Naturespeak A naturalist's view of the world

January 27, 2014

Bat in a Can Can

Filed under: Uncategorized — wykes @ 11:50 am

In short, a bat in a can can a.) revive itself from deep hibernation and b.) relocate to a better location on its own.  I received just such a canned bat last week and can now attest to the veracity of these two statements. A good friend called me last week after his attic water pipes froze and burst. The water flowed down through several levels in one of his rental units and melted a portion of the ceiling of the upstairs apartment. He didn’t call to ask me to fix it. I am a duct tape type of guy and he is a professional handyman.

Apparently the damage upset one the residents and he thought I might be interested. He was right. The resident in question was a bat (the apartment was un-occupied by humans at the time). It apparently came down into the room seeking a way to get the heck out of that unfriendly joint. Not knowing what to do with it, but not wanting to kill it, my friend coaxed the little beast into an old coffee can and put a loose plastic bag over the top to secure it. It was now in his unheated breezeway at home, he said, and was mine if I wanted it.  Of course, I did.

I didn’t actually connect with my friend, and his bat, until three days later (it’s a long story about a missed phone message etc. etc.) The canned creature was still alive when I stopped by to pick it up. A peek inside revealed a Big Brown Bat. It was torpid (sluggish from hibernation) and barely took notice of our probing fingers. We laughed over the real need to cover the top of the can – after all it wasn’t likely to go flying off in 10 degree weather…right?  So, I brought the frozen orphan home to my un-heated back porch and pondered its future.

My plan was to wait until the temperatures rose up into the 30’s and let him go. It is not unusual for Big Brown Bats to fly about in mid-winter seeking new shelters (especially when their old ones suffer from busting pipeitis). Unfortunately the prospect for the coming week was for a continuation of the arctic blast with no January thaw in sight.  That first night was to dip into the single digits and I worried about my little charge. For a second I thought about popping him into the frig but could not muster the ability to tell my wife, although I’m SURE she’d understand but… As it turned out the issue resolved itself without my sleeping out on the couch.

The bat was gone by the next morning. As the temperatures plummeted, he scrambled up the side of the can, pushed aside the bag cover and flittered away. Although I believe he secreted himself in one of the many niches and gaps between the house and the porch, he may have found exit to the outside world through numerous egress points (it is a very unfinished, as well as unheated, porch).  In other words, Big Browns are not helpless refrigerator magnets when in hibernation mode.

Cave dwelling bats need the stable 50-some degree environs found in caverns while B.B.B’s have adapted to shifting winter temps. Cave bats tend to cluster while Big Browns usually go it alone. They are very tolerant of cold and are one of the few bats that can afford to hibernate in drafty northern attics.

When entering hibernation mode they dramatically lower both body temperature and metabolism to reduce their energy requirements but oddly enough rarely stay in such a state for more than 3 or 4 days at a time. They wake themselves frequently in response to changing temperature and as a matter of habit. At least one study showed that these wide-awake periods last 5 hours on the average – which allows enough time to shift about or re-locate if necessary. One study even proved, and I am grossly summarizing here, that if a bat stays in a torpid state for too long it will get “stupid.” They need to wake up and restore their “synaptic synapses.”  I’m not sure there is a human parallel to draw here, so I won’t attempt it.

In retrospect it is amazing that my bat survived its multi-day sub-freezing can experience at all. The ideal hibernation temperature for such a creature ranges between 37 degrees – 68 degrees F. The air temperature has to be above freezing for this hibernation thing to work. When ambient temperatures dip below 32 degrees F the bat can raise its body temperature, wake up, and move or it can increase metabolism, stay in hibernation, and make up the difference. Either choice burns up fat stores but trumps the alternative which is freezing to death.

It’s a good thing that I took a few photos right away when I initially brought the Big Brown Bat inside. I was planning to try for a few better shots on the following morning. The bat, however, obviously had better plans. Once again I am humbled by what nature knows and I don’t.

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