Good Water Ripples Vol 1 Issue 4

Good Water Ripples

Volume I Issue  4                                     August, 2011

From the President’s Desk

It has seemed like an extremely long, hot, dry summer.  The good news is that with the arrival of August we are getting much closer to the first cooling that usually happens in September and early October.  Our July pot luck picnic was a success in spite of the hot weather. Susan brought fans for us and the food was great!  I really enjoyed the presentation about the history of Berry Springs Park. My daughter and I walked the park this week.  It is a little eerie to see the pond and all the springs dried up so thoroughly.  But as Master Naturalists we know that changing weather patterns with droughts and floods are normal in Central Texas.  While I can not tell you when, I can promise that it WILL rain again and that autumn WILL come with its cooler weather.

The spectacle of birds continues at Murphy Park in Taylor. I was out there on Friday night. There were two different couples from out of town that came by my big lens and stopped to talk. They had seen the multitude birds from HWY 95 and had to stop to take a better look. They were amazed when I told them how many species were present. I even had one of Taylor’s police officers stop by to check out my big lens. And I was most happy to see our own Bonnie Sladek and her husband out checking out the birds.  For the birders in our group, I saw cattle egrets, snowy egrets, great egrets, great blue herons, little blue herons, white faced ibis, cormorant, juvenile white ibis, whistling ducks, as well as some other assorted domestic ducks and geese. 

I have heard from one of my friends that the Eckert Bat Cave near Mason is well worth the trip.  I know that the drive up the James River Road  to get to the bat cave is beautiful in the spring both for the terrain and for the wildflowers.  This time of year the wildflowers will be nonexistent but the drive should still be pretty with the hills.    My friend told me that the viewing area at this cave is very, very close to where the bats emerge giving excellent viewing.  This is one of the largest bat nurseries in the country with 4 million bats.  I’m hoping to get over there before the summer is over. 

At our August meeting Eric Nuner, the Assistant Director of Parks and Recreation for the City of Georgetown, will be our speaker.   I am eager to hear about the various park programs and to see what volunteer opportunities there are for us.

The Williamson County Audubon Group will meet on August 15, 7:00 p.m. at the New Church, 373 County Road 245, in Georgetown (west of Sun City) with David Shackelford as speaker.  Topic will be “Finding the World’s Birds – Adventures in International Travel.”  He has a life list of 8,000 birds from more than 150 countries. 

Feature article


Mexican Free-Tailed Bats by Mary Ann Melton 

Thirty one of the forty seven species of bats found in the United States are found in Texas.  The Mexican free-tailed bat (Tadarida brasiliencis mexicana) is the most common bat found in the state.  The bats emerging from nursery colonies found throughout Central Texas provide great opportunities to see millions of bats depart their daytime roosts and head out for their nightly feeding. While many bat species roost in caves, Mexican free-tailed bats have adapted well to the urban environment, finding bridges to be an ideal environment to raise their pups. 

Austin boasts the largest urban bat colonies. Bats live in the I-35 bridges at Wells Branch and Howard Lane in Pflugerville and the McNeil Bridge in Round Rock. The McNeil Bridge has approximately 1.8 million bats in residence. The Congress Avenue Bridge is a popular viewing spot with approximately 1.5 million bats..  Bracken Cave just north of San Antonio has the largest bat colony in the world with 20 million bats. It is owned by Bat Conservation International with member only viewing nights.  Old Tunnel Wildlife Management Area is an interesting old railroad tunnel east of Fredericksburg. 3 million Mexican free-tailed bats as well as a different bat species, the cave myotis call this tunnel home. . The upper deck is open 7 days a week. It is possible to take the short trail to the entrance of the tunnel on Thursdays through Sundays and there are educational presentations and the lower deck is open. The Eckert James River Bat Cave Preserve is located along the scenic James River Road near Mason. It is owned by the Nature Conservancy.  Four to six million bats are in residence. It is open Thursday through Sunday with an excellent viewing area  close to where the bats emerge.

Mexican free-tailed bat eat an amazing number of insects each night. A million bats consume 10 tons of insects each night, greatly reducing the need for pesticides.  They provide a special benefit to the agricultural communtiy by eating such insect pests such as corn earworm moths. 

