An artist’s rendering of what the South Central Waterfront development may look like. (Source)

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 was originally envisioned to be an office tower. It seems to have been changed to residential use, with accompanying light at night and viewing balconies (with potted plants in which bats frequently hide). Office buildings would be lighted less at night, and could have reduced lighting by using lighting controls such as timers or electronically tintable glass in order to prevent increases in ambient light at night so close to the bridge.

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. 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 a dark commuting corridor used by the bats to exit the city, so as not to become disoriented by the city lights. Dark Sky initiatives pertaining to light fixtures used to illuminate the new parkland could be critical

Flexibility is needed to trim tall shrubby vegetation close to the bridge that could impede emergences, and to allow input on selective tree clearing during development.

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 leads to headlines of “bat infestations”. 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-rise buildings along the flight path of the bats, and needs to be required in the South Central Waterfront district.

The proposed residential towers have been placed as close as they could possibly be to the bridge and will loom over it, with unknown effects on the bats. The intrusion into the psychic space of visitors to the bridge could degrade the bat viewing experience.

The increased levels of activity and noise during demolition, excavation, and construction will increase stressors around the bridge. Will the bats leave if it becomes too much? Would they return?

Consider the effect on the micro-climate of this bat maternity colony. Tall buildings near the bridge could partially shade the bridge during the winter and into the spring return. And the thermal mass created by all these new buildings could warm the area around the bridge, reducing the cooling airflow from the river and causing the bats to move out of the crevices onto the support structure.

These tall buildings may create wind tunnels, amplifying the prevailing southeast breeze, which could affect the bats at flight time.

Underground parking garages have the potential to become the Congress Avenue Bat Cave. Don’t blame bats if they move into what could appear to be just another Central Texas sinkhole. They dive from high altitudes to return to the bridge and could just as easily dive into the garage opening. We suggest air curtains to discourage them from doing so, but that may not be enough.

Developers reached out to us in September 2020 for the first time, and again in February 2021 – both times just hours before meeting with the Planning Commission – quite late in the game to shape a strategy to mitigate the effects of the 305 S. Congress project on Austin’s iconic bat bridge.

The original Bat Conservation Center was established in 1993 by Merlin Tuttle/BCI, then-governor Ann Richards, and the Austin American-Statesman to shed light on the bats’ contribution to a healthy environment in the city of Austin.  The need still exists, all these years later, for a dedicated education area in which to deploy tables for education materials as visitors arrive for the emergence.

A video screen with thermal or night vision capabilities for bats emerging after dark would greatly enhance visitors’ experience during summer months of late emergences.

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.

Leasing of the Statesman lot for events with multiple loud bands appears to have a negative effect on the bats, as 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 mudhole.

Every year the fireworks display at Auditorium Shores get bigger and louder. Nowadays, firework events include military-style Howitzers with exploding shells that cause bat emergences to be much reduced for some days after such events.

Can you help us with our vision to protect the bats?