The Nature Writers of Texas

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

Sunday, May 28, 2006

Lizards Love Warm Weather
by Ro Wauer

Almost everyone likes lizards. Unlike closely related snakes, lizards have somehow passed the test of what yard critters are acceptable. They possess legs, unlike snakes, and so do not crawl about on their bellies; they can run about with amazing speed. Plus, lizards often seem as curious about us as we are about them. And they live in and around our homes, so finding a lizard or two is never much of a chore. Especially during the warmer days of spring, summer and fall, lizards can be commonplace.

My yard, assumedly fairly typical of most non-urban yards (I live in the Mission Valley area of Victoria County), contains five species of diurnal lizards: Carolina anole, Texas spiny lizard, six-lined racerunner, prairie lizard, and ground skink. Although when I wrote a nature note about my yard lizards in 1995, anoles where far and away the most numerous of the five, now, anoles are far less numerous and spiny lizards have increased. Racerunners, prairie lizards, and ground skinks are also reasonably common. Actually, ground skinks are the most numerous, but since they are less obvious, spending most of their time among the leaf litter, they don't get equal observation time.

Anoles are one of my favorite lizards, probably because they seem to have more personality than the others. This 3- to 4-inch lizard, sometimes known as chameleon, changes color from deep green to brown or grayish color, depending upon the substrate. Males often perch on a favorite spot and will chase other males away when they get too close. They have a habit of puffing out their throat on territory to expose a pinkish dewlap and doing a few bobs of the head or push-ups. If a rival male continues to trespass, a heated battle, with much biting, is possible. The resident male almost always is the victor, and the intruder flees.

The Texas spiny lizard is a stocky lizard with a rather scaly appearance. Most individuals are 5 to 7 inches in length, but an old-timer, that has somehow survived the predation of a number of birds, especially roadrunners and red-shouldered hawks, can reach 11 inches. This is the "rusty lizard" that prefers woodpiles, trees, and rocky places but occasionally is found in the open. Males possess a narrow light blue area, without a black border, at each side of the belly.

The six-lined racerunner is the most streamlined of my yard lizards, with a long, slender body and an extremely long tail, a total of 6 to 9 inches. The color pattern on the back consists of six light and six dark stripes, and its underparts are plain. Males sport bluish underparts. This is an active, rather bold lizard that moves in a jerky fashion when hunting, but runs away very fast when disturbed. It prefers more open, harder terrain, where it can outrun its predators.

The prairie lizard, the least common of my five species, is a 5-inch lizard with a light brown stripe, edged with lighter stripes, down its back. Males possess two long, narrow light blue patches, one at each side of the belly, bordered with black. It seems to prefer sparse ground cover.

The ground skink is less obvious, because it lives among the ground cover and humus. It is also one of the poorly marked lizards, sporting a smooth, brown to golden back, with a slightly darker stripe down the back and very short legs. Rarely more than 5 inches in length, the ground skink with slither into the humus if possible, rather than run away like most lizards. Two nighttime lizards are also resident in my yard area, the banded and Mediterranean geckos. Both are most obvious around outdoor lighting where they come to rather insects attracted to the lights.

Population changes in lizards are fascinating, and it largely is due to the population of predators. Although I still have a few anoles, the current number is only a tenth of what it was ten years ago. But the number of anole predators, including spiny lizards and red-shouldered hawks, has notably increased. My yard, in a sense, is but one tiny example of the natural changes that exist in nature worldwide.

Sunday, May 21, 2006

Birdsong Is My Favorite Part of Spring
by Ro Wauer

Each spring as the songbirds arrive or pass through our area, it is again time to remember some of their happy notes. It isn't easy to recall a couple dozen songs, especially those that haven't been heard since last spring. Some are easy, however. For me, I can always recall the songs of the eastern wood pewees, a plaintive "pee-ah-wee, pee-err;" the blue-gray gnatcatcher's lispy "spee, spee, spee;" black-and-white warbler's thin "wee-see" couplets; northern parula's buzzy "zzzzzzeeeeurp"; and the common yellowthoat's "witchy, witchy, witchy."

But that is only a start of the numerous songbirds that can usually be heard in spring. Some of the migrating songbirds sing only partial songs en route, apparently waiting until they reach their breeding grounds before delivering their full renditions. That can make it even more difficult. But nevertheless, it is still fun to try to identify, to remember, the songs from previous years. Some of the warbler songs are most difficult to separate, as they can sound very much alike. For instance, the song of the orange-crowned warbler, one of the songbirds that have overwintered in our area, can be confused with that of the Virginia's warbler, a closely related species. And the Nashville warbler, one of our most numerous spring migrant, sings a song that reminds me of that of the yellow-rumped warbler, another of our wintering species.

I have found that I often need to see them singing before I can properly remember which one is which. Right now I have several Nashville warblers in my yard. Nashvilles possess a gray head with noticeable white eye-rings, yellow throat and breast, and yellow-green upperparts. And when excited they often show a chestnut crown-patch. Their full song is delivered in two parts, the first higher and slower: "see-it see-it see-it, ti-ti-ti-ti-ti-ti."