Wintering in Mexico, Mexican free-tailed bats begin arriving in Texas in February. And continue to arrive through April.  Pups born in June stay in the roosting area while the mothers search for food each evening. The pups roost in densities of up to 500 per square foot.  An amazing sense of smell and hearing allow the mother to find her pup by the scent and call.  In wet years, the mothers stay close to the roosting area, but in dry years mothers  go much farther to forage.  The pups begin their flights in late July. August offers the best viewing as the pups have been weaned and join the parents on the nightly flights searching for insects.  Male bats live apart in much smaller bachelor colonies.

The timing of the bat exodus varies throughout the summer and is affected by heat and humidity.  For best viewing, plan to arrive well before sunset and wait patiently to view the beautiful spiraling exit flights. The show can last for an hour or more.

Bats are not a threat to humans, but there are some important safety issues. A bat on the ground or a bat that allows a human to approach is not a healthy bat and should not be touched because it can have rabies.  It is also better to use low voices and avoid the use of bright lights or flash to avoid disturbing the emergence patterns. 

Bats in the Military

Man has even found ways of making bats useful in the military. During World War II the following experimentation was carried out using Mexican free-tailed bats.

Bats Away! By Sterlin Barton

Dental surgeon Lytle S. Adams submitted a plan to the White House in January, 1942, to release “bat bombs” over Japanese cities with industrial targets.  Attached to each bat would be a small timed incendiary bomb.  The bats would spread far from their point of release, and at dawn would hide in widely scattered buildings.  Shortly thereafter built-in timers would ignite the bombs, causing widespread fires and chaos.  President Roosevelt was impressed with the idea and approved it for further study.  Adams and a team of naturalists were immediately authorized to find bats for experimentation. The team visited a number of likely sites in Texas and New Mexico where the bats could be found in large quantities — mostly in caves, but also under bridges, in barns and in large piles of rubbish. The team first investigated the mastiff bat, which they determined could carry a 1-pound stick of dynamite. But there was not a sufficient number of that variety available. The more common bat was the mule-eared or pallid species, which could carry 3 ounces. However, the naturalists concluded that the species was not sufficiently hardy for the work that needed to be done.  They finally settled on the Mexican free-tail bat for the project.   Although it weighed only one-third of an ounce, experiments showed that it could fly fairly well with a payload of 15 to 18 grams.

The project was considered serious enough that Louis Fieser, the inventor of military napalm, designed incendiary devices to be carried by the bats.   It was envisioned that ten B-24 bombers flying from Alaska could release 1,040,000 bat bombs over the target—the industrial cities of Osaka Bay.  A series of tests to answer various operational questions were conducted.  In one incident the Auxiliary Army Air Base in Carlsbad, New Mexico, was set on fire when armed bats were accidentally released and they roosted under a fuel tank. Following this setback, the project was relegated to the Navy in August 1943, who renamed it Project X-Ray, and then passed it to the Marine Corps that December. The Marine Corps moved operations to the Marine Corps Air Station at El Centro, California. After several experiments and operational adjustments, the definitive test was carried out on a mockup of a Japanese city built by the Chemical Warfare Service at their Dugway Proving Grounds test site in Utah.

Observers at this test produced optimistic accounts. The chief of incendiary testing at Dugway wrote:  “A reasonable number of destructive fires can be started in spite of the extremely small size of the units. The main advantage of the units would seem to be their placement within the enemy structures without the knowledge of the householder or fire watchers, thus allowing the fire to establish itself before being discovered.”  The National Defense Research Committee (NDRC) observer stated:  “It was concluded that X-Ray is an effective weapon.” The Chief Chemist’s report stated that on a weight basis X-Ray was more effective than the standard incendiary bombs in use at the time. “Expressed in another way, the regular bombs would give probably 167 to 400 fires per bomb load where X-Ray would give 3,625 to 4,748 fires.”

More tests were scheduled for the summer of 1944, but the program was cancelled by Fleet Admiral Ernest J. King when he heard that it would likely not be combat ready until mid-1945. It was thought that development of the bat bomb was moving too slowly, and was overtaken in the race for a quick end to the war by the atomic bomb project.  By that time it was estimated that $2 million had been spent on the Project X-Ray.

Dr. Adams maintained that the bat bombs would have been effective without the devastating effects of the atomic bomb.  He is quoted as having said:  “Think of thousands of fires breaking out simultaneously over a circle of forty miles in diameter.  Japan could have been devastated, yet with small loss of life.”

