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!

A Bird That Prefers to Run

Greater Roadrunner, Geococcyx californianus

Spend any amount of time in Texas or the southwestern United States and you’ll undoubtedly spot the Greater Roadrunner, a long-legged, ground-dwelling member of the cuckoo family.  It is regionally called ‘paisano’, meaning constant friend or compatriot.  This large chicken-like bird, with its long tail and shaggy crest, is fully capable of flying, but usually runs instead, at speeds up to 18 miles per hour.  True to its name, a group of these birds is known as a ‘marathon’ or a ‘race’ of roadrunners.   

From a behavioral point of view, the roadrunner is a fascinating subject.  This signature bird of the southwest slows its bodily functions at night, and conserves body heat by lowering its temperature and becoming lethargic.  In the early morning, it can warm itself up without expending a lot of energy.  Turning its back to the sun, it erects its feathers to expose an underlying patch of black skin between its wings that helps it quickly absorb more solar energy.  When running at top speed, it holds its head and tail flat and parallel to the ground.   

Roadrunner warming up in the sun by exposing dark skin

The roadrunner is an opportunistic forager, and while it can catch small birds at feeders and nest boxes, more often it eats a variety of fruits, seeds, as well as venomous prey items, including large insects, spiders, scorpions, and even rattlesnakes.  Surprisingly agile, two birds will frequently cooperate to kill a large snake, taking turns to distract it, pin its head with their heavy bill, and beat it against a rock or the ground.  When alarmed or curious, the roadrunner raises its crest and white-edged tail, and utters a series of coos or rapidly clatters its beak.

Living in dry, open habitats, the roadrunner has adapted by developing salt glands in front of its eyes to excrete excess salt from its blood.  While these glands are more common in ocean-going birds that drink seawater, the roadrunner is able to go without drinking water as long as it eats food with high moisture content, but will drink water if it is available.  When courting, many male roadrunners attract a female with cooing calls and then offer her food, usually in the form of a dead lizard.  If the female accepts, copulation occurs, during which the food is often exchanged.

Roadrunners in love

In a small tree, scrubby bush, or a stand of cactus, both parents build a shallow platform of thorny sticks, line it with leaves, grass, feathers, and occasionally shed snake skins.  Clutch size can vary from two to six eggs, depending on the food supply.  If all the eggs do not hatch at roughly the same time (called asynchronous hatching), and the food supply declines during the breeding season, the parents may eat the younger chicks or feed them to their older siblings.  In times of abundant food, roadrunners will double-brood, or raise a second family just as soon as the first is out of the nest.

Greater Roadrunner populations appear stable across their range, and are seen in central Texas year-round.  However, like most species, they tend to disappear when their habitat is fragmented by development.    

Dabblers and Divers

Wintertime is the perfect time to look for ducks in Central Texas.  Several species that breed far north of our state’s border return to Texas in the colder months to feed in our unfrozen freshwater lakes and rivers.  From the Old English ‘duce’, the word duck is a derivative of the verb meaning to duck or dive, or bend down low as if to get under something.  It best describes the way many ducks feed, by upending or diving under the water in search of a wide variety of food sources, such as small aquatic plants, grasses,  fish, insects, amphibians, worms and mollusks.  Most ducks fall into either the dabbler or diver category.  Dabblers feed on the surface of the water, and sometimes on land, while divers disappear completely beaneath the surface and forage deep underwater.  In general, divers are heavier than dabblers, which gives them the ability to submerge more easily, but they often pay the price by having more difficulty when taking off to fly. 

Northern Shoveler, Anas clypeata

The most distinctive dabbling duck is the Northern Shoveler (Anas clypeada).  True to its name, it possesses a two and a half inch long bill, which is spoon-shaped and has a comb-like structure called a pecten at the edge of its beak.  The pecten is used to filter food from the water and to aid in preening its feathers.  A medium-sized duck, the adult male (or drake) has an iridescent green head, rusty sides, and a white chest.  When flushed from her nest, the adult female (or hen) will often defecate on the eggs, presumably to deter predators from eating them.  This species of duck is monogamous, and stays together longer than any other known pairs of dabbling duck species.  

American Wigeon, Anas americana

Another common dabbler is the American wigeon (Anas americana), whose population is increasing throughout its range.  The male has a white crown, green face patch, large white patches in its wings, and a black rear end bordered by white.  At one time this duck was known as ‘baldpate’ due to the white crown resembling a man’s bald head.   Its feeding behavior is distinctive among the dabbling ducks, as its short bill allows it to be much more efficient at plucking vegetation from both the water and sometimes even agricultural fields.  The diet of this duck has been shown to include a much higher proportion of plant matter than any other dabbler species.

