Three eggs found in a nest at Elmendorf Lake have halted plans by the city and Joint Base San Antonio to remove cattle egrets from the West Side park, deemed a risk factor for aircraft using nearby military runways.

Federal law prevents the harassment and dispersal of breeding birds, so the discovery will buy time for opponents of the plan to suggest alternatives.

“Any effort to mitigate the overpopulation of birds will have to wait until the nestlings have hatched and matured,” District 5 City Councilwoman Shirley Gonzales said in a statement.

Gonzales said the eggs were that of a cattle egret. Bird watchers and Texas Parks and Wildlife officials said the cattle agrets haven’t yet arrived on their annual migration, and great egrets are the ones nesting there now.

No matter. The presence of any nesting bird means the city can’t use lasers, pyrotechnics, habitat modification and other tactics to encourage the many cattle egrets that roost on what’s commonly called “Bird Island” to move elsewhere.

The rookery has between 800 and 1,200 cattle egrets during breeding season that could endanger pilots and aircraft because they cross runways at JBSA-Lackland and Kelly Field at Port San Antonio on their way to forage at the Covel Gardens landfill and nearby fields, officials have said.

“The urgency remains,” and the mitigation plans will resume “when we’re authorized by law,” said Juan Ayala, the city’s director of military and veteran affairs.

On ExpressNews.com: Residents push back against city plan to move birds

Jessica Alderson, an urban biologist with Texas Parks and Wildlife, said the great egrets at the island now are typically the first to arrive, while the cattle egrets are usually “the last to come in and the last to leave.”

“They’re usually going to be active at the rookery site with fledglings until October,” she said, and continued monitoring will be needed because other birds may be there all year.

Newer interpretations of the Migratory Bird Treaty Act could allow for some habitat modification, such as removing tree limbs from the island without touching an existing nest, Alderson said. The city could try to get a special permit to pursue the removal but isn’t considering that option “as far as I know,” she said.

Thirty-five wildlife strikes were reported by C-5 operations at the 433rd Airlift Wing at JBSA-Lackland in 2018, a number that has risen each of the past three years, according to Air Force data.

At Kelly Field, there were 61 bird strikes in 2017 and 63 in 2018, but only a small number — eight strikes since 2010 — were known to involve cattle egrets, Aviation Safety Program Manager Bryan Wilmunen has said. About 5 percent of bird strikes result in damage, he said.

Residents near the lake said they didn’t learn of the dispersal project until after it was developed and announced in the days before it was to start. The city said it mailed notices about two community meetings this month to those living within a mile of the park and contacted 12 community organizations by phone and email. Ayala said he believes the city has been “as transparent as we possibly can,” by hosting the meetings and answering questions.

Robert Ramirez, co-chair of the Westside Creeks Restoration Oversight Committee, said the group, which works under the San Antonio River Authority, was “deprived of any oversight ability.”

“In no way do I want to minimize the threat to any human life, aircraft and air personnel,” Ramirez after the first meeting. “I don’t hear where other, less onerous, processes were vetted.”

Bexar Audubon Society President Anne Parrish said the delay provides an opportunity to find a balance between protecting the birds and their habitat and ensuring public safety. Given the large number of birds passing through San Antonio on the Central Flyway Migration Corridor, “it’s a matter of really finding some long term solutions,” she said.

JBSA started informal conversations with the city’s Parks and Recreation Department about an increased risk of bird strikes in early 2018, and biologists from the U.S. Department of Agriculture Wildlife Services and the state wildlife agency have been discussing it for more than a year. After unsuccessful efforts to adjust flight patterns, the military returned in December with a more urgent request.

The city will consider any timely suggestion or recommendation on how to address the problem, Ayala said. Gonzales, who previously said the situation “threatens the mission of Joint Base San Antonio and the activity at Lackland,” said in her statement that the delay is “an opportunity to continue to gather input and study alternatives.”

The city is “developing a public input opportunity on saspeakup.com and will notify residents upon its launch,” she said.

LTeitz@express-news.net