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Sat, Aug 12


Location is TBD

Be a Community Scientist!

Join the bat roost counts and contribute to new urban biodiversity research! This is an HFAC group booking with the Community Science program of the Natural History Museum, Los Angeles.

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Be a Community Scientist!
Be a Community Scientist!

Time & Location

Aug 12, 2023, 6:20 PM – 9:30 PM

Location is TBD

About the event

Join the bat roost counts and contribute to new urban biodiversity research!

Date: Saturday, August 12, 2023

Location: Duarte

Time: 6:20pm-9:30pm

Cost: Free (please keep reading)

Age: 10+

Your participation will help scientists understand urban bat populations, locations, how they react to human disturbances like noise and light pollution, and prepare conservationists to respond to the spreading threat of white nose syndrome in case it reaches Southern California.

You’ll be part of a team of community scientists doing field research, counting bats as they depart from urban bat roosts under freeway bridges and along the Los Angeles and San Gabriel Rivers. This information will help understand a little-studied part of bat research: bats in the city. 

Join the Bat Roost Counts and get a close-up look at nature in L.A.!

More Info:

Our HFAC group will be together at one of the two largest roost sites. The Duarte roost sit is perfect for those who are new to the roost counts. It's a much more accessible location and CalTrans biologists frequently join for talks about how they study and protect bats in urban infrastructure Even younger kids may be able to join us at this location and bat activity is pretty consistent. (Email us if your child is below the age of 10 and can sitquietly to count bats throughout the schedule - see below)

The Bat Roost Count is a community science project led by Miguel Ordeñana and other bat scientists where teams of community scientists watch bat roost sites—where bats rest during the day—to count how many emerge as dusk drifts into night. The project currently focuses on the L.A. River, San Gabriel River, and other locations in LA County. Every year, the first count is timed around the birth of bat pups, and the second count happens when these pups take flight to compare what roost numbers look like pre-pup and post-pup season.

Counting these bats gives biologists, policymakers, and activists important information about bat populations and activity in the city. While community scientists count, researchers take readings of the ultrasonic calls happening outside our human range of hearing using bat detectors. These devices record their calls which are later matched up to species, giving even more crucial information. Learn more about the Bat Roost Count below!

Interested? Please read these Important Notes:

*This is a free event. Which also means it is easy to sign up and unfortunately easy to not show up. We only have 16 spaces. Please let us know if there is any reason you will not be able to make it after your register.

*You will receive an email with all of the information that you will need, after registration, and before the event!

*Please, only 1 adult per child so we can invite as many students as possible. OR - drop-off your student with an HFAC educator.

*A mandatory video will be sent to you that must be watched before coming to the count.

Still Interested? Keep Reading!


  • 6:20 PM Meet your group at the location sent to your email for a review of how to count bats and to get your equipment (clicker counters and high visibility vests).
  • 7:00 PM Walk to the bat roost location (walking time varies per roost site).
  • 7:30 PM Group members take their positions around the roost to survey the bat roost from different angles.
  • 8:00 PM Sunset is when the bats come out! Time to start counting and recording echolocation calls.
  • 9:00 PM The bats have left their roost for the night. We'll regroup, share our bat count numbers, and walk back to our meet up location.
  • 9:30 PM End of the Saturday August 2023 Bat Roost Count! Click here to join us for Sunday!

What to Bring: Sturdy, closed-toe shoes that you don’t mind getting wet Warm layers Flashlight or headlamp Water and snacks Insect repellent *If you have trouble standing for long periods of time please bring or request a folding chair.  Important to Know: There are no bathrooms at the roost sites, please use the bathroom before arriving. The roost counts start during daylight and go into evening hours. Please make sure to wear layers to stay comfortable for the entire event. You will get another email from us closer to the roost count date with more information.

Liability Waivers must be signed by each participant at the location, before heading out for the roost count.

Questions? Email us at

Thank you for your interest in participating in this awesome opportunity to take part in community science!


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