Monday, July 10, 2017

Understanding the Balcones Canyonlands Preserve System

Fall Color in the Balcones Canyonlands Preserve (BCP)

While we are not professionals or employees of the Wildlands Conservation Division, we have volunteered for them for nearly 20 years.  We are Texas Master Naturalists and the authors of two natural history books (with a third in the works).  We also own a private preserve named Woody Hollow that is part of the BCP, and for 10 years have written monthly Nature Watch columns for local neighborhood newsletters.  We have served on the BCP Citizens Advisory Council (CAC) and feel it is important to attempt to set the record straight regarding many of the issues that have been reported regarding the BCP.

In the 1980s, during a conflict that started between land development and enrivonmental conservation, it was discovered that the Golden-cheeked Warbler (GCWA), a bird species that is highly adapted to a very specific and essential habitat in Central Texas, was in peril due to habitat fragmentation and urban sprawl (all GCWAs are native Texans but spend their winters in Central America).  As such, it was listed as a federal endangered species in 1990.  Recognizing that the Austin area was going to continue to grow rapidly (in fact, it has grown over 350% in the last 45 years), the city decided to take action.

In 1992 voters in the City of Austin passed Proposition 10, approving $22 million in bonds for the sole purpose of acquiring and improving lands to be set aside to protect water quality, conserve endagered species, and provide open space for passive public use.  These lands, made up of several tracts in western Travis County, now make up the Balcones Canyonlands Preserve (BCP) System, and are jointly managed and owned by the City of Austin, Travis County, Lower Colorado River Authority, The Nature Conservancy of Texas, Travis Audubon Society, and various private landowers (expressly through permanent conservation easements).  Collectively, activities on these lands are governed by the Balcones Canyonlands Conservation Plan (BCCP) and operated on a permit issued by the U.S. Fish and Wildlife Service (USF&WS).  These activities are carried out by biologists that work for the city or the county, and augmented by corps of specifically trained volunteers.  The preserve system protects 8 endangered species (2 songbirds, 6 karst invertebrates) and 27 species of concern (those becoming increasingly rare).

The endangered Golden-cheeked Warbler (GCWA)

There are several important factors to note regarding the preserve system, which is federally protected.  While this is not intended to be an all inclusive list, it addresses some of the most misunderstood issues and rumors:

The USF&WS permit has several conditions that must be met, and they include total acreage acquired, amount of edge habitat, and number of karst features protected.  Currently, while progress has been made, not all conditions have been satisfied.

While the BCCP and resulting preserve system is the first of its kind in the nation (i.e. made up of several distinct tracts managed by a group of partners), it is not the largest preserve in the U.S.

The USF&WS allows for a concept called ‘take’, a federal term for harm, habitat damage, or other impacts to a species survival.  Developers must pay a fee and donate alternate and suitable acres of habitat commensurate with the acres of habitat they intend to ‘destroy’.  A key point is that the official agreement states that setting aside the 30,000+ acres of preserve was mitigation for allowing 70% of the GCWA’s habitat (non-preserve land) to be developed.  As such, this agreement would be breached if any kind development or other use were allowed in the preserve system.

There has never been an official promise by any authority to ‘open up the preserve to the public’.  In fact, ‘passive public use’ refers to the grandfathering of BCP several tracts included in the overall system that have always allowed public use: Barton Creek Greenbelt, Bull Creek Greenbelt & District Park, Commons Ford Park, Emma Long Metro Park, Mt. Bonnell Park, St. Edwards Park, Stillhouse Hollow Preserve, and Wild Basin.  These ‘public use’ tracts comprise 30% of the overall preserve acreage.  Additionally, unlike these public tracts, there are very few (if any) trails on many of the other preserve tracts closed to the public.  Two of the best ways to see some of these tracts is to sign up for a guided hike or sign up to become a volunteer (

Some of the larger preserve tracts that were deeded over to the City of Austin carried with them the legal requirement that they would not ever be open for public use.

Studies are being performed continually on preserve lands to understand what is necessary to optimize conditions for protected species.  For example, data has implicitly shown that the GCWA requires closed canopy and a mix of mature, unfragmented oak-juniper woodland for breeding and nesting success.   Care needs to be taken regarding publicly reported studies regarding the GCWA; many have been proven to overestimate current populations due to incorrect assumptions in the models and/or study constructs.  Additionally, several factors will determine success, including but not limited to the number of acres of protected habitat, long-term viability of the GCWA population, and the genetic diversity of that population.

Fences have been erected to protect preserve boundaries due to vandalism by neighbors and encroachment on preserve property (fence cutting, tree cutting, trail creation, homeless camps, etc).  Two notable examples include the high-profile River Place trail closure, where a section of the trail was constructed on preserve property with no authorization, and a neighbor in Jester Estates who was arrested by the police after being given a cease and desist order for cutting down large sections of trees in the preserve adjacent to his property (twice!).

