Dr. Charles Campbell and San Antonio's Bats - Journal of San Antonio

by Frank W. Jennings

"The world’s largest known concentration of mammals"—the bats at Bracken Cave—lies on the outskirts of San Antonio, according to the National Geographic Society.

No wonder that in old books telling about San Antonio’s history you can find stories about bats being intimately involved with the city for more than a century.

A visitor to San Antonio in 1846 spoke of the "myriads" of bats that inhabited the abandoned Mission Concepcion.

The local seat of government in the mid-1800s was in a two-story building in Military Plaza called "the Bat Cave," because it housed so many.

During the Civil War, late in 1863, guano, the bat droppings found in bat caves, was used by the Confederacy as a source of saltpeter in a gun powder factory a few miles below San Antonio. The guano was brought in wagon loads from caves 30 to 60 miles distant. Burros, with rawhide boxes strapped on each side, were trained to go into the caves to be loaded with guano.

The world’s first successful experiments with attracting hundreds of thousands of bats to fight malaria-carrying mosquitoes were conducted in the early 1900s by a San Antonio doctor who invented tall towers designed as bat roosts.

Today, bats are still of more than fleeting interest to San Antonians. To avoid colliding with flights of bats, T-38 pilots training at Randolph Air Force Base take special precautions from April Fools’ Day until Halloween. They suspend their daytime flying at 30 minutes before official sunset, and don’t take off again until 30 minutes after sunrise.

If you were to drive northeast on Interstate 35 toward Austin—just outside Beltway 1604 on the edge of San Antonio—you might see Bat Cave Road heading north to old Nacogdoches Road and Bracken Cave.

Within 80 miles of San Antonio are three very large bat caves -- plus possibly the largest urban bat colony in the world. Some 750,000 bats live under the Congress Avenue Bridge in downtown Austin.

The largest colony of Mexican free-tail bats on Earth is in Bracken Cave, privately owned in Comal County. There are more than 20 million bats there—the largest known grouping of warm-blooded animals anywhere. The Frio Cave in Uvalde County and the Ney in Medina County are also among the world’s large bat caves.

As nightfall approaches—as long as two hours before sundown—what appear to be dark clouds of bats come swirling and billowing out of Bracken Cave, making a clockwise circle and flying off to the south.

Even from two miles away, great columns of the bats can be seen rising from the cave. They may ascend to altitudes above 10,000 feet, where tail winds can help them achieve speeds of more than 60 miles per hour en route to distant feeding grounds.

In one hour one bat can eat 100 or more night-flying insects. The bats at Bracken Cave consume an estimated half a million pounds of insects nightly.

According to Merlin D. Tuttle’s popular book, America’s Neighborhood Bats, "given the incredible numbers of insects eaten, including many pest species, free-tailed bats undoubtedly play a vital role in the checks and balances of nature."

Tuttle, who is founder and science director of Bat Conservation International, an educational and protective organization with headquarters in Austin, spends a great deal of time spreading the word that bats are not flying rodents, they’re very special animals. They’re closer to the monkey and ape family than to any other, but they’re different.

Bat Conservation International dispels old myths about these mysterious and sadly misunderstood night creatures, proving that they’re our friends, not our enemies.

Bats can see quite well and also have a kind of sonar. They have no interest in getting into people’s hair, as some folk believe; further bats are no more rabid than any other wild mammal. More people die from dog bites in one year than from bats in decades. Only 10 people in the U.S. and Canada are believed to have died from bat rabies in the past forty years. Yet, hundreds of thousands of bats live in buildings in cities where they’re close to people.

There are nearly a thousand kinds of bats: some, the world’s smallest mammals, the size of bumblebees, weigh less than a penny; some bats, called "flying foxes," have six-foot wingspreads. Some eat fruit; some, much like bees, eat nectar. Many important plants and trees owe their survival to the pollinating habits of bats.

Without bats we’d be without many fruits, nuts and spices, or even tequila and rope fiber, which come from the agave plant. We can thank bats for our bananas, dates, figs, avocados, mangoes and cloves.