And further back in time and closer to home…

Civil War armaments

In the early 1860s Thomas Anderson, who came to Texas from Virginia in the 1850s, built a mill to make gun powder for the Confederacy. It was not until after the war that the mill was converted to a gristmill. Bat guano was an important ingredient in the making of gun powder and an amble supply was found locally in the numerous caves in Travis and Williamson Counties.

As the saying goes: in the making of bacon and eggs, the chicken is involved but the pig is committed. In the making of gun powder the bat is involved but in “bat bombs” the bat is committed.

Species of the month by Wayne Rhoden



This month’s species is the insect praying mantid, or as many of us say, praying mantis. This insect is a master of disguise on plants and is a very beneficial pest management tool for flies, crickets and moths. However they will also feed on honey bees and themselves. They are not effective for control of aphids, mites or caterpillars. They get their name from the way nymph and adult mantids hold their front legs as in prayer. Those legs are used for grasping and holding prey. The adults are green to grayish brown, have well developed wings and are 2 to 4 inches long. Egg masses of the common Texas species such as the Carolina mantid, Stagmomantis carolina (Johannson), are somewhat rectangular in shape, usually about 1 inch long, 1/8 in wide, with rounded sides.  Each mass contains dozens of eggs encased in a frothy material produced by the female that hardens and is tan or occasionally white on top with darker sides.

The species most commonly sold by suppliers for biological control, the Chinese praying mantid, Tenodera aridifolia sinensis, does not occur naturally in the state.

Life cycle: In the fall, adult female mantids lay eggs on twigs, vines and other sites such as under eaves of homes. Eggs hatch in the spring. Nymphs develop through several wingless stages (instars) before becoming sexually mature winged adults. Only one generation is produced per year

Did you Know


There is no such thing as a baby butterfly.

There are five species of fire ants native to Texas.

Recent  trip to California by Winnie Bowen


California redwoods




            Once, not so long ago, redwood forests spanned much of the northern hemisphere.  Now they remain in a few distinctive geographic regions, mostly along a 500 mile belt of Northern California and Southern Oregon.

            The giant redwoods tower 300-feet, the height of a 35-story skyscraper, and may be 2000 years old!   Untouched redwood groves stagger the senses with their size. A lovely grove of giant redwoods produces a sense of peace and reverence. They are the tallest trees in the world.

A half-hour south of Eureka, California, the Avenue of the Giants – a world-famous scenic drive, is by far the most outstanding display of giant trees in the California redwood belt.  It is surrounded by Humboldt Redwoods State Park, which has the largest remaining stand of virgin redwoods in the world. This 31-mile portion of old Highway 101 runs parallel to new Highway 101 and is truly a magnificent drive! The road has frequent pull-offs, also allows easy access to many hiking trails, and even is close to a drive through tree.  (It was a tight squeeze for our Ford Flex.)  The road is a narrow two-lane, pave and well maintained road. The last few miles are a constant up and down, hair-raising, stressful corkscrew road with many curves greater than 200 degrees.

Actually there are three species of redwoods.

The Dawn redwood was thought to be extinct until 1944 when it was rediscovered in an area of China where it continues to thrive. It is a popular ornamental and easily distinguished from its California relative by its smaller size and deciduous leaves. It grows 140-feet tall, has a diameter of 6-feet and produces a large olive-size cone.

The Giant Sequoia is quick growing, long lived and is the most massive tree in the world. Some are thought to be 3000 years old. Sequoias are evergreens and produce a chick-egg-size cone.

Coastal Redwoods are the tallest trees in the world and are found in dense forest stands in nutrient-rich soil. Coastal fog keeps the trees moist. The evergreen tree has a distinctive bark with lines running vertical. The wood is reddish.

            Coastal fog is generated by interaction of cool ocean temperatures and warm summer air inland. Northern pacific coast warming due to increased temperatures caused by global warming has decreased upper elevation fog.

            Scientists are studying the long term effect of reduced fog, warmer temperatures and higher concentration of greenhouse gases on redwood ecosystems. Preserving remaining ancient coastal redwoods in parks is important for the health of life everywhere. These super trees store more atmospheric carbon, a leading contributor to global warming, than any other living thing.


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