Beneficial Bats

Mexican Free-Tailed bats

For millions of years, bats have long played essential roles in nature’s system of checks and balances.  Once extremely abundant, they dominated the night skies.  In more in recent times, however, their declining numbers reflect the ongoing compromise of the overall health and stability of our environment.

Bats are mammals, but such unique ones that scientists have put them in their own group, the Chiroptera, or “hand-wings.”    Occupying a large variety of habitats ranging from desert communities through pinyon-juniper woodland and pine-oak forests, there are 26 species of bats known to occur in Texas, but none is more commonly seen than the Mexican Free-Tailed bat.  These bats migrate each spring from Central Mexico to the same areas in the southwestern US, with the densest   concentrations occurring in Texas.  In fact, it is estimated that 100 million come to Central Texas each year to raise their young.   At approximately 1.5 million individuals alone, the Mexican Free-Tailed bat colony living under the Congress Avenue Bridge is the largest urban bat colony in the world!

Ranging from dark brown to grey, Mexican Free-Tailed bats are not much to look at, and some have described them as looking like “little gnomes with an overbite.”  They get their name from their tail, which protrudes freely beyond the wing membrane.  But don’t let their plain appearance fool you – these are the “speedsters of the bat world,” and they have been clocked flying at 60 mph using tail winds, and flying higher than any other bat at altitudes over 10,000 feet.  Mexican Free-Tailed bats are mostly migratory, with their arrival beginning in late February and their departure beginning in late October, triggered by the passage of strong cold fronts from the north.  Not all bats leave, however, and for unknown reasons several thousand of them stay behind each winter.  

Comprised mostly of females, the Austin bat colony sees an explosion of births in early June, when each female gives birth to a single baby bat, or pup.  At birth they already weigh one-third of their mother’s body weight, and are nursed by their mother who locates them among the thousands by each pup’s distinctive voice and scent.  In 5 weeks time the pup learns to fly and begins hunting insects on its own.  Aside from being fun to watch, bats make our world a better place to live.  They are gentle and incredibly sophisticated animals, and on each nightly flight out from under the bridge, they consume between 1,000 and 2,000 tons of insects (including agricultural pests)!  

Unfortunately, in spite of the popularity of the Austin bat colony, bats remain to be the world’s most endangered and least appreciated animals.  While bats suffer from environmental pollution and habitat loss like other wildlife, persecution from humans remains a primary cause for their decline.   Their colonies represent the most dense aggregations of mammals present in a limited number of locations, and combined with a low reproductive rate, recovery from the destruction of a large colony would be very slow.  As such, it is important to preserve those colonies that still thrive, and with the help of organizations like Bat Conservation International and The Nature Conservancy, along with private landowners, this unique resource and their habitat can be protected. 

Each summer night, when you join the hundreds of people gathered to watch the Mexican Free-Tailed bats emerge from their concrete roost in downtown Austin, you are witnessing one of nature’s most rare & awesome spectacles!

Morel of the Story

Mycology, or the study of fungi, used to be considered a branch of botany rather than biology, until it was recognized that fungi are most closely related to animals than to plants.  Mushrooms are the fruiting bodies of certain fungi, and while fewer than one thousand species have been identified in the state of Texas, it is estimated that as many as eight to ten thousand species remain to be identified!  Often associated with molds, mildews, and yeasts, several mushroom species are edible, and the most avidly hunted of all wild mushrooms is the Common Morel (Morchella esculenta).

The cap of the Common Morel is sponge-like, yellowish gray to tan in color, oval to mildly elongated, and has a mottled, pitted surface.  Its stalk is white, hollow, and has a slightly rubbery texture.  This species is most commonly found in our state growing in the limestone soils of Central Texas, but it has also been found in the acidic soils of East Texas and in parts of the Big Bend country.  It can be seen singly or in small groups on the ground under oaks and junipers, often along creek beds.  Its species name, esculenta, means ‘good to eat’, and morels regularly appear on the menus of some the best restaurants. 

Although a process to grow these mushrooms under controlled conditions was reported years ago, attempts to commercially cultivate them have been far from successful.  Laboratory studies have shown that common morels hold several medicinal properties, including immune system regulation, anti-tumor effects, fatigue resistance, and anti-viral properties.  This species has long been used in traditional Chinese medicine to treat indigestion and shortness of breath, and is even listed in the National Register of Medicinal Plants in the country of Nepal.  

Several similar species of morels are recognized in Texas, but the Common Morel is known by various colorful names, including yellow morel, sponge morel, Molly Moocher, haystack, and dryland fish.  Members of this species can vary in size, color, as well as the shape of the cap.  When cut down the center, the ‘true morels’ reveal a hollow stalk, unlike a ‘false morel’ that looks similar but the interior of its thick, white stalk is deeply furrowed or folded and not at all hollow.  Care must be taken to properly distinguish between the two, as the False Morel (Gyromitra caroliniana) is toxic to humans.

Mushrooms can be very photogenic and make for yet another reason for the whole family to walk new or familiar trails and see what earthy treasures can be found.  While morels normally occur in the spring, they can appear after any unusual period of cool, rainy weather. And that’s the morel of the story!