Experiencing Texas Bats

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By Renee Anna Cornue
4/22/19

As MTBC’s Photo Collection Administrator, much of my responsibility lies behind a computer screen. I’d seen thousands (about 120,000 if we’re being real) of photographs from Merlin’s most-active field work days, preparing me for what to expect as much as photographs can. I’d seen mist nets, harp traps, banded bats, guano piles, and evidence of the bats’ incredible diversity.

Though fortunate to see Austin’s bats in a variety of ways, I’d never worked with bats first-hand. On this trip, I was most excited to step away from the desk and learn how bats are studied in the field, especially surrounded by knowledgeable and talented peers.

As with MTBC’s past adventures, our trip was a hands-on working trip with invaluable time and expertise contributed by leading colleagues from varied specialties. We were in the company of expert bat researchers, photographers, videographers, rehabilitators, consultants and passionate citizen scientists as we searched for some of the least known bats in the U.S.

Merlin and local bat expert, Loren Ammerman, discussing first night’s objectives.

Our Big Bend area expert, Loren Ammerman, senior author of the book, Bats of Texas, has been surveying bats in Big Bend National Park for more than 23 years. Her guidance contributed greatly to our success. Some of her favorite locations took hours to reach over unmaintained backroads.

One evening, we had to carry our equipment nearly three-quarters of a mile up a steep mountainside in a 30-mile-per-hour wind while temperatures dropped into the 40’s. We could count on Loren for a lot, but controlling the weather isn’t her forte!

Crew wrapped in down jackets and space blankets while waiting for bats to be captured.

Amazingly, no one complained, and though we only caught two bats that night, I would argue this was one of the most enjoyable evenings. Despite the cold wind keeping the bats away, the site and bumpy drive were quite special– something like I’d never before seen in Big Bend. We were in good spirits and around 2 AM, wrapped the evening up with camp-stove hotdogs (thanks for teaching me how to make hotdogs, Jeff Johnson). I never even heard complaints about our 3 AM return from the field.

Crew hiking to the long-abandoned Mariscal Mine, now a protected home for bats, thanks in part to Merlin’s long-ago efforts.
Daniel Hargreaves (left) and Daniel Whitby setting a bat trap in front of one of the Mariscal Mine’s several protected entrances.

Unexpected finds

One of our goals was to capture a spotted bat (Euderma maculatum). Only three had been caught in the Big Bend area in the past 20+ years. Spotted bats are arguably North America’s most spectacular but least-seen mammals. Loren hadn’t caught one in over five years despite numerous attempts. We can only speculate on why these bats are so hard to catch, but two possibilities are their scarcity and tendency not to fly low enough to encounter nets.

Setting mist nets over pools in the Terlingua Creek.
Daniel Hargreaves hammering stake in ground in order to anchor a 20-foot-tall bat net pole. Sally-Ann Hurry stretches net to measure location for pole.



Janet Tyburec holds first of three nets to be hoisted up the pole while Joanna (middle) and Jen Shallman prepare for the net’s attachment. This is often referred to as a triple high rig.
Joanna Langdale secures guy-lines to hold bat net pole in place.

We also hoped to see the largest bat of the U.S. the western mastiff (Eumops perotis), well known to be an especially high flyer. In Merlin’s experience they only come low enough to be caught in a net set over water on exceptionally hot evenings.

Thanks to Janet Tyburec’s bat-detector expertise, we were able to repeatedly identify spotted bats flying over-head at multiple locations and mastiffs at one, but unfortunately, we were unable to actually capture either, even when we attempted to attract spotted bats with sophisticated ultrasonic lures.

Roger Jones (right) holds newly captured bat while Mindy Vescovo (center) and Bonnie Miles measure and record it prior to release.
One of several hoary bats we caught on the trip.

The first and warmest night was our best, resulting in 13 species captured, including one of America’s most fascinating mammals, the ghost-faced bat (Mormoops megalophylla).  This incredibly strange bat has its eyes literally located in its ears.

Overall, despite the cold front, we captured 227 bats in just five nights, including beautiful hoary bats (Lasiurus cinereus) migrating north, some likely headed for Canada. We also caught the U.S.’s smallest (and exceptionally cute) canyon bats (Parastrellus hesperus), the rarely seen pocketed free-tailed bats (Nyctinomops femorosaccus), and the first two western yellow bats found in the Big Bend National Park since 1996, when the species was first recorded from Texas.

 

In addition to the 13 species we netted or trapped, Janet recorded the echolocation calls of four more, the spotted, mastiff, silver-haired (Lasionycteris noctivagans), and big free-tailed bats (Nyctinomops macrotis).  In just five nights, our hard working team captured or recorded the calls of 17 species out of 24 likely to have been present during our visit.

Robin Eastham (left) helps Bonnie Miles remove a Yuma myotis (Myotis yumanensis) from a mist net.
Recorded echolocation calls of a spotted bat.
Echolocation recording of a fringed myotis (Myotis thysanodes).
Echolocation calls of a ghost-faced bat (Mormoops megalophylla). The three species we show have strikingly distinctive calls that make them easily identifiable. However, some species, either due to use of faint calls or a wide range of call types, cannot be reliably identified by calls alone. We caught two species whose calls were not detected and recorded four others who were not captured.

