The Nature Writers of Texas

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

Sunday, July 30, 2006

Dodder Looks Like Tangled Yellow-Orange Twine
by Ro Wauer

I was surprised on a recent visit to Magic Ridge, a Texas Ornithological Society Preserve near Indianola, about the abundance of dodder scattered along the roadside, some on low-growing shrubs. The larger patches of this odd-looking plant were obvious, but smaller less developed patches were less noticeable. It looked very much more like discarded yellow-orange spaghetti than a living plant. But on closer inspection it was plant with twining stems and tiny flowers.

Dodder has neither leaves nor chlorophyll, but its white flowers are surprisingly attractive. They form small, dense, stemless clusters of tiny tubular and lobed structures that last only a few days. Dodders become most obvious in summer and fall, and the most noticeable part of the plant is the smooth, twining vine that forms mats on the ground or on various host plants. This viney character of fleshy stems has given it a number of descriptive names: angel's hair, love vine, strangleweed, tangle-gut, and witches' shoelaces.

Dodder is a member of a unique family limited to dodders, but is closely related to the sweet potato and morning-glory. Six dodder species are listed in Plants of the Texas Coastal Bend by Roy Lehman, Ruth O’Brien, and Tammy White (Texas A&M Univ. Press, 2005). The huge Manual of the Vascular Plants of Texas, by Donovan Correll and Marshall Johnston (Texas Research Foundation, 1970), includes a total of 23 Texas species. And about 170 species, mostly in the Americas, are known world-wide. Most species are limited to one or a few hosts, and will not live on other hosts, but others will grow on a wide range of herbaceous and woody plants, even grasses.

Dodders are parasitic. They sprout from a seed and initially develop a root system in the soil. The geminating seed produced a twining stem; this becomes parasitic by means of suckers that penetrate the bark of a host species. The stem then withers away, severing its connection to the ground, and the mature plant spends the remainder of its life living on its host. Although this process may take a year or more, the plants are most noticeable in late summer and fall. At times the yellow plants may cover rather larger areas of several yards, but most individuals are less than a couple feet across.

Human use of dodder in the Americas is limited, although Pawnee Indians are reported to have used it in making a colorfast dye to color feathers. And Elizabeth Silverthorne, in her Legends & Love of Texas Wildflowers (Texas A&M Univ. Press,1996), adds that the "Cherokees crushed the stems to make a poultice for bruises, and other tribes used dodder as a contraceptive and also made a bath from it for patients with lung complaints." She added that the "Chinese used the seeds to treat urinary infections. In England it was used to treat urinary complaints and kidney, spleen, and liver diseases."

Silverthorne also stated that the name of love vine was derived from folklore. "It was said that if a man swung a bit of the vine three times around his head and then threw it backwards, he could find out if his sweetheart loved him. After three days, when he returned to the spot, if he found that the dodder had attached itself to another plant and was growing, the person named when it was thrown returned his love, but if the vine had died, that person did not love him. The fact that the vine usually thrives accounts for the popularity of this test."

Sunday, July 23, 2006

Fall Bird Migration Already Underway
by Ro Wauer

It annually seems strange that in July we already are finding southbound migrants passing through our area. It was only a few weeks ago that those same birds were passing through South Texas on their way to their nesting grounds to the north, some as far away as Alaska and above the Arctic Circle. Yet here they are, maybe even the same individuals that we saw in late March or April or May, back again. But that is the way of things in the bird world. In fact, many of our earliest southbound migrants are the ones that traveled the furthest to nest on the northern tundra. They nest early, even when much of their nesting ground is still filled with snow and ice. But because of the extremely long daylight hours in the Arctic summers, they are able to raise their brood much quicker than species further south with shorter days. They are able to finish their family chores before the days begin to cool.

Bird species we are seeing in late July and August, the earliest of the southbound migrants, are often males only. The females often are still tied up with family chores, although they and the young of the year too will soon follow the males. Shorebirds, many of which are Arctic nesters, are some of our most numerous July-August migrants. And hummingbird males are famous for their early arrivals. It is not surprising, for example, to find rufous hummingbird males feeding in mountain meadows of the Texas Big Bend Area and the mountains of northern Mexico by early July. Of course, hummingbird males never attend to family business once mating has occurred. Hummingbird males are included among the most notoriously - promiscuous rakes - in the bird world. After mating they gather in bachelor groups, feed on the abundant flowering plants with other males, until they move southward toward their wintering grounds.

Many of our earliest southbound migrants are those that nested nearby. The purple martin is one excellent example. Those that have nested in our own neighborhoods have completed their families and have either moved on toward their wintering grounds or are staging in favorite locations and preparing to head south together in larger flocks. We also are seeing birds that have nested just out of our immediate area and in northern Texas and adjacent states. A few examples of these include a number of swallows, blue-gray gnatcatchers, northern parulas, yellow-throated and black and white warblers, and indigo buntings.