Lesser Scaup, Aythya affinis

Among the most abundant and widespread freshwater diving ducks is the Lesser scaup (Aythya affinis).  The male has a slight bump or peak on the back of the head, a bluish bill with a small black tip, grey sides (black on the ends with white in the middle), and a black head, chest, and rear end.   When grasped by a predator like a grey fox, an adult Lesser scaup may play dead, rendering itself immobile with its head extended, eyes open, and wings floded close to its body.  They are capable of diving underwater the day they are hatched, but are too buoyant to stay under for long, until maturity gives them the body composition and strength they need to stay underwater for longer periods of time.

Usually found on smaller, calmer bodies of water like ponds, Ring-necked ducks (Aythya collaris) are more readily identified by the bold white ring around their bill that the subtle purplish band around their necks for which they are named.  A medium-sized diving duck, they also have a small bump or peak on the back of their black heads, with the male having a black chest, back, and rear end, with grey sides and a white stripe up the shoulder.

Gadwall, Anas strepera, is another common duck of Central Texas

The next time you visit a lake, river, or pond this winter, venture out to the quiet corners to see if you can spot one of our best known dabblers or divers! 

The Cunning Coyote

Coyote, Canis latrans

Although the coyote has been (and continues to be) one of the most persecuted mammals in human history, this is largely due to the common misconceptions and myths that surround the species.  Add the fact that they are a highly intelligent animal with keen senses of hearing, sight, and smell, and you can easily see why they are the subject of such scrutiny.

About the size of a small German shepherd, the coyote weighs an average of 25 to 40 pounds, with long, slender legs, a bushy tail with a black tip, and large ears that are held erect.  While its coat can vary, it is usually grey or buff-colored and its snout is long and slender.  A strong swimmer, the coyote characteristically runs with its tail down, instead of horizontally like foxes or up like wolves and dogs.  Primarily nocturnal and very opportunistic, coyotes will eat almost anything, but in Texas they prefer rabbits, rodents, and insects.  Because coyotes can utilize many different food sources and humans have all but exterminated its main predator, the wolf, coyotes have rapidly spread to all parts of the country, including urban and suburban areas.  

Considered monogamous with pairs living together for several years, coyotes are usually shy and elusive, but are frequently seen individually, in pairs, or in small groups, especially when near food.  A family group, more commonly known as a pack, consists of the parents, their pups, and, occasionally, the previous year's pups.  Male and female coyotes pair up, establish a territory, and breed from mid-January to early March.  Normally utilizing a natural cavity or a den dug by another mammal, they will make the necessary renovations by excavating multiple escape tunnels linked to the surface.  After a gestation period of 63 to 65 days, a litter of five to seven pups is born. During the weeks following the birth, the male will bring food to the family, but the female will not allow him inside the den. Coyotes normally may live from 10 to 12 years.

It is easy to get the impression that an area is overflowing with coyotes when one hears a family’s howls.  It reality, there are probably only 2-6 individuals in a pack!  While some people may find it a bit unnerving, coyotes use howling as a means of communication to tell non-family members to stay out of their territory, to locate one another within their territory, to distract other coyotes away from young pups, and as a means for older pups to practice mimicking their parents.

Due to misconceptions and fears about coyotes, many people don't recognize the beneficial aspects that coyotes contribute to our ecosystem. Predators, such as the coyote, serve a valuable function in keeping prey species in balance with their habitat. Populations of small animals, such as rodents and insects, could increase out of control without predators. Coyotes can reduce the number of small animals that homeowners and gardeners consider as pests. While coyotes may change ecological balances of predator and prey species somewhat, they will not eliminate other species from the environment. Many scavenger animals, such as foxes and vultures, benefit from coyote predation on other animals through increased food availability from leftover carcasses.

Coyotes are naturally afraid of people and their presence alone is not a cause for concern, though they can become habituated to rely on human-related sources of food.  Simple steps you can take to peacefully coexist with them include keeping your garbage and recycling inside and secure until the morning of pickup, closing off crawlspaces under porches and decks, feeding your pets indoors, keeping your pets indoors at night (especially cats and small dogs), and educating your neighbors to do the same.

Like all wild animals, coyotes have a right to inhabit our wild places, including the preserves that border our suburban homes.  If you do your part to help strike a proactive balance between humans and these wild creatures and respect their right to exist, you may well be rewarded with a familial chorus of howls on a moonlit night!

Bag Ladies

Bagworm on Crepe Myrtle

While winter is the time of year when we hang man-made ornaments on our trees and shrubs to commemorate the holiday season, it is also the time of year when nature-made ornaments are most apparent in the landscape.  These ornaments are as widely unique as snowflakes, and their appearance varies with the bits and pieces of leaves, twigs, and bark fragments woven into silken bags in a shingle-like fashion.  They reveal themselves on the bare branches and limbs in winter, and they are created by female bagworms.

