Photo © 2005 Jim Jung and licensors. All rights reserved.

Bats

While many bat species migrate south like birds our rarest and most vulnerable bat species begin seeking caves, abandoned tunnels and buildings. As the nights begin to cool and lengthen (and insect populations begin to decline) bats seek out a safe refuge from the cold to sleep the winter away. Very occasionally one will turn up during warm evenings in December or February (which leads me to believe that not all bat species truly hibernate).

Caves are the refuge of choice for most of our bats which is why there is now a caving season for spelunkers (cave explorers). It runs from April 15th to August 15th and is designed to keep bats safe and undisturbed during their winter sleep.

Bats are tiny animals - no bigger than a mouse in most cases - and therefore have little room for fat on their tiny frames. What little fat they do possess will be just enough to carry them through winter to the first insects of spring - just enough and no more. Any disturbance of their winter hibernation - noise, the slight rise in temperature caused by a caver's passage, or light - is enough to rouse them from their winter slumber which causes their metabolism to rise and their consumption of fat reserves to increase dramatically. Should this happen too often, or if awakened prematurely, the bats will consume all of their winter reserves of fat before the first insects appear in the spring and the bats will starve to death. Such disturbances are suspected as one primary cause in the precipitous decline of the endangered Indiana Bat and similar species.

Photo by Jim Jung. All rights reserved.

Bats are extremely important predators of night-flying insects and are probably the principal predator of mosquitoes. A single bat can consume up to six thousand mosquitoes a night and a large colony can make serious inroads in their populations. Areas with high bat populations have correspondingly low mosquito populations.

So should you encounter a colony of hibernating bats anywhere leave as quietly as possible, disturbing the bats as little as possible and avoid the area until spring is well under way.

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