The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, May 30, 2004

Book Review
The Butterflies of North America
Ro Wauer, May 2004, The Victoria Advocate, © 2004

The new "Butterflies of North America," a Kaufman Focus Guide by Jim Brock and Ken Kaufman, is without doubt the very best of the numerous butterfly field guides on the market today. This book is a must for anyone interested in butterflies, whether they are a novice or a long-time enthusiast. No other butterfly field guide covers all of North America's abundant species, including those found only in Texas. The authors utilize more than 2,300 images in natural lifelike poses to illustrate the North American butterfly fauna. This is one marvelous book!

The butterflies are grouped by families or subfamilies and all keyed to a pictorial table of contents in the first four pages. This system helps considerably when searching for various species. The illustrations within the pictorial table also provide the novice with a quick first-cut idea of the various groupings. Once a proper grouping is found, the illustrations, almost all from photographs taken in the field, usually include several views of each species. These include a typical view as one might see it in the field, as well as an underside or upperside view not usually visible. At times, when a species may appear somewhat different in various parts of the country, or when males and females look different, two or more images are included. At other times, a grouping will include a look-alike species, such as the Monarchs and Viceroys, to help the user separate those species.

Most of the illustrations are similar to the true size of the actual butterfly, large for the larger swallowtails and small for the smaller blues and crescents. When groupings do not permit the necessary space, an "actual size" silhouette is included in the upper right corner of the page. With rare exceptions, this method works very well. Another valuable technique used with many of the illustrations is a pinlike pointer that points out key field marks. This technique helps one zero in on the field mark(s) that is extremely helpful in identifying a particular species.

Illustrations, however, are only one part of a useful field guide. The other is the text. And the quality of the narratives in this new field guide equal that of the illustrations. The layout of the book includes narratives, along with range maps, directly across from the pertinent illustrations. All of these are well done. They discuss the major characteristics, larval foodplants, as well as other useful information. For example, the text for Rounded Metalmark includes the following: "South Texas only, common in lower Rio Grande Valley, where it flies all year (multiple broods). Difficult to separate from Fatal or Rawson's metalmarks. Forewings may look subtly more rounded, with fringes less clearly checkered." All three are possible in our area.

The range maps are generally very well done, certainly well enough for the majority of regions across North America. For South Texas, however, because it is an area where tropical species often occur as a temporary colonist or stray only, the maps occasionally are less exact. The authors have done an admirable job in addressing this situation by including a dotted line that illustrates the potential larger area. More often than not, they are right on!

Another portion of the Brock-Kaufman book is the introductory section that includes narratives on identifying butterflies, finding butterflies, the butterfly's life cycle, how butterflies are classified and named, and other activities involving butterflies. Instead of being boring, as these topics often are in field guides, the authors have done a remarkable job in keeping the narrative interesting and informative. Another plus!

I am sure that by now that the reader is wondering how much such a field-friendly book might cost. And that is still another plus! This 5x7.5-inch book (its fits perfectly in my back pocket), with 384 pages, a plasticized cover, and quality binding, sells for under $25.00. You can't go wrong! All good nature bookstores are selling this class A product!

Cicada-Killers and other Parasitic Wasps
Ro Wauer, May 30, 2004, The Victoria Advocate, © 2004

All the recent talk about cicadas reminds me that all cicadas and all other insects have natural prey that keep their numbers in check. And many of the natural predators are parasitic wasps that without them our world would be a very buggy place.

The largest and most obvious of these wasps are the various spider- and cicada-killers. The best known of these is the pepsis wasps, blue-winged creatures with a red body that can reach two inches in length. The largest one, although rare along the Gulf Coast but far more abundant throughout the southwestern deserts, is known as the "tarantula hawk." A slightly smaller species - Pepsis elegans - with orange wings and a blue body, is far more common in the Central Gulf Coastal area.
These two impressive wasps spend a good deal of time on the ground walking about in search of spiders. Once an appropriate spider is found, it will sting its prey, depositing just enough venom to paralyze but not kill it. When the spider is subdued, the wasp will then carry or drag its prey, depending upon the size of the spider, to a hole that it already has excavated in the ground. It will then cram the spider into the hole, lay eggs in the spider's body, and cover over the hole with the excavated debris. The wasp eggs will hatch within a few days, and the larvae will consume the body of the living spider.

The cicada-killer, known to scientists as Sphecius speciosus, which looks all the world like a huge yellow jacket, is also an effective parasitic wasp. This individual, however, finds its prey above ground in trees. Once it discovered an appropriate prey, it will jab its stinger into the insect's nerve center, paralyzing it. When that occurs, the wasp and prey usually fall to the ground. She will then drag the cicada back up the tree to where she can carry her prey in a direct glide to her burrow. The size of the cicada negates any chance of carrying such a load up and over vegetation, but she has the strength to drag it up an unobstructed tree trunk. Unlike the pepsis wasp, which lays numerous eggs in the body of a spider, the cicada-killer deposits a single egg on the body of the paralyzed victim. And since its burrow usually contains several chambers, it takes several cicadas before its chores are complete.

None of these adult wasps actually feed on their prey. Instead they utilize sap or nectar from flowers. The wasp larvae, however, remain underground feeding on their victim for several days until they reach full size and their food is depleted. Then, rather than emerge as adults, they spin a silken cocoon in which the larvae remain and develop until the following season. Finally, in summer of the following year, they emerge from the cocoons and leave the burrow as adult wasps. And the process begins all over again.

