Tracking the nightly emergence and migration of millions of bats across Central Texas using NOAA NEXRAD weather radar — since 2011.
in the Significant Bat Area of Central Texas
Quantifications are calculated from a snapshot of maximum density, unless noted as emergence totals.
subtract 5:08 hours for CDT of flights — 0:08 is about 7:00 pm CDT
Check out our Congress Avenue Bridge page for the latest Congress flight times and viewing tips.
Storms out W and in the S, storms over SanAntonio heading N up US281, Scattered storms over Canyon Lake & Wimberley & from WellsBranch to LibertyHill heading N, Frio 23:38, DavisBlowout 23:48, Chiroptorium 0:04, Stuart 0:08, rain over Congress at 0:22, SanMarcos SMCenterpoint Bracken SCUCISD SchertzClemens Seguin 0:28, McNeil 0:32, SanAngelo 0:38, Congress 0:42, NLamar 0:42, FosterRd 0:46, GrapeCreek 0:52, other flights suppressed or readings confounded by weather
Above video from the evening of July 3, 2013 showing a seabreeze front from the SE and bats emerging from Central Texas roosts to feed on insects pushed along by the front.
When millions of bats emerge from a roost, they show up on weather radar. Austin Bat Refuge has been studying this phenomenon — called aeroecology — since 2011, tracking the nightly emergence patterns of bat colonies across the Significant Bat Area (SBA) of Central Texas.
Our data covers an enormous region — from San Angelo in the west to Round Rock in the north, New Braunfels in the south, and Del Rio in the southwest. This area includes dozens of known bat caves, bridge colonies, and migratory corridors.
The radar images capture what the naked eye cannot: the sheer scale of bat movement across the Texas sky, night after night, season after season.
We use the same weather radar network that forecasters use to track storms. When bats emerge in large numbers, they create distinctive "bloom" patterns on the radar — expanding rings of biological targets rising from known roost sites.
Each night during the active season, we review radar imagery centered on the Congress Avenue Bridge and surrounding Central Texas colonies. We document emergence times, colony sizes, flight directions, and weather correlations.
Our written archive spans over 1,000 individual nightly reports since 2021. This longitudinal record is invaluable for understanding how bat populations respond to climate change, urban development, and natural variability year over year.
Every donation of every amount makes a difference.
Donate to Austin Bat Refuge →