Last night’s Congress Avenue Bridge info

12 May 2019
Flight time:  8:30 pm   Sunset 8:15 pm  Dark 8:45 pm CDT

Comments:  15 min after sundown ~639k  flew 14 miles SSE – Winds NE at 6 mph, Visibility 10 miles, Mostly Cloudy, Temp 73 F, Dew Point 58 F steady, Cloud Base 3420′,  RH 59% rising, Heat Index 83 F, BP 29.86 steady, bats visible until 9:03 pm under lights
Estimated numbers are derived from a snapshot of maximum radar reflectivity and will change nightly. Estimates may not reflect total numbers due to not all bats flying at the same time or flying low under the radar.  

Please be advised: Below the bridge at the south side bat viewing area, is best viewing when bats fly more than 12 minutes after sunset.
At those times, views from the top of the bridge consist of dark bats against dark water and/or dark treeline and many people do not notice them.
From mid-May until late July, viewing from the top of the bridge, or the north side trail bridge, can be disappointing!
At these times, the south side under the bridge is best as most bats will stream down the south shoreline to the east and you can backlight them against whatever light is left in the sky or against light from the city skyline.
Standing under the south side of the bridge after dark allows you to see the bats lit up by streetlights, while the bridge blocks the light from reducing your night vision.

Insider tips!  

Emergence predictions: 
The product of a decade of data collection (0ver 100 data points per night) and meterological forecasts to give you the inside scoop on emergence times!

Morning returns:
Don’t tell anybody, but:  If you arrive on top of the bridge at 30 min before sunrise on a clear summer morning, you’ll have the joy of watching the city wakeup as runners, rowers, egrets, cormorants, and herons  all zoom around in the cool, crisp, air!  And as you drink in this morning energy with its unlimited possibilities,  bats will be raining down like confetti as they return to their shady roost to sleep with their pups, leaving the heat of the day to mad dogs and humans.  If you look high in the sky (bring your binoculars) you’ll see Peregrine falcons circling over the bats, diving occasionally to try their luck.  They can’t catch these bats from behind in level flight, so they use gravity booster-jets. Some bats flee them straight down and dog-leg under the bridge, others drop in a fast zig-zag, but if the falcons are not close, most simply rain down like confetti in a wonderful display! A bat snow-globe!  If you follow one bat with binocs as it approaches the bridge, you can watch as it tucks its wings and follow it as it dives!  It’s a brilliant way to start a day in Austin, followed by a brisk walk to Barton Springs for some morning laps in the pool and a hike up the greenbelt.  Just thought you might like to share in just a little of what we call “the soul of the city”; you can thank us later!

 

Austin Bat Refuge is funded solely through donations and grants.
We provide care for injured and orphaned bats, education outreach, and conflict resolution.
We have been the sole bat rehabilitators in Austin for twelve years.
Lots of people talk about Austin’s bats, please join Austin Bat Refuge in actively caring for them!
Ask how you can help at our info table on Friday and Saturday nights at the south lawn Bat Viewing Area

Last week’s flights

Viewing tips

• Best viewing is from mid-March to early-May & also from late-July through September.
  • Bat flights from early-May through mid-July are usually after dark.
• There’s a denser, more consistent stream of bats at the south shoreline (farthest from downtown).
• Below the bridge at the Bat Viewing Area is better for a close-up view. Our work with The Trail Foundation has enhanced this view by removing tall invasive shrubs and replanting with bunch grasses and acanthus, which should provide great hummingbird activity before dark, while not blocking your view of the bats flight!
• Below the bridge on the south side, is better when bats fly more than 12 minutes after sunset.
• At the Bat Viewing Area, you’ll want to be down by the fence at the shoreline when the bats fly for a close-up view.
  • But don’t forget to check over the treeline, to see if bats are going to altitude; this can be spectacular!
  • When you leave the bat viewing area, make sure to pause to watch bats flying out the south side long after dark.  This is an intimate, fun experience that is similar to what bats did when they first arrived at Congress. It was made possible by our meeting with various city agencies to arrange for removal of the tall invasive shrubs that had blocked the bat’s flight path.
  • We also had the City control the poison ivy that had grown on shrubs overhanging the trail.
• For families with children and/or pets, underneath the bridge is best (no traffic worries).
• On warm nights, it’s easy to see streams of bats heading down the river from the top of the bridge if flights start less than 12 minutes after sunset.
• It will get dark earlier if cloudy.
• “Scout” bats, also know as “Light Samplers,” will fly out before the main emergence.
  
• When bats fly after dark, great viewing can be had by going under the shadow of the bridge.  Street lights illuminate the bats, but you won’t be blinded by those same lights.
  You’ll see way more bats standing in the shadow than one foot over looking up into the street light glare.