Sunday, May 16, 2004

Thunderstorms are Marvelous Examples
of Nature's Power
Ro Wauer, May 16, 2004, The Victoria Advocate, © 2004

Because of the abundant examples of storms we have experienced in recent weeks, I am repeating a nature note on thunderstorms that appeared in the Advocate on September 13, 1998. It is worth repeating:

Building storm clouds display Mother Nature's immense power and can be counted among one of the most awe-inspiring sights on earth. Thunderstorms represent violent movements of air. They occur as a result of strong uplifting drafts that sometimes build the clouds to heights in excess of 75,000 feet.

Meteorologists tell us that thunderstorms develop in three stages. First, small cumulus clouds build into larger masses of billowy, mushroom-shaped clouds called cumulonimbus, the familiar thunderheads that can be seen for more than 100 miles. Second, when the ascending air reaches a low enough temperature, precipitation occurs. Tiny water droplets are blown wildly around within the clouds until they join together to form larger droplets that are too heavy to remain in cloud form. Then gravity takes over, and the droplets begin to fall as rain, ice crystals, or snow. Huge downdrafts are created when this occurs as the falling precipitation cools the air below, producing the third stage. The entire cloud then becomes a sinking mass of air and precipitation.

Lightning is an electrical charge within a thundercloud or between it and the earth. Charges between clouds or between clouds and the earth are released when electrical pressure becomes high enough. The first strokes are within a cloud; approximately 65 percent of all discharges occur there or between clouds.

Lightning to the ground starts with a relatively thin "leader" stroke from the cloud and is followed immediately by a heavy return stroke from the ground. A single lightning strike goes back and forth from cloud to ground many times in less than a tenth of a second. A lightning discharge is incredibly powerful - up to 30 million volts at 100,000 amperes - but is very short in duration; hence, the power of lightning has never been harnessed.
The total energy of a major thunderstorm far exceeds that on an atomic bomb. The sudden heat from lightning causes compression of shock waves that we call thunder. The distance of these can be estimated by sight and sound. Light travels at about 186,000 miles per second, and sound travels only 1,100 feet per second, or one mile in a little less than five seconds. You, therefore, can judge the distance of a storm by timing how long it takes for thunder to reach you after you see the lightning flash. If you hear the thunder 40 seconds after the lightning, then you are eight miles from the storm.

The energy of one of our coastal thunderstorms is almost beyond imagination. I can think of few other experiences that demonstrate so vividly the power of Mother Nature.

Sunday, May 02, 2004

A Gray Fox is a Marvelous Creature
Ro Wauer, May 2, 2004, The Victoria Advocate, © 2004

I hadn't seen a gray fox in my yard for several months. But last week one was there nevertheless, and I even was able to watch it for several minutes before it ran off into the adjacent woods. It was obvious why it was named "gray" fox. The entire upper side is gray from the head to the tail, although the snout and the end of the tail are black. And the undersides, including the legs, are a cinnamon color. The legs are short, not like the lanky stature of the larger coyote. And the ears are noticeably smaller, too.

The gray fox, along with the coyote, is one of the most widespread mammals in Texas, residing from the Trans-Pecos to the Gulf Coast and from the Panhandle to the Lower Rio Grande Valley. Its habitat preference differs, however, as the gray fox is a woodland animal and the coyote prefers more open areas. And as its choice of habitats suggests, the gray fox, unlike the coyote, spends considerable amount of time in trees; it is able to climb quite well. Not vertical trunks like a cat, but it does manage to climb into trees with lower branches, and it will often rest and even sleep on larger branches.

The gray fox is the most omnivorous of the canids. Its diet varies from prey like small mammals, such as cottontails, mice and rats, to birds, snakes, frogs, and even insects. And during the fall when berries ripen, or when cactus fruits are available, it can take advantage of that food source as well. A report on the stomach contents of 42 gray foxes in Texas revealed that in late summer and fall, persimmons and acorns dominated its diet with 30 percent, insects 26 percent, small mammals 15 percent, crayfish 14 percent, and chicken and quail only once each. The winter food of a similar number of gray foxes included small mammals 56 percent, insects (primarily grasshoppers) 23 percent, and wild birds 21 percent. And because it spends so much in trees, bird eggs would not be ignored.
In Texas, the breeding season begins in February and continues into March. Three to six pups are born in April or May, after a gestation period of about 63 days. Although the pups are born blind and helpless, they grow rapidly and leave the den within a few weeks. They then seek shelter in rocky and brushy areas. It is during this period when the adults are most likely to be seen in the open as they search their neighborhood for food for their growing families. Their weight can increase from a few ounces at birth to 7 to 12 pounds as an adult; there also is a record 19 pounder.

The gray fox must be ever aware of its surroundings, as it often becomes prey to coyotes and bobcats, both predators that occur in the area. In fact, biologists believe that gray fox populations are generally held in check by predation, principally from coyotes. Plus, wild dogs, especially those in packs, also take their share of gray foxes. And gray fox roadkills by vehicles are not unusual.

Although those of us that live outside the cities and towns only occasionally see a gray fox, it is very likely that a pair or a family of these little canids is a local resident. They are most active at dusk and dawn, but they are not limited to the non-daylight hours. Especially this time of year when they must feed hungry youngsters, they can be active during all 24 hours. If you have an opportunity to watch one of these little wild dogs you will appreciate them even more.