Sunday, December 4, 2016

The Preserves Around Us

Golden-cheeked Warbler, Setophaga chrysoparia
One of the main reasons Austin is such a wonderful place to live is because it is interlaced with a patchwork of preserves, which together comprise the Balcones Canyonlands Preserve (BCP) System.  In 1992, voters in the City of Austin passed Proposition 10, approving $22M in bonds for the sole purpose of acquiring and improving lands to protect air and water quality, conserve endangered species, and provide open space for passive public use. Jointly owned and managed by the City of Austin, Travis County, the Lower Colorado River Authority, the Nature Conservancy, the Travis Audubon Society, and private landowners, the BCP’s ultimate goal is to set aside 30,428 acres that contribute to the quality of all life here in Austin. 

A multi-agency conservation effort that operates under a regional permit issued under the Endangered Species Act by the U.S. Fish & Wildlife Service, the BCP consists of several tracts of land in western Travis County.  It is important to note that a ‘preserve’ is different than a ‘park’, and is set aside for the purpose of maintaining a natural state rather than developed for recreational use.  The BCP protects prime habitat for the endangered Golden-cheeked Warbler, a bird species that is found only to breed within Central Texas’ specialized mix of native, mature Ashe Juniper (often incorrectly called ‘cedar’) and stands of Live, Spanish, and Shin oak trees.  This type of mixed oak-juniper woodland grows mainly on our moist steep-sided canyons and slopes, providing the warbler with the food, water, and nest-building material it needs to breed.  

Black-capped Vireo, Vireo atricapilla
In addition to the Golden-cheeked Warbler, 7 other endangered species make the preserve system their home, including the Black-capped Vireo, Tooth Cave Ground Beetle, Tooth Cave Pseudoscorpion, Tooth Cave Spider, Kretschmarr Cave Mold Beetle, Bone Cave Harvestman, and Bee Creek Cave Harvestman.  These last 6 species are called karst invertebrates, arthropods that spend their entire existence underground in karst formations.  These karst features, such as caves, sinkholes, cracks, and crevices, were formed by the dissolution of calcium carbonate in limestone bedrock by mildly acidic groundwater.  Over 70 other rare plant and animal species also exist on the preserves, making this region one of the most biologically diverse areas in the country. As such, Central Texas is happily home to more habitat conservation plans than any other region in the United States.   

These wild and beautiful areas require management plans in order for them to remain pristine habitats.  This includes establishment of secure boundaries and rules for access control, maintenance of appropriate trails, species monitoring, habitat enhancement, and – last but not least – public education and outreach to promote good neighbor relations.  As Austin residents, we can do our part to become stewards of these unique habitats.  While in the preserve system, we can stay on marked trails, travel only on foot, and “take only photographs, leave only footprints.”  In our neighborhoods, especially those that border preserve tracts, we can landscape with native plants, remove invasive plants, eliminate pesticide use, be responsible pet owners, practice water conservation, and always respect preserve boundaries.

Most importantly, we can all minimize further negative impacts on the fragile habitat that surrounds our neighborhoods by caring for the preserves through volunteering.  Some of the activities you can become involved with in the preserve system include long-term habitat restoration, gathering and planting native seeds, removing non-native invasive plants, leading guided hikes, and learning about and sharing your knowledge of the native plants and animals that make this such a special place to live.  For more information, visit the Balcones Canyonlands Preserve website at  

Monday, September 26, 2016

Discovering Blacklighting

A large Polyphemus Silkmoth, Antheraea polyphemus, is always a 
welcome visitor.

Lepidoptera is the order of insects that includes both butterflies and moths.  While over 180,000 species of these insects have been identified worldwide, recent estimates suggest that this order may have more species than previously thought, and is among the four most speciose orders, along with Hymenoptera (sawflies, wasps, bees, & ants), Diptera (true flies, mosquitoes, gnats, & midges), and Coleoptera (beetles).  Of the approximately 180,000 known Lepidoptera species, some 160,000 are moths, with nearly 11,000 of them found in the United States, and many are yet to be described.

The Imperial Moth, Eacles imperialis, is another silkmoth that may 
come to a blacklight in Central Texas.