And a few post-nesting birds that nest in Texas roam in directions other than southward. There regularly are records of various southern species being found considerable distances from the nesting grounds. Imagine scissor-tailed flycatchers in the northeastern states, and various hummingbirds moving north or eastward after nesting instead of southward to their normal wintering grounds. One of the best examples is our very own buff-bellied hummingbird that annually is found in Louisiana in late fall and early winter. This is the same species that has become a full-time resident in Victoria County only during the last dozen years. It is reported in spring and summer more and more often to the north of Victoria County, and it would not surprise me that it would soon become a summer resident throughout most of southeastern Texas, and maybe westward into the Austin area.

Buff-bellied hummingbirds are but one of several birds that have moved northward during the last couple decades. Once only Texas residents in the Lower Rio Grande Valley, buff-bellied hummers, green jays, Couch's kingbirds, ringed and green kingfishers, tropical parulas, and white-tipped doves are on the move northward. It is readily apparent to anyone with an open mind that even we along the Central Texas Gulf Coast are affected by Global Warming. In this case, it can be considered a positive affect.

Sunday, July 16, 2006

Giant Whining Cicadas Are Commonplace This Year
by Ro Wauer

Can anything think of a more appropriate name for this loud cicada? More numerous than anytime in recent years, this large cicada, known to scientists as Quesada gigas, has invaded neighborhoods throughout our area. Although individual adults are seldom encountered, because they usually perch high in the trees, the singing males can hardly be ignored. Their song is amazingly loud and high-pitched. It starts with a stutter and then ends in a sharp, loud whining sound, almost like a high-pitched motor. And it can be heard all day and all night, and even is noticeable from inside the house. One loud love song!

A couple people have asked me about this loud sound, so evident almost everywhere. Although I recognized it as a cicada, it wasn't until I asked Wayne McAlister, first class naturalist and retired professor and biologist, that I finally found someone knowledgeable enough to identify my bug. Wayne also told me that the probable reason that the giant whining cicada is not included in any of the abundant insect books on our area (that I already had poured through) is that our area is at the extreme northern edge of its range, but that it occurs as far south as Argentina. Just one more bit of evidence that our location is at the northern edge of the tropics.

Our giant whining cicada is but one of a handful of cicada species found in North America. But I am sure all my readers will agree it is one of the most obvious of all. Probably, the periodical cicada is better known because it is cyclic, appearing in the South on about a13-year schedule, although broods overlap. The shortest cicada life span is four years. Almost all the cicadas are fairly large insects, some reach two inches in length with a blackish body, some with greenish or reddish markings, four transparent wings, a blunt head with a pair of bulging eyes, and mouthparts adapted for sucking plant juices.

Cicadas are often erroroneously called locust, a type of grasshopper, but cicadas are more closely related to aphids, whiteflies, and scale insects, in the insect Order Homoptera. Although locusts can cause severe damage to crops, cicadas damage some plants only in a very minor way from egg-laying slits in their stems, often causing the tip growth to die.

The cicada life cycle is pretty much the same for all the species. Females deposit their eggs in the twigs of various trees and shrubs. The eggs generally hatch in about a month, and the stout and brownish nymphs drop to the ground where they enter the soil and feed on roots. Eventually, 13 to 17 years for periodical cicadas or four to five years for many other species, they emerge, crawl onto the tree or shrub and molt a last time into an adult and the start of a new life cycle. The hollow casings left behind are often commonplace.

Once an adult has shed its nymphal skin, it moves higher into the trees in search for a mate. The male will serenade the female by vibrating membranes on the sides of its abdomen; females do not sing. Each species produces a unique sound. The high-pitching whining of the giant whining cicada is truly unique!

Sunday, July 09, 2006

Bison, Symbol of the American West
by Ro Wauer

The recent Victoria Advocate article about the number of ranchers raising bison in Texas suggested another topic for a Nature Note, one that I have not previously addressed. Probably because wild bison are not something that can be expected along the Gulf Coast. However, historical bison populations did extend far south in Southwest Texas, into the Marathon Basin just north of Big Bend National Park, and also along the Rio Grande at least eastward to Del Rio. In fact, there is an amazing archeological site near Langtry where native Indians once herded bison over a cliff to kill as many as possible for food, clothing, and other uses.

The Langtry site, named Bonfire Shelter and excavated by University of Texas archeologists in 1963 and 1964, produced thousands of bison and other mammal remains, including some species now extinct. Native horses, camels, mammoth, and antelope were all included, although the vast majority of the remains were bison. Some dated as far back as 11,700 years ago (9700 BC), evidence that even early man utilized native bison. The site name was derived from the abundance of burned carcasses. The decaying mass built up heat and gasses until it spontaneously combusted.

Bison were pretty well extinct before 1900, primarily because the government paid hunters to kill what was a vital link to the survival of Native Americans. The greatest slaughters took place in the 1870s; more than 1500 outfits killed in excess of 100,000 animals in the months of December and January. The last verified report of wild bison in Texas was from the Panhandle in 1889.

