On a recent early morning in Brackenridge Park, just south of Joske’s Pavilion, hundreds of egrets and other migrant birds squawked from the tops of a few dozen trees, their droppings crusted like white paint on the ground below. The air reeked of bird feces.

In the river next to the rookery, a man wearing hip-high waders filled a small bag with water as three dead cattle egrets floated by, pin feathers marking two as chicks.

Bacteria levels in this part of the river are higher than in any other place in the San Antonio River, according to the San Antonio River Authority.

Chris Vaughn, the man in the waders, gestured toward the birds. “When you have overcrowding like this, it’s just ripe conditions for disease and an unhealthy population,” he said.

An aquatic biologist who works for the river authority as a watershed monitoring supervisor, Vaughn said dead birds impact bacteria levels as well as feces from the rookery.

Established in 1937, the river authority performs water quality monitoring, biological and habitat assessments throughout the San Antonio River Basin. Its jurisdiction covers 3,658 square miles — all of Bexar, Wilson, Karnes and Goliad Counties. As a part of this monitoring, the authority takes regular water samples at about 100 sites across the basin roughly every two months.

Three of its water testing sites are located within Brackenridge Park, one next to the birds’ nesting area, now located just south of the pedestrian bridge and historic Lambert Beach pump house.

The area has drawn attention from local environmental activists over the past several months due to plans outlined for the Brackenridge Park 2017 bond project, which calls for removing dozens of trees around historic structures.

While none of the trees slated for removal are in the area taken over by the nesting birds, early city drafts of the project noted that one benefit of nearby tree removal would be disrupting the birds’ habitat.

That revelation focused many activists not just on saving the trees, but also on protecting the birds and their nests.

The city claims the dense congregation of birds are a public health nuisance to park visitors. It has at times closed the nearby playground and restricted access to restrooms because of the bird droppings.

According to emails released to the San Antonio Report in response to an open records request, the city makes its claims in part based on water quality data from the river authority.

Water quality from this testing site has been poor for the last several years, said Shaun Donovan, the river authority’s manager of environmental sciences, due to several factors, including an increase in bird feces since the bird population nearby has increased.

“The [measurement] for bacteria here is higher than any other place in San Antonio,” Donovan said, including of E.coli, which is considered a fecal indicator for fresh water.

E.coli levels in 2021 averaged 3 to 4 times higher than recreational standards, according to river authority data. Bacteria levels go down when aquifer spring flows are higher, such as in 2018, Donavan said, but even then, E.coli levels are higher at this spot in the park than most other places on the river.

Since 2014, the collective samples taken from all testing sites across Bexar County show that on average, about 15% of the river’s bacteria comes from avian wildlife, according to river authority data.

“There are a lot of other sources of potential pollution in here,” Donavan said. “So while the rookery is a component of that, there are other considerations, other issues.”

San Antonio River water is collected in a bag before it is tested for bacteria such as E.coli.

High levels of bacteria can be unhealthy for visitors and for the aquatic species living in the river, Donovan said — and it’s not great for the birds either.

Migratory birds such as the cattle egrets nesting in the park will crowd together somewhat naturally, he said, but overcrowding such as the case in Brackenridge Park leads to diseases spreading quickly among the birds and hurting their population.

Birds also tend to be healthier when they don’t interact with humans, who feed them bread and other nutrient-free foods, Donovan said, displacing their natural, healthier diets.

But the city’s efforts to scare off the birds by clapping blocks and shooting off fireworks is simply cruel, said Alesia Garlock, a birder and “citizen scientist” who has been fighting the city’s bird removal efforts since before the Brackenridge Park bond project tree removal came to light.

The city had hoped to disturb the birds enough that they would roost and reproduce somewhere else ahead of nesting season so the tree removal could commence early this year. But fierce opposition to the tree removal delayed those efforts, and this year’s nesting season is well underway.

Bird feces cover a sign intended to make park visitors aware of nesting egrets and herons at Brackenridge Park on Thursday.
Bird feces cover a sign intended to make park visitors aware of nesting egrets and herons at Brackenridge Park in May. Credit: Nick Wagner / San Antonio Report

Garlock agreed it’s unhealthy for the birds to live in such tight quarters, but said it is the city’s fault the birds have had to congregate in such a small space. If the birds were allowed to spread out more, their population and feces wouldn’t be as concentrated, she said.

She added that the birds are already refugees, having relocated to the park after they were chased away from their former rookery near Kelly Field.

Donovan said he understands how stressful and tough on the birds it can be to move them from their nesting site in the park, but he thinks it’s the right thing to do.

“It would certainly make the water quality better here,” he said.

Donavan said he believes that in the long term, the birds will fare better somewhere where they can spread out more and eat healthier, which in turn will be healthier for the river and the humans who visit the park.

Beyond the loud noises, however, it’s unclear whether or how the city may try to move the birds after this nesting season.

In the past, efforts to create artificial nesting sites at Mitchell Lake on the city’s South Side didn’t work. The city has expressed a willingness to try such a project again, perhaps at Calaveras and Braunig lakes, as a former Audobon Society president has suggested.

“It’s not just, ‘We all want the birds gone because we want to go down the [playground] slide,’ it’s that we want the birds to be healthy, we want the river to be healthy, we want people to be healthy,” Donovan said.

Lindsey Carnett covers the environment, science and utilities for the San Antonio Report. A native San Antonian, she graduated from Texas A&M University in 2016 with a degree in telecommunication media...