Carolina Sphinx, 
Manduca sexta

Small Heterocampa Moth, 
Heterocampa subrotata

With such huge numbers and such a diversity of species, how does one go about studying moths? A good place to start is while knowing that most moths are creatures of the night, they are also attracted to light.  The reason for this behavior is unknown, although one theory is that moths use a form of celestial navigation called transverse orientation.  They attempt to maintain a constant angular relationship to a bright celestial light, like the moon.  But since the moon is so far away, and the angle change is negligible, the moth appears to travel in a straight line.  This theory is tested when moths fly near much closer sources of light, such as a porch light or a campfire.  The angle to the light source changes constantly as the moth flies by, so the moth instinctively attempts to correct it by turning toward the light, thereby producing its erratic flight.

Cellar Melipotis, 
Melipotis cellaris

Giant Leopard Moth, 
Hypercompe scribonia

White Palpita Moth
Stemorrhages costata

Cisthene unifasc
Melonworm Moth, 
Diaphania hyalinat

Paler Diacme Moth, 
Diacme elealis
Eggplant Leafroller Moth, 
Lineodes integra

Ragweed Plume Moth, 
Adaina ambrosiae
Swag-lined Wave, 
Scopula umbilicata
Southern Emerald Moth, 
Synchlora frondaria

One way for the moth to keep a constant angle to a stationary light source is by becoming stationary itself, effectively being ‘trapped’ by the light rather than ‘attracted’ to it.  Those interested in studying moths have taken advantage of this fact, and have developed a method called blacklighting to attract and photograph moths.  The first step is to set up a light source, and either an ultraviolet light (also known as a blacklight) or a mercury vapor  light can be used. Mercury vapor is now the preferred source, as it provides a different spectrum of light than a blacklight, although a blacklight emits a greater spectrum of light.  Moths can see waves of light that humans cannot, so providing them with different spectrums will generally produce the greatest response. The light is carefully hung or positioned in front a vertical white sheet, which the light bounces off to produce a big, concentrated, glowing mass, while also providing a safe surface for the moths to land.

The blacklighting setup is positioned out of the wind and typically near a boundary between wooded and open areas.  The light is turned on at dusk and left on all night, as different species of moths are most active at different times.  After taking the desired photographs with a digital SLR with a macro lens and flash, the light is turned off and the sheet is given a vigorous shake to scatter the remaining moths.  After all that was done to ‘capture’ them with light for observation and photography, it would be a shame for them to become easy  quarry for insect-eating birds or other predators!   

Another opportunistic predator at a blacklight is this Mediterranean Gecko, which 
has captured an Underwing moth.

Friday, August 5, 2016

Sun Trackers

This time of year, the most notable family of plants are the Heilianthus, or sunflowers.  From the Greek ‘helios’ or sun and ‘anthos’ or flower, these plants are usually tall annuals or perennials that during their growth phase exhibit a subtle behavior in the daylight hours.  This behavior, called heliotropism, is the ability for the young flower buds and leaves to gently tilt toward the sun, tracking it as it moves across the sky. By the time the flower heads mature, they are stationary but generally facing east to greet the rising sun.

Sunflowers are typically tall plants with one to multiple flower heads, consisting of bright yellow ray florets or flowers, surrounding yellow or maroon disc florets.  In wild or native species, the rough and hairy stems are normally branched, and the leaves are often sticky and lance or heart-shaped. Sunflowers also exhibit phyllotaxis, or the arrangement of leaves on a stem that forms a distinct pattern, in this case a repeating spiral.  Additionally, the disc florets also display a phyllotactic pattern, one that creates the optical effect of criss-crossing spirals in the flower’s center.

Common Sunflower (Helianthus annuus)
In our area, the two most abundant sunflowers are the Common Sunflower (Helianthus annuus) and the Maximilian Sunflower (Helianthus maximiliani).  Blooming from May to October, the Common Sunflower grows on dry soils, especially in disturbed areas.  It can reach 1.5 to 8 feet tall, and various parts of the branched stems can be either green or dark purple.  The heart-shaped leaves are coarse and covered in rough hairs, and grow from 2.5 to 10 inches long.  Up to 4 inches across, the flower heads have yellow ray flowers and reddish brown disc flowers.  As their scientific name suggests, these plants are annuals.