The American bison, incorrectly called buffalo by the majority of Americans, is a huge, cowlike mammal with a distinct hump in the shoulder region. A bull can be six feet tall and weigh up to a ton. The wild bison is a gregarious plains animal that lives in herds, although old bulls may prefer a more solitary existence, especially in spring and early summer. But during rut in July and August they become more tolerant of the herd and associate with the ladies. The older, stronger bulls drive off the younger males, and bison are well known for being promiscuous in their mating habits. Calves arrive in April, May or early June, usually one calf at a time but twins can occur occasionally. Sexual maturity is reached in the third year, meaning cows can be productive for up to 40 years. Bison life span is at least 45 years.

The plains bison are predominantly grazers, utilizing grasses and forbs. Because of their diet being so much like the non-native cattle, open range bison are considered as competitors. Unless they are given special protection, as is the case with the various ranchers with a soft spot for these native Americans, bison can no longer exist within our society. That is even though bison meat contains only one-fifth the fat grams as beef, half the calories, less cholesterol, and higher amounts of iron and vitamin B-1. From my personal experience, bison meat is equal to beef, taste-wise, but the current cost cannot help but keep most people from buying bison rather than beef.

But whether or not bison are protected and raised for food, they, more than any other native mammal, truly are the symbol of the American West. The efforts of the few government agencies providing bison protection - places like Yellowstone National Park and Caprock Canyon State Park - and the special interest of a few private citizens are to be commended.

Sunday, July 02, 2006

Grasshoppers Are Fascinating Insects
by Ro Wauer

With the arrival of summer, with its hot and dry days (especially this year), grasshopper populations are on the increase. Although most species begin to appear in mid-spring, others wait to put in their appearance during summer. Some years various species can occur in such large numbers that they can literally destroy their food supply. Farmers can loose much of their crops, including sorghum, corn, soybeans, and cotton. And those of us with gardens, including those designed to attract butterflies, can suffer as well.

Texas has more than 80 species of grasshoppers, and all of those have been included within a recent book, titled "Field Guide to Grasshoppers, Katydids, and Crickets of the United States," by John Capinera, Ralph Scott and Thomas Walker. Published by Comstock Publishing Associates, a division of Cornell University, it includes species descriptions, along with excellent paintings of most species, and up to date range maps. And I found the key to species identification easy to use and most helpful. The introduction section is also well done. It includes good information on features, life history, habitats and food, ecological significance, and biogeography.

Here is a brief listing of some of our local species. The huge, reddish, eastern lubber grasshopper is one of the best known of all grasshoppers. The skinny toothpick-like grasshopper is Sumichrast's toothpick grasshopper. The common mid-sized, green-bodied species is graceful range grasshopper. The large-headed, green species is elegant grasshopper. The mid-sized, brown mottled species is the southwestern dusky grasshopper. Other local species include the three-banded range grasshopper, orange-winged grasshopper, ridgeback sand grasshopper, meadow purple-striped grasshopper, and red-legged grasshopper. Several of these are readily identified by their name.

Grasshoppers, katydids, and crickets are closely related, all lumped by entomologists in the insect order Orthoptera. A major reason for this classification is their life history. Unlike some other insect orders, such as Lepidoptera (butterflies and moths) that undergo a complete metamorphosis, Orthopteras undergo a simple (or gradual) metamorphosis. Their principal life forms include only the egg, nymph, and adult. The nymph and adult forms progress with minimal change in appearance. Grasshopper females deposit eggs (4 to 100) in groups, usually in the soil in a cluster held together by a frothy secretion. As it dries it forms a rigid covering that protects the eggs, collectively known as an egg pod.

Upon hatching, usually in spring, the young grasshopper, called a nymph prior to reaching adult size, simply digs its way through the soil and molts. It is then a walking, hopping, and eating immature grasshopper. Wings develop gradually as the nymph progresses through five or six molts (instars) to reach breeding stage. Their old body covering is shed with each molt.

Typical grasshopper females lay eggs in late summer and fall, the eggs hatch in spring, nymphs develop during the summer, and the adults mate and produce eggs in the summer and fall. The nymphs and adults of some southern species can be found nearly year-round. But most species produce a single generation annually, although the life cycle of more northern or high altitude species take more than one year from egg to adult.

Grasshoppers generally are considered the most abundant aboveground of all insects. And they probably are one of the most important for a number of reasons. Their feeding habitats, especially during eruptive years, can have very significant negative effects upon food crops, and they can actually decimate some habitats. On the other hand, grasshoppers are one of the most important foods for an amazing variety of other animals, from mammals to birds, to reptiles and amphibians, and even other larger insects. Since grasshoppers are 50 to 75 percent crude protein, they even help maintain the survival of millions of human beings in much of the world.