General Congress Avenue Bridge info

• Bats entered slacker season when they sleep late and emerge at dark on April 28, 2019
  Spring return migration started around 09 Mar 2019 but cold weather suppressed flights until 19 Mar 2019.
• Colony seemed to be at full strength around 20 Mar 2019  after surges of bats pulsed through the area.
• Typically we start to see spring migrants in early March, with Congress reaching full size by the second or third week of March.
• We appeared to have up to 45k bats overwintering this year. They seemed to come and go from the bridge to seek shelter in heated, poorly insulated buildings during cold spells. If you have bats roosting in your roof, then you probably have heat leaking from your building envelope into eaves and attics.
  No charge for the Free Energy-Auditing Services! Just the Congress bats’ contribution to Combat Climate Change! 
• Fall migration appeared to have started 07 Nov 2018 and continued 09 Nov 2018.
• Surges of migrating bats pulsed through periodically throughout Nov.
• Congress bats returned from Mexico on 06 Mar 2018 last year and gave birth in the first week of June.
• Last year’s pups started flying 14 July 2018, we started noticing them at the bridge around 22 Jul 2018.
• The bats are generally with us through Halloween, then head south on the first strong cold front.

Our Congress Avenue Bridge is by no means the only bat roost in Central Texas.
Learn more on our Radar page.

Best viewing is at the end of August, when the pups have been flying for about a month and the drought has set in. And CONGRESS IS ON FIRE!
But bats don’t burst into flames when exposed to the sun’s rays,  they just take on a beautiful glow! (Video below)

Video below shows a rehabilitated bat getting released back at Congress Avenue Bridge.
He was rescued by Kyndal of Austin Bat Refuge and the UT Animal Make-Safe program.

Austin Bat Refuge volunteers assist The Trail Foundation replant the Congress Bridge shoreline – Shovels Up!

Friday Night Flights!

During the season (mid Mar to the end of Oct) please visit Austin Bat Refuge at the Bat Viewing Area under the south side of Congress Avenue Bridge.

We at Austin Bat Refuge revived and re-invented the long-dormant Information Program at the bridge and Austin Bat Refuge continues to provide information to the tourists several times a week.  We love meeting people from all over Texas, the U.S., and the whole world, as they come to witness this natural wonder in the heart of our city.  Please stop by and sign our Bat Journal, tell us how to say “bat” in your language!

Bat viewing etiquette

1. Never handle a grounded bat. Call Austin Bat Refuge immediately at 512-695-4116 or 512-799-8847.
2. Be kind, don’t shine bright lights.
3. Loud sounds or rhythmic clapping only serve to delay the flight even longer.
4. Keep drones at a distance; don’t get down in the stream of bats! (See City of Austin drone regulations.)

And now, a semi-tongue-in-cheek rant by an Austin Bat Refuge bridge docent:

Notice!

Due to public demand, we are hereby announcing that we have reset the Congress Avenue Bridge Bat Wake-up Call to 7 pm.
Bat Emergence Performances will now occur precisely at 7:15 pm and again at 8:15 pm.

This rescheduling has been enacted to ease public anger , when the bats personally offend visitors by not performing in a timely manner.  Adding insult to injury, these delayed performances seem to have been occurring regardless of the distances traveled by visitors to view the performance.

However, after negotiations held early this week, the bats have agreed that it’s well worth it, to put off giving birth and to sacrifice their maternity leave, in order to provide for a more predictable, family-friendly viewing experience, for humans.
So please help us get the word out about the new early evening Congress Avenue Bridge schedule.  Please note, however, that it is subject to change as soon as visitors pay for parking and get their families comfortably seated on blankets on the lawn.

In fact, as part of the negotiations, the bats have reserved the right to wait until all the cruise ships, tuna boats, paddle boards, water bicycles, kayaks, canoes, drones, helicopters, red lights, white lights, flash photographers, movie crews, and well …. people have gone away before they emerge.

While they admit that humans can be beneficial in that they scare away hawks, falcons, owls, and other predators, they are willing to take their chances and move to  other roosts if the above-mentioned shenanigans get even worse!

Development of the South Central Waterfront

World famous attraction, soon to be subject to intense development pressure
of the South Central Waterfront
Illustrative Buildout Rendering of the City’s SCW Master Plan is the multi-colored area in the rendering below
This Master Plan includes some nice ideas for viewing the bats, but the development itself could have a negative effect on the colony.
How can we help mitigate the effect of all this additional development?
Make the SCW a Dark Skies District
A synopsis of our suggestions follows with substantiating arguments below the renderings

1- Control lighting around the bridge
2- Control lighting along the south shoreline which serves as the bat’s commuting corridor
3- Require bat-compatible building standards in the SCW to minimize bat human conflict
4- Make Austin Bat Refuge a stakeholder in any development application and approval process
5- Incorporate an Austin Bat Refuge Education Center in the park
6- Use park maintenance policies that are sensitive to the bat’s flight path
7- Extend the downtown panhandling ban to the SCW District
8- Limit facility lease agreements in the immediate vicinity of the bridge to quiet daytime events
9- Limit the increasing violence of Fourth of July fireworks at Auditorium Shores – No Howitzers!

Here’s what we think are reasonable and necessary steps to preserve the iconic bat bridge that helps give Austin it’s Sense of Place.

