington
et al., 2008) and Tair explained only 37% of Tb
variation in our Arkansas study. Contributing to the
unexplained variation between Tbs and single environmental
temperature measurements is the common
temperate zone behavior of basking (Peterson et al.,
1993). Our observation of elevated Tbs in H. platirhinos
that were tightly coiled and fully exposed to solar
radiation support the notion that basking was
occurring. These observations suggest that basking
plays an important role in the thermal ecology of H.
platirhinos as previously suggested by Platt (1969).
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(emphasis added)
If you take the highest body temperature above air temp (11.7C) and add that to the highest air temp (29C) you get something like 105F. I
highly doubt these guys were in that range. We're talking about the extreme tip of the bell curve.