Environment

These nighttime insect eaters will keep you from going bats

Are our local bats at risk of getting white-nose syndrome?

Corky Quirk, the Yolo Basin Foundation program coordinator, explains the impact of white-nose syndrome to the Yolo Causeway bat population at the Yolo Bypass Wildlife Headquarters in Davis, Wednesday, July 11, 2019.
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Corky Quirk, the Yolo Basin Foundation program coordinator, explains the impact of white-nose syndrome to the Yolo Causeway bat population at the Yolo Bypass Wildlife Headquarters in Davis, Wednesday, July 11, 2019.

What flies at night, can eat its own weight in bugs, and is the fastest mammal on Earth? Bats!

Specifically, Mexican free-tailed bats – 250,000 of which make the Yolo Causeway their home during the summer, according to Corky Quirk, project coordinator at the Yolo Basin Foundation. These little creatures live in the inch-wide parallel expansion joints underneath the bridge, sleeping there during the day and leaving to hunt at night.

The Mexican free-tailed bat can fly up to 100 mph, and they are one of the most common bats in Sacramento, Quirk said. A nursing or pregnant female eats its own weight in insects every single night.

“They are our No. 1 nighttime insect control, natural pest control,” Quirk said.

The Mexican free-tailed bat mainly eats moths such as the corn earworm moth, coddling moth and armyworm moth, all of which are major agricultural pests. Another species common in the region is the big brown bat, which eats beetles that attack crops and trees.

These furry pest-eaters save farmers billions of dollars a year in reduced pesticide use and crop loss, according to Quirk.

Bats are also extremely important to the Sacramento Valley in stopping the spread of diseases such as the West Nile virus.

“We live in an area with rivers and wetlands, so our insect populations are large and would be even larger if we didn’t have the high percentage of bats we have living around us,” Quirk said.

Quirk, 56, loves bats.

“They’ve taken over my life,” said Quirk, who has been working in bat education and conservation at the Yolo Basin Foundation since 2004. Throughout the summer, she takes groups out on “Bat Talk and Walks” to see the massive swarm of Mexican free-tailed bats fly out from underneath the Yolo Causeway to hunt insects for the night.

Quirk handles several rescued bats that she uses for educational purposes, but it is illegal to keep them as pets. It’s important to remember that “wildlife is wild,” she said.

The recent arrival of a fungus that causes the deadly white-nose syndrome in California has alarmed bat conservationists in the state. The fungus leaves a dusting of white on their noses, skin and fur, and millions of bats have died from the syndrome since it was discovered in New York in 2006. In some areas where the fungus has spread, up to 90 percent of some colonies have died.

“It’s a huge problem, and it’s terrifying,” Quirk said.

The little brown bat species is the most vulnerable to the fungus. Not much is known about where they migrate to hibernate during the winter, and if they die in the winter, they will not return to the area, Quirk said.

A little brown bat can eat as many as 10 insects a minute, and they hunt for as long as four hours every night. These bats are the ones that eat tiny pests such as mosquitoes and gnats.

Since white-nose syndrome is most lethal to small bats that hibernate for a long time, Quirk predicts that some of the species common in the region will not be as vulnerable. The Mexican free-tailed bats, big brown bats and pallid bats that live in Sacramento don’t go into true hibernation — rather, they go into a state called “torpor,” where they slow down their body without actually hibernating.

The species that stay in the area year-round are also likely to not succumb to the disease. Bats will hunt as long as it’s above 40 degrees and not raining, Quirk said, preventing them from starving to death while trying to fight off the disease.

Though it’s a mystery how the fungus reached California, Quirk says it was most likely humans. The best way for people to prevent the further decimation of bat populations is to stay out of their habitats and to clean their shoes and clothes before entering and after exiting caves, Quirk said.

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Jaimie Ding, from Scripps College, is a local news reporter for The Sacramento Bee with an interest in politics and international relations. She grew up in Vancouver, Washington.
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