Radar Congress Avenue Bridge

Friday the 13th

We got lucky on Friday the 13th and had lovely weather for our education table at the Bat Viewing Area.
We shared the wonders of bats with scores of out-of-towners.
We so enjoyed meeting Sonia from Austria, Anne from France, Ali & Xav from Paris, and that group of impressive women in town for the Anthropology conference, from Virginia, Canada, the UK and Cyprus.
What fun!  Thanks for visiting with us y’all!

We hope the bats were as lucky as we were!  We at the Bat Viewing Area all watched on live radar as  a lovely Seabreeze pushed insects toward the Hill Country and the Bracken bats foraged along the front.  But then things changed.
The lovely Seabreeze turned into wicked storms from the northwest.  Davis Blowout, Huber Limestone Mine, McNeil Bridge, and Congress Bridge bats all appeared to have been caught out in the storms.  We hope they sheltered at McNeil to escape the worst of it.
Bats caught in hailstorms frequently experience broken wing bones from the hail.  Guess we’ll see how many bats are found by humans and brought to us today. Bless their brave little hearts!

 

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Pre-Migration Activity

Lots of Central Texas bat activity on a chilly evening. Devil’s Sinkhole, Old Tunnel, and Huber really show up strongly because of their more isolated locations.  Still a strong flight from Congress, so our newly released bats have plenty of company.

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Fire the Lasers!

Free-tailed pup trying on his scary face for Halloween.  We’re not buying it – still way cute!
Best Insta-replies?
From pink_1101floyd “Fire the lasers!”
From 747mandi “Game face!”

Austin bat talks presentations outreach education programs Congress Avenue Bridge bats

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Ebb & Flow

Huber Limestone Mine bats left their Marble Falls roost and headed towards the Blackland Prairie last night, arriving in Austin and Rock Rock around 11 pm.  There is apparent comingling of the colonies as they hunt, suggesting considerable ebb & flow between the roosts on a regular basis, either nightly or during shifts in short-term weather patterns.

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Stable cooler temps = better flights at CAB

Stable, cooler temperatures after the storms led to the first great emergence in over a week, last night at Congress Avenue Bridge.
Here we see about 1-1/2 million Mexican free-tailed bats on Doppler radar as they head out to the agricultural fields to forage for crop pests.
Winds from the NE at emergence sent them to the SSE about 18 miles past Mustang Ridge along Cedar Creek.
We frequently see them head on a broad reach to the wind, taking advantage of the free ride while knowing the winds normally die down by the time they want to return.

austin bat presentations education outreach talks

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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.

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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.

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Doppler radar of Congress bats on the full moon

Congress Ave Bridge bats on the full moon

CAB bats head out to forage in the pasture land and agricultural fields between Bastrop and San Marcos on a full moon night.
They don’t seem to be deterred by the full moon, they are flying in big numbers even as the moon rises, although more seem to be staying within the city limits than usual.

One would think that Mexican free-tails would be lunar phyllic, since they feed in wide open spaces away from tree-loving owls and the moonlight might even allow them to better locate prey visually, before kicking in their echolocation when they get within range.

At this time of year (even on a wet year like this one) there is likely less insect prey in the agricultural fields and the bats are eagerly awaiting the reverse migration of the Corn Ear-worm Moth that usually starts in late September.  CEM return south in the fall because their pupae can’t overwinter up north.  Mexican free-tailed bats depend on this reverse moth migration to put on weight prior to the bats’ own migration south in late October.

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The Bats are Back!

Bats are Back 16Mar2016 UTC HD   (Click on link to see video)

The bats are back at Congress Ave Bridge in Austin!

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This video from last night shows 3 or 4 separate flights from the bridge before a north front sweeps in, taking most of the bats along for the ride.
The last few years the bats have made sure to be back for the South by Southwest Music Festival.

The viewing is great these days, they’re coming out well before dark.

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