The Nature Writers of Texas

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

Sunday, June 24, 2007

Watch Out for Copperheads
by Ro Wauer

Summertime, with its hot and humid conditions, produces just the right kind of environment that is favorable by copperheads. Anyone working outside, gardeners and others alike, should be especially watchful for these poisonous reptiles. Although the snake is most likely to occur in thickets, along streams, and in moist rocky places, the ground cover around homes in the country seems to be another favorite habitat.

Copperheads are responsible for the majority of all poisonous snakebites suffered by human beings throughout the southern states. Although this snake is relatively docile and normally will strike only when provoked, its habits can easily conflict with our own activities. However, human fatalities are rare, and serious problems seldom arise when a bite is properly treated. According to Alan Tennant in his book, Field Guide to Texas Snakes, "not a single death resulted from 308 copperhead bites over a 10-year period" in Texas. Tennant claims that copperhead poison is only half as destructive as that of a western diamondback rattlesnake.

During summer, copperheads normally spend their days hidden from view in heavy vegetation and are active only at night. During cooler weather they may be more active during the daylight hours. Prey species include a wide range of small mammals as well as lizards, frogs, and insects. Tennant points out that white-footed and harvest mice are probably their principal food species. Anoles and geckos are also readily available and are additional prey species commonly used.

Our local broad-banded copperhead, known to scientists as Agkistrodon contoris, is a rather stout snake that is rarely more than a yard long; the longest one recorded was 4 feet and 5 inches. Two additional copperheads occur in Texas: southern copperhead in the eastern portion of the state and Trans-Pecos copperhead in the Big Bend Country. Copperheads are easily identified by their rich coppery brown color and thirteen to twenty darker brown crossbands over the back. Their heads are also rather distinct. The head, where its recurved, movable fangs are located, is not only wider than the neck, a characteristic typical of all pit vipers, but also sports an elongated pinkish brown patch along and above each jaw, as well as vertically elliptical pupils.

A heat-sensor pit is located on each side of the head a little below and behind the snake's nostrils. This sensory organ acts as a heat receptor to detect prey and help the snake aim when striking at warm-blooded prey. Herpatologists Roger Conant and Joseph Collins, in their classic A Field Guide to Reptiles and Amphibians of Eastern and Central North America, warns that for freshly killed specimens, "Reflex action may last a long time, and supposedly dead pit vipers have been known to bite."

Mating occurs in early spring, soon after the snake emerges from hibernation. The female carries developing eggs inside her body all summer, and young are born (5-6 per litter) alive in late summer or early fall (August and September). However, the young copperheads, roughly 9 inches long, are born in sacs, the last relicts of egghood. In half an hour, already poisonous enough to kill small prey, they will break from their sheaths and strike out on their own.

Sunday, June 17, 2007

Green Herons Are Our Smallest Heron
by Ro Wauer

Summertime is also green heron time, for then is when these little herons can often be seen flying about, going about their business of finding food for a growing family. Most sightings of flying birds are of a rather plump body with a protruding head and bill. A closer observation of a bird perched on the ground or on a limb reveals a chunky bird with rather short greenish legs, greenish-blue back, rusty chest, black cap, and a long but heavy bill. When perched over water, it can take a waiting position that seems impossible for it to maintain its balance. If waiting or stalking doesn't work, it may actually use "bait," dropping a twig or bark into the water to lure a fish within striking distance. Green herons also are known to search for prey by raking the muddy bottom of small ponds with a backward stroke and awaiting for disturbed prey.

Their diet is varied, for they are opportunists that can utilize almost every living thing smaller than they are, and ranging from tiny fish and frogs to snails, various insects, and even earthworms. They spend considerable time searching for prey in marshy habitats, where they often are very secretive and quiet. When disturbed, however, they can explode from cover with loud squawks, like sow" or "skeow!" They may then fly to a nearby perch, flick their tail, and chastise the interloper with loud stuttering "ku-ku-kuku-kuku" notes.