Maximilian Sunflower (Helianthus maximiliani)
Maximilian Sunflowers, on the other hand, are perennials that bloom in September and October. They grow 1 to 6 feet tall in colonies on both the dry ground of prairies and the moist ground of roadside ditches and other low places.  Shorter, rough hairs cover the narrow lance-shaped leaves, which average 2 to 4 inches long.  The 1.5 to 3 inch wide flower heads have yellow ray flowers surrounding yellow disc flowers, with numerous flower heads growing along the unbranched stems.

Aside from their aesthetic value to humans, sunflowers are generally palatable to deer and numerous species of birds eat their seeds.  Their flower heads support nectaring bees, and they are the food plants for several butterfly species such as the Bordered Patch and Silvery Checkerspot.  When mixed with other native annuals, these sun trackers provide good cover for many species of wildlife, and would be a great addition to your native wildscape.   

Friday, July 1, 2016

Summer Sulphurs

Orange Sulphur, Colias eurytheme, on Indian Blanket

The family of butterflies known as Pieridae includes the whites and sulphurs, our most conspicuous and abundant butterfly species. They easily draw the attention of even the most casual observer as they flit about our gardens, fields, and open habitats in summer.  Sulphurs are usually some shade of yellow, orange, or white, and avidly visit flowers.  Their uppersides often feature black borders or patterns and while they usually perch closed, these patterns can sometimes be seen faintly through the wing or glimpsed in flight. The most widespread sulphurs in our area include the Orange Sulphur (Colias eurytheme), Southern Dogface (Zerene cesonia), Little Yellow (Pyrisitia lisa), and Dainty Sulphur (Nathalis iole).  

Orange Sulphur, Colias eurytheme
White Female Orange Sulphur

Found throughout most of North America, the coloration of the Orange Sulphur can be quite variable, but the typical male has a yellow upperside with orange overlay, yellow veins, a wide black border, and a dark black cell spot.  Females can be yellow or white with an irregular black border surrounding several light spots.  Both sexes have a silver spot surrounded by two concentric dark rings and a spot above it on the underside of the hindwing. With a wingspan of about 1.5 to almost 3 inches, males patrol around for receptive females, who lay eggs singly on the leaf tops of host plants in the pea family, such as alfalfa and clovers.  Orange Sulphurs have 4 to 5 broods from March to November, and overwinter in the chrysalid form.

Southern Dogface, Zerene cesonia

The Southern Dogface is easily identified by both sexes having the shape of a yellow dog’s head surrounded by black on the upperside of their forewings, with the black and white ‘eye’ not touching the black border.  The underside of the hindwing in summer is pale to bright yellow, becoming tinged with pink markings in the fall.  With a wingspan of 2 to 3 inches, the males seek out females who lay eggs on the undersides of terminal leaves of host plants such as alfalfa, clovers, and indigo.  Three broods are produced almost year round, with adults overwintering in reproductive arrest during the coldest months.

Little Yellow, Pyrisitia lisa

As their name suggests, Little Yellow butterflies are on the small side with a wingspan of 1 to 2 inches.  The upperside of the male has a yellow forewing with a wide black tip or apex and a hindwing with a black border. While the female is usually yellow and sometimes white with black borders, both sexes usually have two tiny black dots at the base of the hindwing underside.  Four to five broods occur in the south, and females lay eggs singly on midveins or between leaflets of partridge pea, wild sensitive plants, and sennas.

Dainty Sulphur, Nathalis iole

A mating pair of Dainty Sulphur in winter form

Our smallest sulphur, the Dainty Sulphur, has a wingspan of ¾ to slightly over 1 inch, and is identified by a yellow upperside with black markings that are more extensive on the female.  The underside of the forewing has an orange or yellow patch near the base with a few strong black spots closer to the outer wing edge.  In summer, the hindwing underside is pale yellow, and turns to dusty green in winter.  Both males and females tend to fly low, rest with their wings closed and held perpendicular to sun’s rays to gather warmth, and overwinter in adult form.  Flying year round, the females lay single eggs on sneezeweed, dogweed, and other asters.
Send your nature-related questions to and we’ll do our best to answer them.  Check out our book, Nature Watch Austin, published by Texas A&M University Press, and our blog at if you enjoy reading these articles!