Two additional, favorite northbound migrants to expect are the black-throated green and hooded warblers. Adult black-throated greens possess a yellow face, black throat and upper breast, yellow-green upperparts, and white wing bars. A gorgeous creature! Its full song is a husky "zee zee zee zoo zee." Hooded warblers are sexually dimorphic, in that the male looks different than its mate. Males possess a yellow face, coal black hood and neck, olive-green upperparts, and bright yellow underparts. Female are duller versions without the noticeable coal black hood and neck. Their song, though variable, can be described as a loud "weeta, weeta, wee-tee-o."

Many bird species possess a repertoire of songs, often singing different songs in order, one after the other. Our mockingbird has as many as 150 songs, while the brown thrasher can sing as many as 67 song types. And many wrens, especially the tropical wrens, often sing duets, so that one individual begins the song and its mate ends the song. And our common Carolina wren songs usually solicit songs from all the neighborhood Carolina wrens.

How many songs do birds sing is a single day? That varies with the species. Ornithologist Margaret Nice recorded 2,305 songs in a single May day for a song sparrow. She also reported that a black-throated green warbler sang 1,680 songs in seven hours. But the North American winner is the red-eyed vireo. Ornithologist Harold Mayfield recorded a Michigan red-eyed which sang 22,197 songs in a day.

Biologists tell us that birdsongs are utilized to identify the bird's territory, usually directed at other males, and to attract a mate. The song may also serve to convey a message. And it is hard not to believe that a spring migrant, en route to its breeding grounds, is not singing just because it is happy. But whatever their purpose, most listeners appreciate birdsong simply for their acoustical quality. For many of us, it would be an empty world without the sings of birds.

Sunday, May 14, 2006

The Importance of Feathers
by Ro Wauer

A recent article in Birder's World, one of the better birding magazines that I subscribe to, has an excellent article titled "What Feathers Do." Since I am constantly on the lookout for good ideas for my nature notes, this one struck me as not only a good one but very pertinent, as well. Our springtime bird migration has just about ended, and those of us who appreciate birds are still excited about what we saw.

Author Peter Stettenheim listed 23 feather functions. Although many, such as flying, shielding body parts, repelling water, and used as nesting material, are obvious, most are not so distinct. The 23 functions, listed in his order, include: conserving body heat, regulating body temperature, shielding body parts, repelling water, flying, swimming and diving, floating, snow-shoeing, tobogganing, bracing, feeling, hearing, making sounds, muffling sounds, foraging, ensuring food supply, keeping clean, aiding digestion, constructing nests, transporting water, sending olfactory signals, eluding predators, and sending visual signals.

A bird's feathers not only shields the soft body parts, but they also conserve body heat and regulate body temperature, especially important for birds in very cold and very hot climates. Feathers serve as marvelous insulation; when the feathers are erected, they allow warm air near the body to escape. And during rainy periods they are held in position to allow water to run off. This works best for those species that preen their feathers, arranging their feathers in an interlocking position as well as providing a valuable cleaning function. And water birds in particular coat their feathers when preening with oil from their uropygial gland. A few water birds such as the anhinga, however, do not have sufficient oil and must stretch out their wings to dry their feathers after fishing. Many water birds that chase prey underwater possess unique feathers that are stiff but smooth to reduce drag when moving through the water. And some are able to retain air in the downy layer for buoyancy and insulation.

Many birds of the snowy north have feathered toes that help them get around in deep snow, acting like snowshoes. And some of these same northern birds possess overlapping belly feathers that are firm and slick for sliding across snow on their bellies instead of walking.

Most owls possess feathers about their ears, a facial disc that helps their hearing. Their posterior ear coverts are movable flaps of skin that are positioned to catch sounds and determine their direction. And an owl's flight feathers and body contour feathers have a soft texture that muffle the sound of passing air and of rubbing against each other in flight. And on nocturnal owls, their outer flight feathers are fringed to lessen the sound of air turbulence.

Two of our local birds are good examples of using feathers while foraging. Reddish egrets hold their wings over their feeding sites, thus shading the water to better see prey, and mockingbirds often flick their wings out to startle prey into making a move. And what about the many bird species that use feathers to aid digestion? Grebes are good examples, as these fish-eating species swallow their own feathers, which decompose into a soft material to line their gizzards to protect it against sharp fish bones. Undigested remains are regurgitated periodically as pellets, filled with remains and feathers.

Grebes, ospreys, peregrines, and several shorebirds actually transport water to cool their nests during hot weather. These birds soak their belly feathers that are modified to increase their capacity for holding water and to withstand repeated wetting and drying.

And we all are fully aware that feathers provide significant visual signals that might be helpful during courtship or frightening off predators. Think of the red coverts of red-winged blackbirds, the white patches of mockingbirds, the head plumes of various quail, and various gorgets of hummingbirds. Without feathers birds would not be birds, and the world would be a sad place without them.