Nesting can occur in small groups or as an isolated pair. Some nests are placed considerable distance from choice feeding sites. Site selection is undertaken by the male, who then perches nearby and calls repeatedly to attract a mate. Once courtship begins, according to Kent Rylander's "The Behavior of Texas Birds," he displays before his lady by stretching "his neck forward and down, audibly snaps his stout bill, and points it upward while swaying his body back and forth. He also erects his neck plumes, swells his throat, and hops from foot to foot." Once nestlings are present, both parents feed the young, but the precocial youngsters leave the nest only about two weeks after hatching and begin climbing about the adjacent branches. They are self-sufficient in about 35 days.

Green heron are common summer residents throughout the eastern two-thirds of Texas, especially common along the Gulf Coast region, but are less abundant westward. They usually arrive in our area in id- to late March and are usually gone by November. Occasionally they can be found during mild winters. Most overwinter to the south in Mexico and Central America to Panama.

They are one of our most common summer waterbirds, even occasionally flying over towns in route to and from feeding sites. They can be calm and quite or that can be one of our loudest and most obvious residents. Green herons are truly fascinating birds!

Sunday, June 10, 2007

How Many Kinds of Birds Are Nesting in Our Area? By Ro Wauer

I have just completed two breeding bird surveys in our area, driving various backcountry roads, stopping every half-mile for three minutes to record all the birds seen and heard. A route includes 50 stops. Each began at 6am, at dawn when bird song was most abundant and ended four hours later. One of my two routes started near Schroeder, north to Mission Valley, onto the Lower Mission Valley Road, and looped back to SH 264. My second route started off Stanton Road near Yoakum, southwest toward Cuero, past the prison and north across the Guadalupe River, and onward toward Cheapside.

On the two routes, I recorded a grand total of 55 bird species, 49 on the Yoakum route and 45 on the Schroeder route. What species was most abundant? Probably because their songs are so constant and easily identified, cardinals were far and away the most detected, with a total of 271 individuals. The second most abundant species was the mourning dove, with 136 individuals. And the third most abundant species, and one of our most attractive of our neotropical nesting birds, was the painted bunting, with 92 individuals. Other common species, in descending order of abundance, included American crow, northern mockingbird, Carolina chickadee, white-eyed vireo, and Carolina wren.

But some of the less abundant species are some of the most interesting, because they are either new or more abundant to these annual counts that I have been doing for several years. The one new species was the Eurasian collared-dove, a large dove that has, only in the last ten years or so, moved into all our South Texas areas in numbers. It is now breeding throughout most of Texas. Four species that have increased dramatically on my counts include the golden-fronted woodpecker, blue-gray gnatcatcher, northern parula, and summer tanager. The woodpecker is a bird of the more southern and drier habitats, like the Lower Rio Grande Valley, but has gradually been moving northward in recent years. Finding nine individuals this year suggests it is now a breeder. The three other species have been expected in preferred habitats in very small numbers in the past, but each was recorded on numerous occasions this year, probably due to the greater amount of rainfall this year that produced more suitable conditions.

For a few species, numbers were lower than normal, again maybe because of the different weather pattern this year that might have induced breeding earlier than normal. Those birds, finished with courting and less active, may have been present but not so readily detected. Lower than normal numbers of the black-bellied whistling-duck, wild turkey, red-shouldered hawk, crested caracara, barred owl, chimney swift, and purple martin were recorded.

Additional bird species recorded on my two counts, not mentioned above, included northern bobwhite; great blue and green herons; great and cattle egrets; blue-winged teal; black and turkey vultures; white-tailed kite; killdeer; Inca dove; common ground-dove; yellow-billed cuckoo; roadrunner; red-bellied and ladder-backed woodpeckers; great-crested, brown-crested and scissor-tailed flycatchers; Couch's kingbird; blue jay; cliff and barn swallows; tufted titmouse; Bewick's wren; eastern bluebird; European starling; lark sparrow; red-winged blackbird; eastern meadowlark; brown-headed cowbird; and house sparrow.

Breeding Bird Surveys are part of a nation-wide effort to document species during the breeding season throughout North America. Started in 1966, the surveys form a significant database that provides important information about populations changes over time. Those in South Texas are especially worthwhile because they are documenting the changes that are taking place as a result of climate change.