Tuesday, April 19, 2016

Mud Hens

American Coot, Fulica americana

Spend any amount of time observing wildlife around freshwater wetlands, swamps, marshes, suburban lakes, and sewage ponds, and you’ll no doubt see a Mud Hen or American Coot (Fulica americana).  Commonly mistaken to be ducks, coots belong to a distinct scientific order and differ significantly from other species of marsh birds.

An overall blackish, plump, chicken-like bird with a rounded head, red eyes, a sloping whitish bill with a dark band near the tip, and a small reddish brown forehead shield, coots swim like ducks but do not have webbed feet like ducks.  Their yellow-green legs end in long toes with broad lobes of skin on either side that help them kick through the water.  Each time the bird lifts its’ feet, the lobes fold back to facilitate walking on dry land.  Their tiny tails and short wings make them awkward and clumsy fliers, and they often require many wing beats and long running takeoffs to get airborne. Coots mainly eat aquatic plants and can dive in search of food, but they can also forage and scavenge on land for terrestrial plants, arthropods, fish, insects, and mollusks.  

Note the lobed feet on this perching American Coot

Mating season occurs in May and June, with coots requiring heavy stands of aquatic vegetation along a shoreline with some standing water within those stands.  It is here that they make their nests, which consist of multiple structures used as display platforms, egg nests, and brood nests. Egg nest material is woven into a shallow basket and lined with finer grasses to hold the eggs. The entire nest is anchored to upright plant stalks and is generally a floating structure.  Females deposit eggs between sunset and midnight, one per day, until the average clutch of 9 eggs is complete. Both males and females share the 21-day incubation responsibility.  

Being persistent re-nesters, coots will replace lost clutches within 2 days during the deposition period.  Additionally, once hatching begins and a certain number of chicks are present, coots will abandon the remaining eggs.  Unlike the drab color of the adults, coot chicks are quite colorful, having conspicuous, orange-tipped, ornamental plumes covering the front half of their bodies, often referred to as ‘chick ornaments.’   While these plumes get bleached out after about 6 days, experiments have shown that chicks with more of this ornamentation are given preferential treatment by their parents. The oldest known coot lived to be more than 22 years old.

In winter, coots can be founds in large groups or ‘rafts’ of mixed waterfowl and in groups numbering thousands of individuals.  They can consume very large amounts of aquatic vegetation, but because they live in wetlands, they can accumulate toxins from pollution sources including agricultural runoff, industrial waste, and nuclear facilities.  As such, scientists monitor coots as a way of measuring the effect these toxins have on the health of the environment at large.   

Thursday, February 11, 2016

Fabulous Foxes

Gray Fox, Urocyon cinereoargenteus

Members of the Canidae family are all dog-like mammals, and in the United States that includes wolves, coyotes, domestic dogs, and true foxes.  They are adapted to running swiftly over open terrain, and typically have long muzzles, upright ears, bushy tails, and teeth that can crack bones. The family is further divided into two tribes, with the wolves, coyotes, and dogs in the Canini tribe, and the true foxes in the Vulpini tribe.  In central Texas, two species of true foxes exist, the native Common Gray Fox (Urocyon cinereoargenteus) and the introduced Red Fox (Vulpes vulpes).  

Gray Fox, Urocyon cinereoargenteus
Most active at night, and sometimes in late afternoon or early morning, the Gray Fox is a medium-sized fox with grayish upperparts, tawny sides, and reddish-brown legs.  It has a whitish throat with a distinct black patch on the sides of its muzzle and lower jaw.  Often confused with the Red Fox, the main distinction is the black tip on the tail and the fact that it is found throughout Texas.  Gray Foxes are adept tree climbers, highly unusual for Canids, and they use their rounded claws to ascend trees much like bears.  Once up in the canopy, they can hunt birds, escape predators, bask in the sun, or jump from branch to branch like a cat.

Also active at night, and frequently at dawn and dusk, the Red Fox is similar in size to the Gray Fox, but differs mainly in its coloring.  While its typical coloration is generally rusty red, this fox can exhibit several other color forms, from black to silvery gray, but it always has a pattern of darker fur along the spine and down across each shoulder blade, forming a cross.  The most distinct difference from the Gray Fox is the bushier tail that ends in a white tip.  The Red Fox is found throughout most but not all of Texas, absent from the far western and southern portions of the state.  Not native to Texas, it was introduced for sport around 1895 in the eastern and central regions. 