Bagworm on Anacacho Orchid Tree

Members of the Psychidae family, there are about 1,350 species of bagworms worldwide, also commonly known as bagworm moths or bagmoths. Although different bagworm species vary slightly in habits and life cycle, bagworms spend the winter months in the egg stage sealed within the bags produced by females the previous fall.  

In late May to early June, very tiny caterpillars hatch, produce a silken strand by which the wind can carry them to new foliage (called 'ballooning'), and construct a tiny conical bag carried upright with them as they move.  During leaf-feeding, the caterpillars emerge from the top of the bag and hang onto the host plant with their legs, sometimes aided with a silken thread. The bottom of the bag remains open to allow fecal material (called ‘frass’) to pass out of the bag. 



By August or September, fully grown caterpillars have developed larger bags, and pupate within them.  Seven to 10 days later, the pupae of the male moths work their way out of the bottom of the bag, and emerge from their pupal skin.  These males have half-inch long clear wings, feathery antennae, hairy black bodies, and they spend their time seeking out a female to mate.  Females, on the other hand, are immobile and stay in the larval stage, do not develop into moths, and remain inside the bags. After mating, the females produce a clutch of 500 to 1000 eggs inside their bodies and then die.    



Bagworm on Juniper

Bags vary in size, up to 2 inches long and about a half inch wide, and are spindle-shaped.  They can be quite ornamental, covered in a somewhat patterned array of bits and pieces of plant matter.  A wide range of broadleaf and evergreen trees and shrubs serve as hosts for bagworm species, including juniper, cedar elm, bald cypress, live oak, persimmon, sumac, sycamore, willow, yaupon, and native fruit and nut trees.  

Since these bags are composed of silk and plant materials, they are naturally camouflaged from predators such as birds and other insects.  While birds can eat the egg-laden bodies of female bagworms after they have died, the eggs are very hard-shelled and can pass through the bird's digestive system unharmed.  This represents yet another way to disperse bagworm species over a wide-ranging area, and helps in creating a whole new generation of bag ladies!

Clever Corvids

Common Raven, Corvus corax

Crows, ravens, and jays are members of the Corvidae family, or corvids for short.  Medium to large perching birds with strong bills and feet, and feathers that are predominately black or blue, they are bold, curious creatures, and are found in a wide range of habitats.  

Corvids are known for their high degree of intelligence in the bird world, especially crows and ravens.  Crows have performed as well as monkeys in psychological tests, and most employ intelligence in their daily routines, such as dropping nuts onto hard surfaces (like roads) to crack them.  Ravens can recognize groups of different sizes up to seven, and often show problem-solving insight when posed with an intriguing new task.  

Corvids are very social birds, with most living in extended family groups year-round.  Groups give the birds an ability to guard one another, and those posing as sentries can warn other birds and wildlife when predators such as hawks and owls are near, sometimes mobbing them and chasing them away.  While corvids are noisy birds with loud, often screeching calls, they are also excellent mimics of other birds, and those in captivity have been shown to mimic even human speech. During the winter, when food can be scarce and the weather harsh, corvids aggregate in large groups at abundant food sources and roost together to stay warm at night.  

American Crow, Corvus brachyrhynchos

Found primarily east of the Balcones Escarpment in our area, the American Crow (Corvus brachyrhynchos) is an all black, thick-necked bird with a straight, heavy bill and a short tail that is squared off or rounded at the end.  Their loud cawing gives them away, and many times you will hear them before you see them.  Highly adaptable, they will live in any open space that offers trees for perching and a reliable source of food.  The Common Raven (Corvus corax) is a very similar-looking all black bird, larger but more slender, and with a wedge-shaped tail.  It is found mainly in the Edwards Plateau west of the escarpment and in far West Texas.  An acrobatic flier, one adult was observed flying upside-down for more than a half-mile, and young birds are often seen dropping sticks and diving to catch them in mid-air.  

Western Scrub-Jay, Aphelocoma californica

Blue Jay, Cyanocitta cristata

While there are two species of jays in our area, they overlap only slightly in range.  The Western-Scrub Jay (Aphelocoma californica) prefers the juniper-oak woodlands of the Texas Hill Country while the Blue Jay (Cyanocitta cristata) inhabits the prairies and grasslands in the eastern part of town.  Gorgeous azure blue above with a slate gray back and light gray breast, Western Scrub-Jays lack the head crest and black barring with white patches on the wings that distinguish them from the Blue Jays.  Both species of jays have a mischievous streak, stealing other birds’ cached food and chasing off smaller birds to steal sunflower seeds and peanuts at feeders.   

Green Jay, Cyanocorax ymcas, this common resident of deep south Texas hasn't made it to Austin - yet.

In the wild, corvids are long-lived birds, often reaching over 15 years of age.  During their lives they clearly learn to act intelligently, and we have yet to determine how intelligence might be distinguished from instinct.  But the more we observe and record their behaviors, the more we can appreciate and enjoy these clever corvids!