The Flat-headed Bat: a species back from the dead?

The Flat-headed Bat (Myotis planiceps) is special in many ways. With forearms no longer than one inch, it is one of the tiniest bats in the world, found exclusively in the Chihuahuan Desert of northeast Mexico in an area of less than 193 square miles (500 square kilometers), which is not only the smallest distribution of any continental bat but of any mammal. As its name suggests, the Flat-headed Bat has an incredibly flat skull and no forehead at all, distinguishing it from other Myotis bats, such as the closely related Long-legged Myotis (M. Volans), which is widespread in the western United States.

The Flat-headed Bat is also a species that effectively came back from the ‘dead.’ The IUCN declared it Extinct in 1996, after there had not been any scientific documentation of the species for 21 years. Only three individuals had been collected since it was first documented in 1953.

“There was no hope that anybody could find an extinct species,” says the ‘Bat Man of Mexico,’ Rodrigo Medellín, senior professor of ecology at the National Autonomous University of Mexico (UNAM), who has been central in the conservation and study of some of Mexico’s 137 different bat species.

But as it turned out, the Flat-headed Bat didn’t stay classified as Extinct for long. In 2004, Medellín’s team set out to northeast Mexico to the localities of Los Pinos, Las Armenias and Lontananza, based on the areas where the individuals were first found, and discovered eight of the bats, confirming that the species was still very much alive and offering new hope that it could be saved.

“Once we found it in 2004, it was obvious we needed to launch a major effort to understand the conservation needs and the threats that are affecting them, and of course the actual state of the species,” says Medellín.

His team returned to the same site several more times in the years following, each time managing to find more of the bats, albeit in low numbers.

It was last year, however, that they had their greatest success yet. In July 2021, a team led by Daniel Ramos, one of Medellín’s students at UNAM, decided to venture further out to the Sierra de Zapalinamé Nature Reserve to look for the bats, where the group set up mist nets in water pools in the hope of catching, counting and releasing any individuals. After that, it was simply a matter of waiting–though their efforts weren’t fruitful at first.

“After several captures of other bat species but without success [for M. planiceps], we were going to close the mist net,” says Ramos. “Then, almost at the end of the night, we captured [and released] the first Myotis planiceps bat, and on the first night of sampling we were able to capture five bats. Considering that this species is relatively rare and that few people have been able to find it, I felt super excited since we were evaluating a new area for us, a new area even for the members of Rodrigo’s lab. I also remember the great joy of notifying Rodrigo of these captures, and being able to show him the photos and videos of M. planiceps.”

After their first night, the team began finding the bats regularly and in larger numbers than previous field trips. This was a victory not only to further corroborate what scientists know about the species, but also to include Sierra de Zapalinamé as a new place of record for these bats and uncover new information that could aid in their protection. From July to September 2021, Ramos and his colleagues managed to capture 28 individuals and locate 28 summer roosts, thanks to the use of radio transmitters that were fitted onto 23 of the bats.

Roosts are indispensable to bats. Since they only spend a few hours out of their roosts at night to hunt, bats depend on these shelters for everything from digesting their food to mating and rearing their young to hiding from predators. Thanks to the efforts of Medellín’s team, we now know that the Flat-headed Bat roosts among the dry leaves of yucca trees in the summer, but only the taller trees of four or more meters.

However, many questions still remain, such as the bat’s diet (we know it eats insects but not what kind), and where and how they hibernate in winter, which is one of the priorities for forming a conservation plan for the species, says Ramos.

“Previous studies suggested that these bats could move to their winter roosts in late July due to a lack of captures after that date,” he explains. “However, in the 2021 study it was possible to locate roosts of active bats in early September, which provides new information about their ecology prior to winter. Thanks to this first experience, now we want to search for bats during September, October, and even November.”

Currently, Medellín is in the process of launching a finalized recovery plan for the Flat-headed Bat, which is listed as Endangered by both the IUCN and the Mexican Federal List of Endangered Species. He is joining forces with those who own the area, drafting an agreement to maintain the landscape so as to minimize risks to the bats–the main threats being fires, deforestation (particularly of yucca trees, which act as their main roosts. and pine trees that make up much of the forests) and the infringement of human development from nearby cities.

“This is an essential species for Mexican biodiversity because it is such a unique species: tiny bat, tiny, endemic distribution, tiny population, flat head, revived from the dead. Clearly a very special species. It is our responsibility as Mexicans to protect all biodiversity, all the more such special, charismatic species,” says Medellín. “We basically know nothing about this species still, and the morphology is so strikingly unique and different from any of its relatives that nobody would doubt that their natural history and their conservation are going to be unique. There are a lot of lessons to be learned from the Flat-headed Bat.”

Those lessons could be applied to other species to help with their rediscovery, such as the New Zealand Greater Short-tailed Bat–one of Re:wild’s most wanted lost species. In the meantime, we can look to the Flat-headed Bat as a shining example of a species that both nature and conservationists are not giving up on yet.