Why this biologist is leading night walks to hunt for bats along the LA River

The sun was just starting to set as about a dozen people gathered at Elysian Valley Gateway Park along the L.A. River.

We’re here tonight to chase bats with the help of Joey Curti, a bat biologist and postdoctoral research fellow at UCLA’s La Kretz Center for California Conservation Science. It’s part of a two-part bat educational series organized by the Theodore Payne Foundation.

“They do a lot of things that I think people don’t realize,” Curti said. “And really in the pest control services that they provide for us, they prevent a lot of human illness. So they’re kind of vital for the ecosystem. And I don’t think we realize that because they’re flying around at night and we never see them.”

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As the bat walkers assembled around Curti, he showed off an ultra-sonic microphone that would help them feel the presence of the bats even if they couldn’t spot them with the naked eye or ear.

“Each bat here in the city emits a unique acoustic signature, just like a bird will sing and have a unique song, bats do the same thing,” Curti said.

Joseph Curti educates bat walkers.

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Robert Garrova / LAist

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As the bat students embarked along the paved L.A. River path, occasionally dodging nighttime cyclists like real-life frogger, Curti held up a tablet connected to his microphone that displayed visualizations of the sounds the bats make — kind of like the popular Merlin app you might use to identify birds in your neighborhood.

It’s not long before we come across our first species, a Mexican free-tailed bat.

A Mexican free-tailed bat.

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Joseph Curti

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(Note: While the bats pictured in this story were detected on acoustic devices — and sometimes briefly seen flying around — no bats were handled during the bat walk event.)

Curti explained that we have as many as 21 species of bats here in L.A. Sometimes on these walks he comes across four or five in one night.

“I think a big majority of that is the fact that we have such a diverse vegetation community here,” Curti said. “We have these big mature trees which can be roosts, but also support a lot of insects."

Coast live oaks are “incredible” trees that support bat diversity in our region, he added.

As the long train of bat walkers pressed on, we came across another species. The acoustic detectors started clicking like space aliens talking in the night.

“Wowww...” the bat walkers said in awe.

“It’s right overhead right now,” Curti said, holding his acoustic-detecting instrument.

This time it’s a Yuma myotis bat, which Curti said weighs about 5 grams — the weight of two pennies — and is about 3.5 inches long.

A Yuma myotis bat

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Joseph Curti

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(A note from the bat experts: "All bats [pictured in this story] were handled by trained wildlife biologists with appropriate state and federal permits and rabies vaccinations. To reduce the risk of harm to yourself and to bats, please only handle wildlife if you are trained and permitted to do so!")

“It’s almost certainly just skimming the surface of the water, getting things like mosquito larvae,” Curti said. “Yuma myotis, because they’re such little squirts, they eat a lot of really small prey. Which means they tend to focus a lot on mosquitos... they’re really pulling their weight to protect us.”

‘Deserving of our protection’ 

Curti said he hopes these walks will educate people about the diversity of species flying right overhead. And how vital they are for the ecosystem, not just keeping down mosquito populations, but pollinating our crops and plants.

Curti didn’t have to work hard to convince bat walker Ed Rubin of the importance of bats. Rubin said he’s been into the bats since 1985 and is up tonight from San Diego for this walk.

“I’m a bit of a bat fanatic, Rubin said. “I try to tell as many people as I can about the wonders of bats. Because they are deserving of our protection.”

One of the best things you can do to help out bats in your neighborhood? Curti said plant native plants that attract a diversity of bugs that bats like to eat.

Curti points to a planting palette for bat-friendly gardens from Bat Conservation International, as well as a list of plants pollinated by moths compiled by the Theodore Payne Foundation. And since not everyone has a backyard, Theodore Payne Foundation also has a list of native plants that can thrive in container pots.

Curti is scheduled to give a talk for the Santa Monica Bay Audubon Society on Nov. 4.