The Nature Writers of Texas

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

Sunday, July 29, 2007

Male Hummingbirds Are Early Migrants
by Ro Wauer

It seems impossible that some of the southbound fall migrant birds are already arriving in south Texas. Only a few short weeks ago we were watching the hordes of northbound migrants that were passing through our area en route to their nesting grounds to the north. And now, barely four to six weeks later, some of those same birds are heading south to their wintering grounds in Mexico and Central America. Although the majority of the neotropical migrants are still feeding young far to the north, a few, such as several of the male hummingbirds and a number of shorebirds, are already back in Texas.

It has been said, and truthfully so, that male hummingbirds are little more than brightly colored "promiscuous rakes." They have little or no home life. In spring they migrate north to ancestral breeding grounds where they establish territories, which they may defend against other hummers to their death, performing fascinating aerial displays to attract the ladies, mating whenever the opportunity occurs, and heading south as soon as all the available females are on a nest.

It is the female hummingbird that selects the nest site, builds the nest, incubates the two or three eggs, and feeds the nestlings. Male hummers are long gone halfway through the nesting season. They search out lush mountain meadows with lots of wildflowers, where they usually remain until late summer or fall. Sometimes male hummers passing through South Texas will find suitable conditions to keep them in one place for a few weeks or, rarely, into fall and even all winter.

Shorebirds share similar behavior. Many of the shorebirds that we observed along the South Texas coastline in March and April continued northward to northern Canada or Alaska. Although some shorebirds are like hummingbirds, with males departing their breeding grounds soon after mating, others are caring parents. But the great number of shorebirds that utilize the northern tundra to nest experience a short summer and extremely long days that permit a faster nesting cycle. Many nestlings are feed twenty hours a day, and many of the young are precocial (capable of a high degree of independent activity from birth): they follow their parents about, feeding on the abundant tundra insects within hours of hatching.

The long days and abundant food leads to a very swift completion of their nesting cycle. So the coastal wetlands in Texas, like a narrow part of a North American hourglass, experience great numbers of southbound shorebirds by mid-summer. And wherever masses of shorebirds are found, raptors are not far behind.

Of the hundreds of post-nesting birds that can be found in South Texas in late July and early August, my personal favorite is the rufous hummingbird. Its arrival somehow represents a very distinct change in the characters that utilize our yards. The summer resident ruby-throated, black-chinned, and the larger buff-bellied hummingbirds are less territorial and aggressive. Only the much larger buff-bellied hummer dominates a male rufous hummer. But it is the rufous hummingbird that controls the choice patches of flowers and a favorite feeder that were earlier utilized by the resident ruby-throat and black-chinned hummingbirds. Even in September, when the yard can be filled with 50 to 100 southbound ruby-throated hummers, the one or two rufous hummers that have managed to stay are dominant. Rufous males are pugnacious characters with a personality all of their own!

Sunday, July 22, 2007

Dragonflies Eat Mosquitoes by Ro Wauer

With all of our wet weather of late, we are certain to experience a greater than normal mosquito population. These little annoying insects breed in every conceivable place with standing water, and spraying/fogging of various insecticides can only keep the mosquito numbers at a reasonably low number. Also important for reducing mosquitoes are various natural predators, especially dragonflies that also increase during similar weather conditions. These dragons are voracious predators on many kinds of flying insects that they chase down in flight. Mosquitoes, ants, flies and midges all are utilized.

Two years ago we (Betty and I, along with son Brent and two Austin friends) constructed a "dragonfly pond" in our back yard. It was built more as a way to study and photograph dragonflies and damselflies than as a way to control mosquitoes. In fact, it is necessary to place "mosquito dunks" in the pond monthly to keep mosquitoes from taking advantage of that potential breeding place; it seems to have worked very well. Within only a few days after pond completion, two dragonfly species - roseate skimmer and blue dasher - put in their appearance. And by summer, a dozen additional dragonfly species began frequenting the pond and surroundings: eastern pondhawk; common green darner; variegated meadowhawk; black saddlebags; band-winged dragonlet; banded pennant; twelve-spotted, golden-winged, neon, and widow skimmers; wandering glider; and common whitetail. I managed to get photos of each.

