Hold Your Judgment, These Marin Bats Are Just Misunderstood

Wildlife biologists in Marin County are in the midst of a study that will help conservation efforts for a still somewhat mysterious creature: bats.

Gabriel Reyes, a biologist with the United States Geological Survey, says there are some common misconceptions surrounding bats. They've been described as flying rodents, and thanks to Hollywood, some may even think of them as fearsome critters.

“They're actually not [flying rodents],” says Reyes. “They're more closely related to the common ancestors of camels and whales. They're really nothing to be afraid of. I think they're all adorable.”

I have to admit that I also think they’re pretty cute. But seriously, Reyes says bats play an important role in our ecosystem. They’re the primary consumers of nocturnal insects like mosquitoes and other agricultural pests. So, you can think of them as winged exterminators.

“Without bats gobbling up bugs all night we would be spending way more money on pesticides, and that can have other impacts worldwide,” says Reyes.

They’re also plant pollinators and seed dispersers.

The next time you drink a margarita, thank a bat — we wouldn't have tequila without bats pollinating agave plants.

But there’s a lot more we don't know about bats, such as what the population or habitat is like in Marin. So the USGS, along with conservation group One Tam, set out to fill those data gaps last year. It hasn’t been easy.

"They're incredibly challenging to study,” says Reyes. “They're silent. They fly around at night. They live in really hard-to-access places.”

But things like tiny radio transmitters and ultrasonic microphones help. The first step of the study was to set up acoustic monitoring devices, or bat detectors, at 36 sites throughout the county.

So far, the survey has picked up the calls of 13 bat species in the county. One Tam’s community science program manager, Lisette Arellano, says that number speaks to the incredible diversity of bats in Marin.

"We have something like 17 terrestrial mammal species that are bigger than a squirrel,” says Arellano. "When you compare that 17 to the 13 flying mammals, it just gives you some context as to how diverse the mammal community is when it comes to bats."

Many of the bats found in Marin are tiny. Some are as small as a thumbnail and are about as heavy as a nickel. Heftier species weigh close to five nickels.

The second step of the study was to actually capture the bats through mist netting, a fine mesh net that bats fly into. Capturing the bats allows biologists to study their ecology and attach radio telemetry tags to track their movements and roosting habits.

Reyes says the tags’ batteries last about two weeks and naturally fall off the bats in about the same time.

The study is ongoing, and both Arellano and Reyes estimate the monitoring will continue for the next couple of years. Arellano says results will provide some much needed baseline data on bats, so that land managers like One Tam can make decisions on how to best preserve them and predict which diseases, like white-nose syndrome, might affect the population.

That information will also be added to a larger database that will eventually increase our understanding of bats — not only in Marin County but in all of North America.