The impact of 151 continuous hours of freezing temperatures continues to take its toll on area wildlife this week as biologists, ranchers, and conservationists assess the damage of the historic Texas freeze known as Storm Uri.

The death toll is pervasive and well-documented.

On Feb. 22, Texas Parks and Wildlife Department launched a community science initiative called Winter Storm Uri Wildlife Deaths via the iNaturalist app.

“As of this morning we have observations from 617 people with 2,539 observations of 239 species,” said Craig Hensley, Texas Nature Trackers biologist for Texas Parks and Wildlife. “Sadly, a good response – sad that there was such loss of life across the wildlife spectrum.”

The storm appears to have hit the local bat population especially hard, according to Fran Hutchins, director of Bat Conservation International‘s Bracken Cave. While the total death count is still being tallied, he said losses likely will tally more than 10,000 bats. Merlin Tuttle, founder of Bat Conservation International and Merlin Tuttle’s Bat Conservation, suggested losses could top 100,000 bats.

Several thousand dead bats have been found under San Antonio bridges. Local nonprofit Southern Wildlife Rehab rescued thousands of dehydrated, starving, near-frozen bats, housing them in tents at its San Antonio facility. The bats are valued for the free ecosystem services they provide. They pollinate crops and eat their body weight in insects each night.

Hutchins toured Bracken Cave on Saturday and said the bat population there was intact, with about 100,000 overwintering bats. “They’re pretty comfortable, with plenty of decomposing bat guano serving as insulation, keeping the cave warm. Caves don’t get below freezing in this area,” said Hutchins.

Because of our changing climate, some of the bat population has been remaining in Texas in recent years, rather than migrating to Mexico, Hutchins explained. Some bats stay in the cave, but others roost in bridges – which is advantageous in hot summers.

“Bridges act like an AC unit for bats, which is great for summer but deadly during a winter freeze,” said Carson Sartain, senior marketing and communications manager for the Nature Conservancy of Texas.

Hutchins called the situation “concerning” because bats are slow reproducers.

“They only have one pup a year. We’re talking thousands of bats that have died and some of those are females. You lose a female bat, you lose a baby bat. That’s a big deal,” he said.

A kayak tour of the San Antonio River’s South Channel last week included several sightings of bats hawking for insects, but also dead tilapia, carp, dove and suckermouth catfish, a South American catfish commonly sold as an aquarium pet. The fish has leopard-like black and white markings and typically grows to only a few inches long in captivity but, when released into the wild, can grow longer than a foot.

A dead suckermouth catfish floats in the San Antonio River after February’s historic freeze. Credit: Courtesy / Monika Maeckle

“We’ve seen a few hundred dead fish, but everything we’ve seen so far has been tilapia and plecostomus [suckermouth catfish],” said Shaun Donovan, manager of environmental sciences at the San Antonio River Authority.

In the Hill Country, exotic game ranchers reported hundreds of dead wildebeest, axis deer, blackbuck antelope, and other mammals imported for commercial use as breeding stock and for game hunts. Truckloads of dead axis deer, native to India and brought to Texas in 1932, circulated online and in news reports.

Charly Seale, president of the Kerrville-based Exotic Wildlife Association, told the Washington Post that Storm Uri cost the exotic game industry more than $2 million in dead animals and another half-million in infrastructure damage.

Jennie Singleton of the Singleton River Ranch said her family lost 14 blackbuck antelope and at least one oryx to the freeze at her family’s 480-acre ranch, which they lease out to hunters.

“I thought the fire ants might have died. But NO! Saw mounds along the trail when I was walking yesterday,” said Singleton, who lives in Grapevine but spends much of her time at the ranch in Menard.

Blackbuck antelope and an oryx fell to the freeze in Menard. Credit: Courtesy / Singleton River Ranch

Contrary to popular belief, Storm Uri likely will not set back the tick, flea, and fire ant population. “That’s an old wives’ tale,” said Molly Keck, Texas Agrilife Extension entomologist in San Antonio.

“The fireants are fine,” said Keck. “I’m still seeing plenty of them popping up after the rains in my yard.”

Fire ants are smart enough not to stay above ground when they’re uncomfortable, she said.  “If you were to kick a mound on one of those super cold single digit days, you wouldn’t see any activity and I bet you would also see steam because the soil was warmer than the air.”

Nor will ticks and fleas be much affected, said Keck, because soil temperatures didn’t get to freezing, especially a bit deeper and where most insects go.

“Insects also have substances in their blood (hemolymph) that act like antifreeze to prevent them from actually succumbing to freezing,” she said. They also tend to overwinter as the egg or pupa and are much safer from colder temps, she explained.

What’s usually more harmful to the insects is inconsistency of temperatures. “They get confused, come out of their overwintering state, want to mate, and then it freezes or dips low again, disrupting their lifecycle and mating patterns,” said Keck.

A temporary absence of some insects will deny food to bats, birds and other insectivores, though.

“Insectivorous birds, like flycatchers, will likely have problems finding food after the freeze,” the Nature Conservancy’s Sartain said.

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Monika Maeckle

San Antonio Report co-founder Monika Maeckle writes about pollinators, native plants, and the ecosystems that sustain them at the Texas Butterfly Ranch website. She is also the founder and director of...