The city and the county have been very attentive to recent concerns about wildfires, and have implemented shaded fuel breaks on urban-wildland interfaces.  Note that increasing human use of preserves would likely increase the chance of human-caused fires and other management issues.  One such issue is the management of feral hogs.  They are of increasing concern and elimination efforts would be such more complicated if tracts were open to public use.

Oak - Juniper Woodland is essential habitat for the GCWA

The benefits of the preserve system are not one-sided.  For humans, it protects our natural heritage by offering sanctuary to a wide array of native plants and animals unable to adapt to urban and suburban development.  Keeping the vegetation healthy helps minimize erosion, moderates urban heat island effects, filters air & water pollutants, and allows rain to slowly infiltrate into the ground to recharge our aquifers.  

One final point.  There is a distinct difference between a ‘park’ and a ‘preserve’.  ‘Parks’ are set aside for people and their recreational activities, while ‘preserves’ are set aside to protect habitat for rare or endangered species as well as the quality of our air and water.  We’re pretty sure most reasonable people would think that’s a fair balance, and one that contributes significantly to the high quality of life here in Central Texas.

P.S. For those who are looking for more trails to use for mountain biking, hiking, and running, consider these excellent alternatives in the area:

Walnut Creek Metropolitan Park (Austin):

Flat Creek Crossing Ranch (Johnson City):

Rocky Hill Ranch (Smithville):

Milton Reimers Ranch Park (Dripping Springs):

Reveille Peak Ranch (Burnet):

Friday, June 16, 2017

Common Centauries

Mountain Pink, Zeltnera beyrichii

As members of the Gentian Family, there are many species of Centaurium worldwide, and three of them are native right here in Central Texas.  The genus was named after the centaur Chiron, famed in Greek mythology for being a great healer through his skill in using medicinal herbs. Herbalists today still use the extract from certain species in this genus, commercially often called ‘stomach bitter’, to aid in the process of digestion.  More recently, molecular studies have reclassified the genus, and the species that belong to the ‘Texas group’ have been renamed Zeltnera.

Mountain Pink (Zeltnera beyrichii), also called Meadow Pink, Catchfly, or Quinineweed, is an annual herb less than a foot tall and best described as a neat bouquet of small, pink flowers. Blooming May through July, Mountain Pink sprouts up like an inverted cone 8 to 12 inches high, on rocky hillsides, limestone outcrops, and along gravelly roadways.  Its leaves are threadlike and are held below the multiple 0.5 to 1.0 inch wide showy pink five-petaled blooms that provide nectar for moths, butterflies, bees, and other insects.  Pioneers used this plant as a medicinal plant to help reduce fevers, which is the origin for one of its common names.

Lady Bird’s Centaury, Z. texensis

Lady Bird’s Centaury (Z. texensis) is named in honor of Lady Bird Johnson, and is a delicate plant 3 to 7 inches tall with an open, branched habit.  Found in dry, grassy areas of the Edwards Plateau and Blackland Prairies, its leaves are linear and shorten in length on the upper part of the plant. Smaller than the other Centaurium species, its light pink five-petaled flowers bloom June to August, and are only about 0.25 inches wide.

Rosita, Z. calycosum

Rosita (Z. calycosum), also called Shortflower Centaury, Buckley Centaury, or Arizona Centaury, prefers moist, open areas in otherwise dry habitat, along streams, on hillsides, and in prairies and meadows with intermittent drainages.  An erect, branching plant up to 18 inches tall, it has larger, oblong leaves at the base and smaller linear leaves on the uppermost stems. Blooming May to July, the rose-pink five-petaled flowers are 0.5 to 1.5 inches wide, occur in an open array along the stalks, and have distinct, spirally curved, yellow pollen-producing anthers.  Of all three species in our area, this one is a bit less common.

Long used in herbal medicine, today’s science has discovered another interesting pharmacological feature of plants such as Centaurium in the Gentian family.  They naturally produce organic substances called xanthones that exhibit antioxidant properties, which are thought to inhibit microbial infection, inflammation, proliferation of cancer cells, and the aggregation of platelets, among other benefits.  Not a bad resume for these common centauries!

Monday, April 17, 2017

The Zen of Wrens

Carolina Wren, Thryothorus ludovicianus

Wrens are small to medium-sized birds, generally drab in color, typically grayish-brown with barring in the wings and tail.  But oh, when they sing, they have loud, melodious, and often complex songs!  Active and vocal, they frequently carry their tails in an upright position, and have adapted well to the presence of humans.  Some of the species of wrens that can be found in our area include Carolina Wren (Thryothorus ludovicianus), Bewick’s Wren (Thryomanes bewickii), and Canyon Wren (Catherpes mexicanus).

