Surprisingly large blooms from Fern Cave Stuart Cave and Old Tunnel at 7:30 pm last night. Each bloom represents many hundreds of thousands of bats.
We expect big blooms from McNeil Bridge on warm winter nights, but in our experience it’s unusual to see such large blooms from the other roosts.
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Close to a million bats emerge from Old Tunnel on the evening of January 16, 2017. This is the first time they’ve showed up on our radar since New Year’s Eve.
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!
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.
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.
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.
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.
For the Congress Avenue Bridge bats, the scariest time of year is 4th of July, when the annual fireworks display takes place just a few hundred yards to the east of the bridge. The bats are emerging at dark this time of year, exactly at the time the fireworks start. The emergence peaks around 9:30 pm this time of year, just when the fireworks are reaching their crescendo, seen in yellow on the left.
We normally see greatly reduced emergences for a number of days after the 4th.
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.
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?
Bats are Back 16Mar2016 UTC HD (Click on link to see video)
The bats are back at Congress Ave Bridge in Austin!
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.