They’re our planet’s most important predators of night-flying insects, they provide tons of valuable fertilizer, guano, in countries where it’s collected, and they’re extremely useful in medical research.
They’re exceptionally long-lived; some live longer than 30 years.

Young bats, usually one per female, are born and raised in June and July. Like a monkey, the mother nurses her young from a pair of pectoral breasts. Mother bats, returning to their caves, must find their own babies among millions of young bats packed 5,000 per square yard.

Summer bat roosts in South Texas bat caves are abandoned as the weather gets cool in the fall, and these animals fly south to Central Mexico to spend the winter.

No one would want to say that San Antonio is batty, but it never has been without an enormous bat population. At one time, the most important building in town, not counting any church, was "the Old Bat Cave." It became one of the most famous buildings in San Antonio’s history. The two-story building served as the city hall, courthouse and jail until after the Civil War.

This arena for San Antonio’s and Bexar County’s local government in the late 1800s was near the Governor’s Palace in Military Plaza. It was occupied by both the county and the municipality as courthouse and city hall. The jail was in an adjoining two-story building, surrounded by a wall. The upper floor of the main building was originally the district courtroom. The lower floor was used for the city court and city department. For a time, the county courtroom was also used on Sundays for Methodist church services.

Charles Herff wrote: "Thousands of bats made their homes between the roof and the whitewashed canvas ceiling of the courthouse. It was necessary, whenever court convened, to drive the bats out by using two long poles and a cross-piece of timber, which was bumped against the canvas ceiling."

According to Sam and Bess Woolford, authors of The San Antonio Story, the Methodists followed that same procedure on Sundays.

The Bat Cave was an important meeting place for San Antonians. In Courthouses of Bexar County, published by the Bexar County Historical Commission, Sylvia Ann Santos writes that "the building was also used by civic and religious groups. According to tradition, it was the site for the first gathering of Baptists in the community." The Vigilantes of the Civil War also met there, as did organizational meetings of the Belknap Rifles, a nationally competitive military drill team.

The main offices of the city were moved to another building from the Bat Cave in 1859, and the county offices, in 1868. Finally, the Bat Cave was torn down around 1889, when it was replaced by today’s City Hall.

And where did the bats go from the Bat Cave? Probably to other inviting shelters in the area. When the new city hall was completed in Military Plaza in 1892, the teeming and colorful marketplace of San Antonio was moved two blocks away to today’s El Mercado in Market Square.

Today, early on a summer’s evening, you can see darting flights of bats fluttering out from under the second floor parking lot at Market Square. Many large buildings throughout the city—such as the Moody Learning Center at San Antonio College—provide, not always hospitably, homes for bats.

But back in 1919, some San Antonians were remarkably fond of bats. The citizens of Alamo Heights, then a new community of fine homes north of the city, near the head of the river, raised funds through popular subscription for construction of "the Alamo Heights Bat Roost."

The high wooden tower, like a church cupola or steeple on tall stilts, seemed oddly out of place on the hillside in Olmos Basin. On the hill that sloped above it was the fort-like West Texas Military Academy, with its crenelated walls. The stilted tower below was "Doctor Campbell’s Bat Roost," and inside it were 100,000 mosquito and insect pest eradicators.

That year of 1919 was a big one for Dr. Charles A. R. Campbell. The benefits from his bat experiments, which he’d begun in 1902, had resulted in his first successful bat roost at Mitchell Lake south of the city in 1911, and his later successes were earning him international recognition.

His achievements were summarized in a House Concurrent Resolution by the Texas State Legislature recommending him for a Nobel Prize. The resolution was approved by the governor on February 18th, 1919. Doctor Campbell had "rendered the State of Texas and humanity valuable service in his original and conclusive experiments during the past seventeen years for the eradication of malaria by the cultivation of bats, the natural enemy of mosquitoes."

The resolution continued, "The world’s greatest Sanitarian, Gen. W. C. Gorgas [who pioneered mosquito control at the Panama Canal], the Board of Health of the State of Texas, the San Antonio Medical Society, and other sections have given this natural hygienic measure their unqualified endorsement.