1- Control lighting around the bridge
Increased lighting levels at the bridge could adversely affect the colony by interruption of circadian rhythms.  Dark Sky initiatives in the area around the bridge and avoiding light trespass on the roosts would ensure that the bats know the proper time to emerge to hunt.  The building closest to the bridge is envisioned to be an office tower.  This is preferable to residential use (with accompanying light at night and viewing balconies) but should also require lighting controls such as timers or electronically tintable glass in order to prevent increases in ambient light at night so close to the bridge.

2- Control lighting along the south shoreline which serves as the bat’s commuting corridor
The bats seem to use the riparian zone along the south edge of the river as a commuting corridor as they leave to forage.  Their hugging of the trees could partly be due to the bend in the river just past the Statesman property, but it could also be that there is some other benefit to hugging that tree line.  These trees have grown taller over the 34 years the bats have been roosting at the bridge and many people remember the views were better when the trees were smaller and wish they could be removed or selectively pruned to enhance the view of the bats.  However, with the increased development, the trees may become more important to block the lights from the buildings and preserve to dark commuting corridor used by the bats to come and go from the city, so as not to become disoriented by the city lights.  Again Dark Sky initiatives as pertains to light fixtures used to illuminate the new parkland could be critical.

3- Require bat-compatible building standards in the SCW to minimize bat human conflict
Firms choosing to develop in the flight path of 1.5 million bats should be required to develop plans that do not allow entry of bats into the voids between the exterior envelope and the interior living or working space of the buildings.  This increases the possibility of human/bat conflict and often leads to expensive bat exclusions.  Such exclusions thus become a Life-Cycle Cost of the building which is being handed down to the future owners and operators of the buildings and lead to headline of “bat infestations” when in reality it is a combination of lack of proper planning details and poor execution by the builders.  Developers should be required to pay for these Life-Cycle Costs up front by paying for drawing bat-proof building details and paying the contractors enough to properly carry out the design intent. This has not been the case in many of the latest high-rises along the flight path of the bats and needs to be required in the SCW district.

4- Make Austin Bat Refuge a stakeholder in any development application and approval process
This is the best strategy to mitigate the effects of the SCW development on Austin’s iconic bat bridge.

5- Incorporate an Austin Bat Refuge Education Center in the park
The original Bat Conservation Center was established in 1993 , by Merlin Tuttle, then-governer Ann Richards, and the Austin American-Statesman to shed light on the bat’s contribution to a healthy environment in the city of Austin.  The need still exists, all these years later, for an enclosed, secured, storage facility for specimens, brochures, posters, etc., with an overhang and apron with doors that open to deploy tables and literature as volunteers and visitors arrive for the emergence.  A video screen with thermal or night vision capabilities for bats emerging after dark would greatly enhance visitor’s experience during summer months of late emergences.

6- Park maintenance that is sensitive to the bat’s flight path
Flexibility is needed to trim tall shrubby vegetation close to the bridge that could impede emergences and allow input on selective tree clearing during development.

7- Extend the downtown panhandling ban to the SCW District
Any large, regular crowd of people attracts attention from opportunists who harass a captive audience into giving them donations.  Extending the panhandling ban would help eliminate the pervasive fear-based soliciting from the bridge area.

8- Limit facility lease agreements in the immediate vicinity of the bridge to quiet daytime events
Leasing of the Statesman lot for events with multiple loud bands (such as Bat Fest!) has a negative effect on the bats.  Emergences are down for many days after such events.  Many events use the viewing area for portable toilets, and rains during events have turned the viewing area into a nasty mudhole.

9- Limit the increasing violence of Fourth of July fireworks at Auditorium Shores – No Howitzers!
Every year the fireworks display at Auditorium Shores get bigger and louder.  Nowadays, firework events include military-style Howitzers whose exploding shells cause bat emergences to be almost non-existent for many days after such events.

Archive

Early Spring 2019

Our radar study was put on hold from Dec 22, 2018 to Jan 28, 2019 as the government shutdown took the weather radar viewer offline.
We lament not being able to monitor the Congress bats that were over-wintering.
Early Feb showed bats in big numbers at Fern and Stuart caves in West Texas; they appeared to be staging for early migration eastward.
They appeared to be moving east toward Frio before the subsequent cold snaps held them up.
Without continuity of observation we don’t know if they were there all winter or if they were early migrants.

An increase in numbers to ~230k occurred at Congress 09 March 2019.
Could be migrants pulsing through or some of our resident bats returning.
Intakes surged at the same time as we got 6 bats brought to our facility that weekend.

 

Fall 2018

Congress migration started 07 Nov 2018
Surges of migrants moved through periodically through November
Last big surge – 23 Nov – 471 k in the bridge
Warm, calmer weather brought out only 45k 29Nov and 22k 17Dec – 25k 20Dec
20 Nov – 360k in the bridge
15 Nov – Warmer southern breeze brings 230k bats out from Congress
01Dec – First calm evening in weeks brings surge from Congress – 147k
02Dec – another 197k flies S with N wind at 9 mph – Dittmar also strong
Return of radar after government shutdown shows 100k at Congress 28Jan2019