Radar Central Texas SBA

Fall Migration Devil’s Sinkhole and Frio

Here we see what looks like the fall migration of Mexican free-tailed bats from Devil’s Sinkhole and Frio caves in Central Texas.
A 17 deg F drop in temp at dusk along with a 26 deg F drop in dew point seem to be the trigger.
We see them travel 100 miles SSW to the irrigated fields of Los Alamos, outside of Allende, Coahuila before they disperse.
They traveled about 116 miles in two hours, not the world speed record for mammals (99 mph) that the Frio bats hold, but not too shabby (58 mph).  They seem to be headed toward Cueva de la Virgen in Coahuila, a cave historically known to hold 350,000 Tadarida and 10,000 cave myotis.  We’d love to know if anyone is monitoring numbers at that cave and whether there is a big spike in numbers today and for how long.  If numbers surge there, will they stay all winter, or will numbers wane as they move further south?
Austin meteorological conditions at emergence are in a chart below the video.

fall-migration-devils-sinkhole-meterological-conditions

Posted on , updated on by The Refuge

Our radar video on the Today Show.

The Today Show came to visit Congress Ave Bridge and Bracken Cave for a story on Bat Tourism.

Featured is our Mexican free-tailed bat Freida and included is our radar video of the Bracken bats.

Too bad they didn’t credit us for either one of these!

Posted on , updated on by The Refuge

Shoal Creek Conservancy Bat Walk

We had a great time last night conducting a Bat Walk to mark the third anniversary of the founding of Shoal Creek Conservancy, here in Austin.
Bat fans showed up on the second night of cool weather to see if bats would fly from under the 9th St. Bridge in Duncan Park.
Though the cool weather felt great to us after a long extended hot summer, the bats were snug in their expansion-joint crevices under the bridge and did not want to drop out into the cool night.  The temperature had dropped to 43 degrees F the previous night and that night’s dew point of 47 F promised another cool night ahead.  Since fewer insects fly below 50 F, they must have decided to conserve their energy budget and stay snug in the roost.  Here’s a thermal imaging snapshot of the crevice we inspected.

thermal image crevice 9th St. Bridge Duncan Park

Those are bat bodies showing white and their reading was about 88 deg F on the outside of their fur.  Their body heat kept the crevice nice and warm, 82.6 deg F here next to the bats in this snapshot, 15 degrees warmer than the blue-colored bridge outside the crevice.  It would take a lot of snuggling to re-create all that warmth, so perhaps they just hunkered down to wait out the cooler nights.  Low temps will be back in the 60s for the next two weeks, so I think they made the right call.

Great group of people at Shoal Creek Conservancy; we’re so happy there is a unified voice to speak up on behalf of beautiful Shoal Creek!
Thanks to all who came out to hear our talk and watch our radar images of Central Texas bat activity.  Next year we’ll unveil the new SonoBat Live and if we get a warmer night, we’ll all be able to see real time sonograms of the echolocation calls of flying bats.

Posted on , updated on by The Refuge

Seabreeze & North Front

Great night for Central Texas bats as a strong seabreeze pushes moths toward the Hill Country while a North front brings reverse migrating moths back from the northland, making a smorgasborg for Mexican free-tailed bats fattening up for their own migration south at the end of the month.  This year’s pups are packing on the grams preparing for their first big journey.  Their is a lot going on in this video as the Hill Country roosts are perfectly situated to take full advantage of both fronts.

Here’s the Congress Avenue Bridge bats that same night going with the seabreeze to the NW, to feed on moths pushed along on the leading edge of the front.

Posted on , updated on by The Refuge

Hungry Bats

14Apr2016 UTC       click at left for video

Frio & Bracken bats cover at least 40 miles in an hour in this video (link above left).  Mexican free-tailed bats are capable of flying over twice that fast in unassisted flight.  The location of both caves at the edge of the Texas Hill Country (dark grey at top) gives the bats immediate access to the agricultural fields that attract their favorite food, the corn ear-worm moth.
Could be as many as ~8 million at Bracken and ~6 at Frio, and this is just a snapshot in time, not the whole emergence!
Stuart bat cave and then Rucker emerge later at top left of video.

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Posted on , updated on by The Refuge

Free Pest-Control Service for the Winter Garden

Frio 28Mar2016 UTC        Click to left for video

Last night, what looks like about 3-1/2 million bats emerged from Frio Bat Cave and headed south toward the Winter Garden area south of Uvalde, providing free pest-control service to farmers in a large area west toward Bracketville.  Hope they stayed clear of the turbines at the wind farm.  Anybody doing a count this morning?

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Posted on , updated on by The Refuge

Rucker Bat Cave & Fern Cave, early spring

Rucker & Fern early spring 20 MB      click link to left for video

Rucker Bat Cave (TX8) in Edwards County Texas is always active this time of year, as Mexican free-tailed bats make their way back into Central Texas. This reflectivity represents many hundreds of thousands of bats. Were happy to see Fern Cave (TX6) in Val Verde County with a large emergence also, we have been seeing fewer bats there than in years past.

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Posted on , updated on by The Refuge