Friday, May 05, 2006

Cross Timbers Wildlife News
The Bird With The Golden Slippers
Jim Dillard, Wildlife Biologist, Texas Parks and Wildlife Department, Mineral Wells

Although this title may sound like something right out of a James Bond movie or a children's storybook character, the "bird with the golden slippers" is alive and well here in Cross Timbers Country. You won't see them at the movies or in the library, but come spring, they'll return from their wintering grounds along the Texas coast and points south to grace our north Texas lakes, ponds and wetlands.

That wasn't the case between 1880 and 1910 in the United States when the future of the snowy egret (a.k.a. bird with the golden slippers) was uncertain. Their delicate nuptial plumes (aigrettes) were worth $32 an ounce which was more that twice the value of gold back then. They were a fashion statement and used to adorn ladies hats and bonnets. As a result, plume hunters along the Atlantic and Gulf of Mexico coasts dealt a devastating blow to their population and nearly wiped them out. Not only were adult birds killed, the resulting unattended nestlings also died. Only through the efforts of early conservation organizations and enactment of laws to protect them did the slaughter stop.

The snowy egret (Egretta thula) is one of a dozen species of herons in the Family Ardeidae found in Texas. The range of this partially migratory species extends from Chili and Argentina in South America to the northern United States and southern Canada. During the fall months, northern birds move south to the coast or into Mexico, Central and South America and the West Indies. Most snowy egrets nest in coastal regions but others venture northward during the spring to inland lakes and wetlands. Here in Northcentral Texas, I've found them nesting in numerous urban rookeries along with other colonial waterbirds such as cattle egrets, great egrets, little blue herons and black-crowned night herons.

Their snow-white feathers, long slender black bill, black legs and bright yellow feet (golden slippers) make identification easy. The bare patch of skin at the base of the bill (lores) and their eyes are also yellow. During the breeding season, foot coloration changes to a more reddish orange tone. Long, graceful aigrettes on their head, back and neck can be erected and displayed to greet and flirt with prospective mates or intimidate other egrets near their territory. Snowy egrets stand about two feet tall and have three foot wingspans. Their flight pattern is direct and buoyant with steady, fast wing beats. Body weight is somewhere around 12-13 ounces. They can live up to 17 years but most don't: the record is 22 years 10 months.

For most of the year, snowy egrets are silent. During the breeding season, however, they do a considerable amount of squawking and croaking around their nesting site or when quarreling with other birds. They'll also make a rattling sound by bill nibbling; gently opening and closing their bill to greet their mate and reduce aggressive behavior.

Snowy egrets wade in shallow water areas of salt and freshwater marshes, ponds, lakes and other wetlands searching for aquatic insects, shrimp, earthworms, crayfish, snails, small fish, frogs, toads, lizards, snakes and just about anything else that wiggles. They usually move about quickly with their wings slightly elevated and use their golden slippers to stir up the bottom to flush out anything in hiding and then grab it with jabs of their bill. Other strategies are to just stand still and wait for something to swim by or stick out one foot and vibrate it to startle prey. They'll also feed in fields and pastures on grasshoppers and small rodents or drop to the water from hovering flight on their prey - whatever works. Snowy egrets are often seen feeding with other heron or egret species.

During their spectacular courtship ritual, the beautiful lacy plumes are quickly raised and lowered to gain the attention of a mate. He'll point his bill to the sky and pump his head up and down, fly circles around the nest site and fly high in the air and then suddenly drop, all to demonstrate his prowess to the opposite sex and advertise his territory.

Snowy egrets are monogamous and raise only one brood per year. They nest along with other heron and egret species in large colonies. The male selects the nest site in a tree or shrub five to ten feet tall and brings nesting materials to his mate. Together they construct a flimsy platform nest where three to five pale blue-green eggs are laid. They both incubate the eggs for 20-24 days and then begin bringing food to the young. Egg hatching is asynchronous; consequently, the last of the young to hatch usually gets little food and starves. Young that do survive clamber around on limbs near the nest site and are fed by the parents for another month or so until they're able fly off and dance with their own golden slippers in the shallows.

I've conducted surveys on many rookeries here in Cross Timbers Country over the years to estimate how many birds were nesting there and which species were present. Some of those rookeries had 20-30,000 or more birds in them on about a half acre of land. Those were days I had serious reservations about by career choice as a wildlife biologist as I waded through several inches of "you know what" and was showered from above by irate birds with "you know what." Looking up was not an option. I quickly learned to count by the thousands: one-thousand, two-thousand, three- thousand.. finished! Rookeries sites are often used for many years and the resulting accumulation of "you know what" eventually kills the trees.

The snowy egret is one of the most elegant and graceful birds you'll ever see here in Cross Timbers Country. As with other species of wildlife, water and wet places on the landscape are fundamental components of their habitat. Without it, there'll be no birds with the golden slippers to see from a Cross Timbers Country road. Until next time - I'll see you down a Cross Timbers Country road and God Bless America!