A new study has revealed the rare hibernation habits of hoary bats. This is significant as bats are known either for migratory habits or hibernation habits.
Here one bat species, Lasiurus cinereus, is showing both behaviors and that is something unusual.
Known to travel hundreds of miles, these bats - one of the largest in North America - have an average 5-inch length. Their frosted fur gets them the name hoary bats. They are mostly spotted in the redwood forests of California.
The unique hibernation habit was unveiled by researchers attached to the Pacific Southwest Research Station of the U.S. Forest Service.
Published in Scientific Reports and coinciding with National Bat Week, the report explains the newly discovered hibernation and seasonal movements in hoary bats.
Hibernation Came As A Surprise
"It's commonly assumed that species that migrate do so to reach areas that allow them to continue feeding and remain somewhat active throughout the winter," said lead author Ted Weller, an ecologist with the Forest Service.
Noting the winter hibernation habit of hoary bats has been a surprise, the author said the observation efforts lasted for two years.
The test was conducted on a few bats at the Humboldt Redwoods State Park in California using GPS devices to tag some bats.
Another batch of bats were tagged with data loggers that included a light sensor to measure the levels of light and an accelerometer that recorded the bats' activity. Ambient temperature and the bats' body temperature were also measured. The data would indicate when bats were active or inactive and allow researchers to comprehend how the bats responded to the changing seasons and weather conditions.
Two bats were recaptured after a month for data download. One GPS-tagged bat showed an expected behavior of a maximum of 4 miles for a one-day trek from where it was first captured. The second one had multiple single-day treks that stretched to 45 miles to its credit.
Several months later, a third bat was captured, and it was what surprised the researchers the most. The bat covered 600 miles of distance to touch destinations like southern Oregon, interior California and the Nevada-California border before coming back to interior California.
Weller said it is hard to say what made it travel like that.
The hibernation habits were illustrated by the data loggers attached to the other bat group. Data from one of the recaptured bats showed inactivity and a cooler body temperature from November 2014 to April 2015, indicating that the bat was in hibernation during that period. The scientists are now attempting to link hibernation habits to the roosting habits of hoary bats.
"Hoary bats roost outside in trees as opposed to inside caves," Weller said and added that they can hibernate but may freeze doing so in their northern summer territories.
On the contrary, redwood trees offer them shelter, tolerable temperatures and a reduced risk of getting dehydrated due to lots of moisture.
The study also assumes significance in planning conservation efforts as the data on bats' migratory habits, movement, and habits during the cold season are very useful.