"The Italian Government has given special recognition to his work and distinguished service, as well as other foreign countries.

"The colossal economic loss caused by malaria is sufficient to warrant State and Nation in giving this natural hygienic measure full encouragement."

The resolution endorsed Doctor Campbell "in his original and thoroughly scientific work," and commended him "as worthy of the greatest reward for the service of humanity, a Nobel Prize."

Doctor Campbell had worked for years on his bat attracting and pest-eradicating invention, trying to find the secret of building a device to concentrate bats in a selected location.

The bat roost he built in 1911 to combat malaria-carrying mosquitoes at Mitchell Lake, south of the city, seemed to face an almost hopeless challenge, at first. Water covered 900 acres from a few inches to 25-feet in depth. All the sewage from San Antonio flowed into it. The enormous clouds of mosquitoes there were the scourge of farmers and farm animals.

Malaria, according to Doctor Campbell, infected 89% of the people around the lake. In his book, Bats, Mosquitoes and Dollars, published in 1925, Campbell explained how his experiments were conducted.
In 1914 he examined these people and found not a single case of malaria. The bats had not only rid the area of mosquitoes, but his bat roost had produced each year some two tons of the valuable fertilizer, guano.

An article in the Scientific American by Doctor Campbell in 1915 brought widespread interest. A photograph of the spectacular bat roost appeared in The London Illustrated News, with a caption. After two 30-foot tall roosts were built in Italy according to Campbell’s plans, the idea spread rapidly through Europe. Tens of thousands of smaller versions of his roost were put in forests.

The bat houses never were used much in the United States until the early 1980s, when smaller versions of the roosts began being popularized, and building plans suggested, through programs of Bat Conservation International. Now, more and more people in the United States are putting small bat houses in their backyards and nearby parks.

Some people in San Antonio today remember Doctor Campbell’s bat roosts, not only the one near Texas Military Institute, but one in what is now Cassiano Park, near Apache creek and Zarzamora and Laredo streets. There also was a bat roost erected by the state of Texas at what was known then as Southwestern Insane Asylum in San Antonio.

Campbell was enthusiastically supported by other medical doctors and by the city fathers. On June 8, 1914, the City Council approved an ordinance signed by the mayor that anyone willfully killing bats in the city would be fined up to $200. In 1916, the city erected a "Municipal Bat- Roost."

On March 10, 1917, the governor of Texas signed into law a prohibition against killing or injuring "any winged quadruped known as the common bat." The perpetrator of such a misdemeanor could be fined as much as $15.

But the day of the large bat towers seems past. Today, there are only three left, two on private property in Texas and one on Sugar Loaf Key in Florida.

You can see one today near Comfort, Texas, 30 miles from San Antonio, at the country home of Marshall Steves. His grandfather, Albert Steves, a prominent San Antonio business and civic leader and former mayor, had erected the bat roost in 1918, using the Campbell plans. He described it as "hgestalt," meaning, "standing for health."

San Antonians have had a healthy relationship with bats throughout much of the city’s history. And as long as San Antonio remains the bat haven of the world, San Antonians can agree with Bat Conservation International in Austin that bats are not to be feared. They are not our enemies; they’re our friends, our allies, beneficial in destroying harmful insects, pollinating valuable plants and serving in medical research.


Bat Conservation International, Various pamphlets, P.O.Box 162603, Austin, Texas 78716-2603

Campbell, Chas. A. R, Bats, Mosquitoes and Dollars,. Boston; Stratford Co. Publishers, 1925.

Grove, Noel, “Quietly Conservating Nature,” National Geographic, Dec. 1988, page 822.

Lenz, Mary Domain, "The House in Bat Taste" Texas Monthly, May/June 1989.

Outdoor San Antonio and Vicinity, A Sierra Club Guide, 1986.

Santos, Sylvia Ann, Courthouses of Bexar County, 1731-1978, Bexar County Historical Commission, 1979.

Tuttle, Merlin D., America’s Neighborhood Bats, Austin, University of Texas Press, 1988.

Woolford, Sam and Bess, The San Antonio Story, Austin, The Steck Co., 1950.