Bats in Winter

Bats in Winter
By: Carol Bunyard

Caring for Oklahoma's wildlife offers countless opportunities for learning more about the amazing biological adaptations of our native creatures. Such has been the case this year, when WildCare has over wintered bats for the first time. Two red bats (Lasiurus borealis) and five evening bats (Nycticeius humeralis), all females, have spent the cold months in warmth and comfort while awaiting the spring thaws. The red bats, being a solitary species, are each housed in separate cages, while the evening bats, being a colonial species, are housed together. Twice a day all seven bats are hand fed a special blend of mealworms, waxworms, food supplements, and baby food.

Little is actually known about the winter habits of our native bats. It is believed that red bats may hibernate on the ground in leaf litter. Some evening bats are thought to migrate to warmer climates and remain active year round, while others in the northernmost parts of their range are believed to hibernate in buildings and under loose tree bark.

During the warm months, when we typically receive bats, they have a very high metabolic rate. They consume a comparatively large amount of food each day in order to maintain that metabolism. It became quite obvious, particularly in the red bats that, as the days grew shorter their metabolic rates were slowing down. The amount of food they needed at each feeding diminished significantly, and for a period of about a month, one of the red bats required only one feeding per day. Though none of the bats ever went into deep torpor (which has been known to happen with bats in captivity even when they are maintained at a constant temperature), their levels of activity dropped to almost none, and their body temperatures dropped to the point that they were cold to the touch and had to be warmed prior to each feeding. The evening bats preferred to roost in the cooler area of their cage.

Now that the days are getting longer once again, the bats' activity levels and appetites are showing a proportionate increase. They are starting to show a preference for the warmer sections of their cages. They are much more alert and aware of their surroundings. They seem to quiver with expectant enthusiasm -- as if they anticipate the coming of spring and their release.

Director's Notes
Carol has volunteered over 1,000 hours to Wildcare in addition she has passed the international wildlife rehabilitation class and has taken 2 - 1 week long intensive training classes "Bat Boot Camp" with Bat World.