Both canyon bats and pallid bats were unusually elusive on this trip. We were only able to catch four and five, respectively. Merlin had caught more than 100 pallid bats in one night at a Big Bend drinking site some 30 years ago, so their scarcity this time was a surprise. One of the pallid bats we did catch was unexpectedly covered in pollen at a time of year when there were no known bat-pollinated flowers blooming, raising the question of what it had found that we are unaware of.


In good company

Pallid bats are generally unhappy about posing for photos, though this one was more cooperative than most.

Like humans, bats have unique personalities. One pallid bat remained calm and almost seemed to be smiling for photos, whereas the next one promptly closed its eyes and bared its teeth. Brazilian free-tailed bats (Tadarida brasiliensis) are normally exceptionally calm and gentle. However, on this trip the two sexes behaved very differently. The males were calm as usual. But the females threw “tantrums” when netted. Merlin was quite surprised, but some in our group suggested, “They must be pregnant.”

John Chenger helping set a “triple-high” netting rig.

John Chenger, founder of Bat Conservation and Management, was an invaluable source of technological and videographic expertise. Over the past year, he has been partnering with MTBC to shoot educational videos. Much of the content he shot on this trip will be incorporated into new programs.

In her more than 30 years studying American bats, Janet was thrilled to finally see her first ghost-faced bat as Jen looks on.

Janet Tyburec was originally trained by Merlin in bat conservation and research techniques and is now a leading expert on ultrasonic identification of bats. She has 30+ years of experience teaching bat conservation workshops and has now taught over 3,000 students invaluable research and field techniques. For the past 15 years, she’s teamed up with John Chenger to provide a wide variety of bat conservation and management training.
Tyburec had been waiting decades to capture and record her first ghost-faced bat (Mormoops megalophylla). Her long-awaited goal was met within just hours on our first night. We ended up catching five at three different sites.

A ghost-faced bat showing eyes located in its ears and strange skin flaps on its face.
Janet releasing her first ghost-faced bat while Teresa Nichta video tapes and Robin and Bonnie observe.
Merlin explains bats to visitors from a nearby campground.

Nearby campers get curious when more than a dozen people show up with 20-foot-long poles with nearly invisible nets strung between them, start raising microphones high above ground, and even set up what appear to be large harps. At two locations we provided considerable entertainment as we welcomed campers, and on one cold night even shared hot chocolate with them.                     
It was great to see how excited our guests were to experience bats up close. Their eyes really lit up in response to Merlin’s famous story-telling. We were always glad to share our work.

Bat team and campground visitors look on as Merlin prepares to release a seldom seen pocketed free-tailed bat (Nyctinomops femorosaccus). Because of its narrow wings and jet-like flight this bat needed a special toss with its wings held open to regain flight.

They also were fascinated to see the varied techniques by which bats are photographed, especially Merlin with his portrait set-up and Daniel Whitby, a United Kingdom bat ecologist, using an infrared beam triggering device to catch them in flight as they were released. John Chenger and Teresa Nichta shot video to be used in new MTBC programs and I  photographed everyone and everything, so that our participants could share their experiences.

Teresa and Sally-Ann help Merlin as he prepares to take bat portraits.
Merlin photographing a ghost-faced bat.


Roger (left to right), Jeff, John, and Sally-Ann observing Merlin’s bat portrait techniques.

A Yuma myotis.
A pocketed free-tailed bat.


 

 

Merlin and Daniel Hargreaves showing Mindy Vescovo the remains of a pallid bat’s’ meal. These bats often “night-roost” in porches where they drop inedible wings and legs of prey, in this case including the legs of a large spider and wings of a sphinx moth.
Kathy Estes assisting with breakfast preparations.
Jeff Johnson inspecting a tiny Yuma myotis.
Jen releasing a Brazilian free-tailed bat.
Crew hiking equipment in to Terlingua Creek netting site.

Though faced with challenging weather, little sleep, and jarring roads, several participants declared their experience “the trip of a lifetime.” Reaching and setting up research stations required hours of rugged driving and carrying a seemingly endless assortment of equipment, but
the scenery was unbeatable, and the team enthusiastic and full of fun.

Daniel Hargreaves carrying nearly 100 pounds of gear up to the Mariscal Mine.

Despite the challenges, Daniel Hargreaves, our U.K. bat-expert who played a key role in helping Teresa Nichta organize the trip, always had a smile to share, an encouraging word, and an offer to carry a larger load. We could expect a delicious breakfast each morning from Mindy Vescovo, Kathy Estes, and Jeff Johnson. Even through exhaustion, Roger Jones and Sally-Ann Hurry could be counted on for a laugh. The positive energy given from our participants was palpable. We could not have asked for a more appreciative and excited group of bat enthusiasts. I’d been to Big Bend National Park more times than I can count, but never quite like this.

Prior to the long drive to the Big Bend area of Texas we were treated to a seemingly endless bat emergence from the famous Bracken Cave near San Antonio.


At trip’s end we were treated to a bat watching cruise at Austin’s famous Congress Avenue Bridge. Though we did see some bats, that evening was marred by rain.

Myself as the official trip photographer, as usually seen.