Dragonflies, or course, are cold-blooded insects, but they are some of the earliest insects to put in an appearance during the morning hours, even before butterflies. They fly here and there over the yard, gobbling up various flying insects. But once the day warms up a little many perch around wetland areas, including my dragonfly pond. There they perch on the six sticks that I have placed around the pond for that purpose. At this writing, each stick is in use by two blue dashers, two roseate skimmers, a neon skimmer, and a band-winged dragonlet. And adjacent sticks are also in use. Our dragonfly population is at a peak.

Dragonflies often are misunderstood, and occasionally are even feared. Although some people fear all insects, as well as other critters they do not understand, dragonflies seem to be especially frightening. Maybe it is because of their large size, swift flight, and huge eyes. But actually dragonflies are fascinating insects that cannot cause people any harm at all. They do not sting and they eat lots of mosquitoes and other bothersome flies. They also are fascinating because of their amazing flights up to 60 miles per hour and ability to fly straight upward, sideways, glide, or hover. Amazing aerobatics! They beat their wings more than 30 times a second.

Dragonflies are closely related to damselflies, two insect groups within the order of odonates, of which there are approximately 5000 species worldwide and 435 in North America. The two groups are easy to separate: damselflies usually perch with their four wings pressed over their backs, while dragonflies perch with their four wings held straight out to the sides. All odonates utilize a three-part life cycle, including eggs, larva, also called naiad or nymph, and adult. Males are territorial, usually flying or perching at the edge or over water or other moist places. Their average lifespan is two to four weeks. They eventually mate with a passing female that lays her eggs in the water, on emergent plants, or in bottom sediments. Thus their relationship to my dragonfly pond, a natural attractant.

Sunday, July 15, 2007

Black-bellied Whistling-Ducks by Ro Wauer

Maybe because of the great amount of wet weather this year, but I have seen more than the usual numbers of black-bellied whistling-ducks flying about my neighborhood and elsewhere within the region of Victoria, DeWitt and Goliad counties. These relatively large ducks are easy to identify, even in flight. They are distinguished by their large white wing patches on their otherwise black wings, black belly, and a somewhat droopy, arched appearance with their neck and head held lower than the body. And they often hang their legs and feet. On a closer view, their buffy chest, gray head, and red bill are noticeable. And if that isn't sufficient, they often fly in pairs, uttering high-pitched, four-note whistle-calls, from where their name was derived.

Whistling-ducks (there are two species in South Texas, the black-bellied and the less numerous fulvous whistling-duck) utilize cavities for nesting. Tree cavities eight to thirty feet above the ground are preferred, but nest boxes placed in appropriate locations work as well. Rarely, black-bellies have been found nesting on the ground among rushes or grassy areas along lakes or reservoirs. Pairs establish a long-term bond, the female lays nine to eighteen eggs in a cavity-nest, both parents incubate the eggs, and the very precocial youngsters leave the nest within 18 to 24 hours after hatching. One by one, they jump to the ground when encouraged by the female parent. The brood then moves to the water where they remain with their parents for about six months.

After fledging, broods join with other broods, often forming large flocks. Although most of our local birds move southward for the winter months, a flock or two usually remains through the winter months, especially at preferred locations where they are able to find sufficient food. Their diet consists of a wide variety of small creatures that can be found in the water, such as snails and insects. But they also forage in cultivated fields for seeds, grains, and invertebrates. In Texas, both the black-bellied and fulvous whistling-ducks are often found feeding in flooded fields, especially in rice fields.