Red Fox, Vulpes vulpes

Both species of fox are social animals, and their primary unit consists of a family with an adult male (or Reynard or dog), adult female (or vixen), and the juveniles (or kits, cubs, or pups) that were born that year.  These foxes are thought to mate for life, with breeding beginning in December and extending into February.   They can use a variety of places for denning sites, but most commonly they reuse underground burrows dug by other animals.  Both the male and female care for and feed their young, and their diets consist of small mammals, birds, berries, and occasionally insects.

Foxes are usually seen in mixed woodlands and edges of forests, and while hunting they often use old roads or open trails while traveling the same routes.  Their activity peaks with the activity of their prey, and if you get the chance to watch the cunning way in which they hunt, using their night vision, acute hearing, and high pouncing attacks, you’ll begin to understand why they are called fabulous foxes!

Saturday, December 12, 2015

Likin' Lichens

A fruticose Slender Orange Bush Lichen, Teloschistes exilis, makes
its home among various foliose lichens.

What lies beneath our feet and in front of our eyes, typically small and unassuming, sometimes brightly colored, but always waiting patiently for their contributions to take hold?  Lichens! Composite organisms made up of a fungus and a photosynthetic partner, most commonly an algae, lichens are ecosystem pioneers.  They break down rock surfaces and prepare areas for mosses, grasses, and trees to follow.  Certain species that also contain cyanobacteria can improve the fertility of the soil by adding necessary, usable nitrogen, and many species are used as bio-indicators of air quality.  They are also highly efficient collectors of airborne substances, and recycle these substances into the soil.  Historical uses for lichens include food, natural dyes, and herbal remedies. 

Mexican Yolk Lichen, Candelina submexicana, is a good example of a crustose lichen.

Lichens can be observed in many places, including on the ground, on rocks, and on trees.  The surface, or substrate, on which they are found provides a place for them to attach and grow.  Some species are substrate-specific while others can grow on a wide variety of substrates.  Ground substrates can include sand, soil, mosses, and downed decomposing logs.  These lichens act as soil stabilizers and contribute to soil fertility.  Rock substrates include natural substances like cliffs, talus slopes, boulders, and pebbles, and man-made substances such as concrete and roof shingles.  Lichens on rock substrates often colonize the rock and act as decomposers, turning it into soil.  Tree substrates include both deciduous trees such as oaks and conifers such as firs, cypresses, junipers, and pines.  Older trees often have a greater diversity of lichens, partly due to a more fissured bark that has a specific texture, chemistry, and moisture-holding capacity.  

Cumberland Rock-shield Lichen, Xanthoparmelia cumberlandia, is a type of foliose lichen. 

Lichens are mostly commonly divided into three growth forms: crustose, foliose, and fruticose. Crustose lichens look like they are spray-painted on their substrate, and their lower surface or ‘medulla’ is the same color as and blends into that substrate.  Foliose lichens are leafy growths with distinct lobes, and their medulla is a different color.  Fruticose lichens are often bushy or shrubby growths, and can be highly variable.  They often form obvious disk or cup-shaped structures called ‘apothecia.’  

Western Antler Lichen, Pseudodevernia intensa,
is a fruticose lichen.
Sundew Beard Lichen, Usnea cirrosa, shows
off its apothecia.

As composite organisms, lichens have been used worldwide as indicators of air quality.  They are very sensitive to the presence of low levels of sulfur, nitrogen, and fluorine-containing pollutants that adversely affect their community composition, growth rates, reproduction, biomechanics, and appearance.  By concentrating a wide variety of pollutants in their tissues, they act as pollution monitors, and are the subjects of many biomonitoring studies regarding air quality and climate change being conducted jointly by the U.S. Forest Service and the Environmental Protection Agency.  Since lichens are long-lived, can be observed in the field in any season, and with many species having extensive geographical ranges, they allow for changes in pollution to be studied over large areas and long periods of time.

As you can see, the lichen has almost all it needs to survive.   While most species of lichens grow very slowly, they all require a proper substrate, clean air, moisture, sunlight, and warmth to thrive. Turning air into life, they are truly one of nature’s alchemists!