Deep cinnamon brown above and warm buff below, with a white throat and prominent white stripe above the eye, the Carolina Wren is a vivacious bird common in moist woodlands and wooded suburbs.  Males sing year round and are known to have a repertoire of about 32 songs, the most common being ‘cheery cheery cheery!’ and ‘teakettle-teakettle!’ This bird is routinely seen around yards, garages, porches, and woodpiles, often nesting in those same places.  Pairs stay bonded year around, and often raise multiple broods a year.

Bewick's Wren, Thryomanes bewickii

A subdued brown and gray bird with a white eye stripe, gray-white underparts, and a long tail barred with black and tipped with white spots describes the Bewick’s Wren.  It typically flicks its tail from side to side or fans it as it skulks through tangles of branches and leaves, searching for food. Nimble and acrobatic, it often hangs upside down from tree branches and leaves. While it favors dry, brushy areas, it is often found inhabiting gardens, residential areas, and parks.  The male has a repertoire of up to 22 songs, usually beginning with two or more high, quick notes, dropping into a lower, buzzy phrase, and ending on a high trill.  Courting birds normally form monogamous pairs.

Canyon Wren, Catherpes mexicanus

The Canyon Wren has a white throat and breast, chestnut belly, brown back flecked in black, and a bright rufous, barred tail.  It prefers areas with rocky cliffs, canyons, outcrops, and boulder piles but it will often build its nest in stone buildings or chimneys.  This wren has a slightly flattened skull and a vertebral column attached higher on the skull, and these adaptations allow it to thrust its bill forward into tight cracks without bumping its head.  While its repertoire consists of only 3 songs, its most common is an exquisitely beautiful descending cascade of liquid notes.

Wrens are mainly insectivores and are often found hopping about, climbing short walls and tree trunks, or making brief flights to search out and glean insects from crevices and cracks.  In fact, their family name Troglodytidae is derived from troglodyte, meaning ‘cave-dweller’, generally referring to the places in which they forage.  Their fairly long and slender, straight to slightly decurved bills assist them in exploring every nook and cranny for insects and spiders.

This spring, take the time to listen to the highly variable, sweet sounding, rollicking songs of these little birds.  Get in tune with their amusing antics, and discover for yourself the zen of wrens!

Wednesday, February 22, 2017

Three Terrific Trees

Mexican Plum in full bloom
Trees are often planted for their ornamental value, or to provide shade, but there are many other reasons to plant them.  They improve air quality by producing oxygen and storing carbon, which offsets the harmful byproducts of burning fossil fuels.  They can moderate the effects of sun and wind, reduce air conditioning costs, and clean the air by trapping dust and pollen.  Trees can also be credited with increasing property values, lowering our heart rates and reducing stress, and providing shelter and food for many types of wildlife.

In Central Texas, three terrific trees that are native to our area include Escarpment Black Cherry (Prunus serotina var. eximia), Mexican Plum (Prunus mexicana), and Carolina Buckthorn (Frangula or Rhamnus caroliniana).  All three of these trees are medium-sized, deciduous, display fall color, and benefit wildlife by producing fruit.

Escarpment Black Cherry blooms
Escarpment Black Cherry is a distinct variety of Black Cherry, found only on the calcareous soils in our wooded hill country canyons, slopes, and floodplains.  Up to 50 feet tall, this tree is prized for its attractive silvery trunk and branches, five-inch long clusters of showy white blooms that occur in March and April, juicy summer fruits, and vivid yellow to red fall foliage.  While the small dark red to purple-black cherries it produces are edible, the rest of the plant is not, and the cherries are often eaten first by birds.  Several butterflies, including Viceroy, Eastern Tiger Swallowtail, Two-tailed Swallowtail, Red-spotted Purple, and Striped Hairstreak use this tree as their host plant. 

Escarpment Black Cherry fruit
Often called the ‘star of our native plums’, Mexican Plum is easily recognizable in spring, as it is an early bloomer.  Before the leaves appear, white to pale pink, five-petaled flowers cover the 15 to 35 foot tall tree from February to April, and they are extremely fragrant, attracting several species of native bees and butterflies.  Plums up to one-inch wide turn from yellow to mauve to purple as they ripen July through September, and they are edible for humans and wildlife alike.  Thick, five-inch long leaves provide food for the Eastern Tiger Swallowtail and Cecropia Silkmoth, and turn a showy shade of orange in autumn. Mature trunks are a beautiful satiny blue-gray with horizontal striations, typical of most fruit trees.