Black-bellied whistling-ducks reside only in South Texas and central Florida in the U.S, although they also occur in south Arizona in summer. They are a really unique duck, very different than the other members of the Anatidae Family that includes ducks, swans and geese. North American ducks can be divided into eight groupings: (1) perching ducks, such as the wood duck; (2) dabbling ducks, pond ducks that tip up to reach aquatic plants, seeds and snails, such as teal, widgeon, and pintails; (3) pochards, usually bay ducks such as canvasbacks and redheads; (4) eiders, cold ocean ducks such as eiders; (5) sea ducks, diving ducks such as scoters and goldeneyes; (6) mergansers, fish-eaters such as the mergansers; (7) stiff-tailed ducks, little ducks with a stiff tail, such as ruddy and masked ducks; and (8) the two whistling-ducks.

In winter, we can expect the majority of the perching, dabbling, pochards and stiff-tailed ducks in our ponds and reservoirs. The sea ducks are most likely only in our bays. Eiders do not occur in Texas waters. But the most likely duck to be found flying about our neighborhoods is the black-bellied whistling-duck. A marvelous addition to our South Texas birdlife!

Sunday, July 01, 2007

Nighthawks Are Common in Summer
by Ro Wauer

A reader's call telling me that he had found a nighthawk nest alongside the Victoria Electric Cooperative reminded me that nighthawks is a subject that I had not yet written a nature note about. That is in spite of the common nighthawk being numerous throughout our area each summer. They normally arrive in the Golden Crescent by April and usually head south to their wintering grounds by the end of October. Rarely, an occasional bird may stay around during the winter months. But the vast majority of those that breed in North America, throughout Texas except for the Pineywoods, spend their winter months south of the border from southern Mexico to Argentina.

Most observations of common nighthawks are of those flying overhead, either over our fields and pastures or over our towns. Although most nests are placed on the ground, they have discovered that the flat roofs of our downtown stores offer suitable sites that are less susceptible to predators. Watch for nighthawks flying over our malls, larger stores and their parking lots. And identifying nighthawks in flight is easy because they have a very distinct flight that is erratic but swift and strong. They possess long pointed wings that are crossed by a wide whitish bar, barred underparts, white throat, short bill, and a long tail. But even more obvious is their voice, that has been described as an abrupt, nasal, buzzy sound, and when they dive in courtship or over a nesting site they will often emit a loud "peent" or "boom," produced by their vibrating primaries. Another of their names is "booming" nighthawk. Although they most often perch on the ground, it is not uncommon to find them sitting on a post, on a tree branch, or even on a high wire. Oftentimes one of these birds can be approached reasonably close as they may be sleeping with closed eyes.

Our common nighthawk is also known for its distraction displays. Although when approached by a predator or human being they may show mild aggression by rapidly opening and closing their huge mouth, a more serious display involves a broken-wing behavior. This typically involves spreading and dragging of a wing or tail, while slowly fluttering away from a nest or young as if injured, essentially leading an aggressor away. Then suddenly, just when it is about to be captured, it will fly off to safety.

Our common nighthawk is a member of the nightjar, or Caprimulgiformes, family of birds. There are 77 species of nightjars worldwide, but only nine species occur in North America: lesser nighthawk of the southwestern lowlands, from the Lower Rio Grande Valley west to California; Antillean nighthawk, found only at the southern tip of Florida; common pauraque, a Mexican species found in the U.S. only in the extreme southern tip of Texas; common poorwill, a small species found in the western half of the U.S.; chuck-will's-widow, common in the southeastern U.S.; whip-poor-will, a highland species of the eastern and southwestern mountains; buff-collared nightjar, known in the U.S. only from the arid canyons of southeast Arizona and southwest New Mexico.

All the nightjars are nocturnal, although the nighthawks will cruise about their breeding grounds during the daylight hours, especially at dawn and dusk and when feeding young. Almost any flying insect, as well as smaller birds, can be listed as prey species. The majority of their prey is captured in flight. Nightjars possess great wide mouths, and usually are able to grab their prey with ease. Their unique mouth has long suggested, as early as Aristotle's time, that they suck on goats, thus giving them the erroneous name of "goatsuckers," another name that has stuck.