Mexican Plum fruit
A flowering Carolina Buckthorn
Lesser known is the Carolina Buckthorn, an understory tree 12 to 15 feet tall, with oval, shiny green leaves and small yellow clusters of blooms produced near the leaf stems in May and June. It prefers bottomlands, canyons, and streamsides, and in light shade it is airy and tiered.  Bright red fruits turn to black when ripe, and are relished by many birds and mammals.  The leaves stay green into late fall, turning various colors from yellow-gold to bronze-sienna as the weather cools. Carolina Buckthorn is also the host plant for Spring Azure, Gray Hairstreak, and Painted Lady butterflies.

Carolina Buckthorn berries
Consider adding one or all of these terrific trees to your property.  While the best time to plant trees in Central Texas is in the fall, it’s never too late to plan for future enhancements to your native landscape!

Monday, January 23, 2017

Winter Chorus

Clear and bell-like, consisting of a single, quickly repeated note, the call of the male Strecker’s Chorus Frog (Pseudacris streckeri) is unmistakable.  In the midst of winter, especially in the peak calling season from January to early March, multiple males call at the same time, their alternating notes resulting in an unexpectedly delightful winter chorus rising up from the canyons!

Reaching an adult length of 1 to 1.5 inches, this largest chorus frog is identified by a stout gray, brown, olive, or green body, a dark brown mask-like stripe through the eye and a dark spot under the eye, dark longitudinal stripes along the back, and a deep golden or orange color in the groin. Males are slightly smaller than females and have greenish-yellow vocal sacs.  The genus Pseudacris comes from the Greek pseudes meaning ‘false’ and akris meaning ‘locust’, and is likely a reference to the repeated rasping calls of most chorus frogs, which are similar to and can be mistaken for those of an insect.

Although Strecker’s Chorus Frog is mainly a nocturnal frog, its call can be heard day or night. Males call as they hang on to or sit on vegetation, or from the bank above the water’s surface. Typically feeding on insects, this chorus frog is seen most often in moist woodlands, rocky ravines, near streams or in swamps.  While its range includes portions of Kansas, Illinois, Missouri, Oklahoma, Arkansas, and Louisiana, the individuals in Texas are of the subspecies P.s. streckeri, and occur in most counties in the eastern half of our state.

Aside from its distinctive winter chorus, Strecker’s Chorus Frog is also distinguished by its ability to use its forelimbs to burrow headfirst, unlike other amphibians that typically use their hind legs to back into a burrow.  It burrows deeply in sand or mud and hides under rocks and woody debris to protect itself from heat and predators, emerging mainly after heavy rains. Following these rains, it migrates a short distance to a preferred breeding site.

Strecker’s Chorus Frog is a cold-tolerant, winter breeding frog, breeding anytime between November and March when rains are adequate. While most frogs prefer to breed in flowing water, Strecker’s Chorus Frog prefers still, clear, temporary water bodies such as ditches, ponds, and pools in wet weather creeks.  Females attach their small, jelly-covered clusters of eggs to vegetation below the water’s surface, and the time to hatch, while water temperature dependent, is usually just a few days.  Tadpoles take around two months to transform into adult chorus frogs.  In spring, at a time when most other frogs are just beginning to seek their breeding ponds, Strecker’s Chorus Frogs terminate their breeding activities.

Named after John Kern Strecker, Jr (1875 – 1933), a Texas naturalist and Curator of the Baylor University Museum (renamed the Strecker Museum in 1940 in his honor), this chorus frog with its peculiar and unusual habits and haunting winter chorus might have been a perfect candidate for “Strecker’s Cabinets of Curiosities”!  

If you’d like to see and hear the chorus for yourself, check out the video at

Saturday, January 7, 2017

Flowers of Ice

While many plants can be damaged or killed by freezing temperatures or frost, this varies by the type of plant and tissue exposed to these conditions.  In our region, there is a plant called Frostweed (Verbesina virginica), which is commonly found in low-lying areas near streams, creeks, canyon bottoms, and in dappled shade at woodland edges. 

For much of the year, Frostweed goes unnoticed while it grows tall and leafy, the top of each of its stalks crowned by clusters of small white flowers.  It begins to bloom in the August heat, and continues until first frost, well into fall.  In fact, this leggy plant is a rare late-season nectar and pollen source, as its blooms are a magnet for fall migrating hummingbirds and Monarch butterflies, as well as a host of other insects.

However, it is with the first frost or sub-freezing temperatures that this plant really puts on an unexpected show.  When temperatures dip, the water contained in each plant stem expands, causing the stems to crack.  Via capillary action, more water is drawn through the cracks, freezes when it hits the cold air, and forms long curls of ice, reminiscent of petals of an intricate flower or of a delicate, abstract sculpture.

These very delicate ice forms are fleeting in nature, and can only be found in early morning, as the rising temperature of the day quickly melts them away.

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