The Nature Writers of Texas

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

Sunday, April 22, 2007

Migrating Warblers, Another Spring Highlight
by Ro Wauer

Although there are lots of signs of spring all around us, none are as special as finding springtime warblers. Then they are all dressed for courtship, their plumage bares all the finery of the spring season. Those that pass through South Texas will soon be singing their unique songs from ancestral territories to the north. While of the northbound species will remain in northern Texas, such as black-and-white and prothonotary warblers and northern parulas, the majority will continue northward, some as far north as Northern Canada and Alaska.

I often find the more common migrating warblers in my yard near Mission Valley. These usually include the yellow-rumped, northern parula, Nashville, and black-and-white, probably in that order of abundance. But finding some of the others, especially those that stay awhile and especially those that decide to bathe in one of my birdbaths, is really special! And even more special is watching one of these little jewels of the songbird world that I have never before found in my yard, bathe right in front of me. That is exactly what happed last week when I suddenly discovered a cerulean warbler, a species I had never yet seen in my yard (yard bird number 178), spend a few minutes with me, Betty and son Brent, at my birdbath.

For non-birders, a cerulean warbler might be just another migratory bird passing through our area en route elsewhere. But for birders, who understand that this particular warbler has been seen less and less over the years and is being considered by many folks as endangered or threatened, seeing a cerulean warbler is indeed extra special. Ceruleans are not the most colorful of warblers, but they possess a true beauty of their own. My cerulean male was bluish, actually cerulean blue, above, brightest on the crown, two white wingbars, and with white underparts with a darker but incomplete chest band. And in the sunlight, its cerulean blue features were remarkable.

There were a few others warblers that day, probably a party of migrants that stopped briefly to feed on the available caterpillars among the oak foliage and to bathe. All of the above mentioned species were present, but that same day I also observed orange-crowned, black-throated green, and Canada warblers. All quickly passed on by.

That day of my cerulean warbler and associates was immediately following a cold front that had brought clouds and rain from the northwest and had moved into the Gulf of Mexico. That front in the Gulf probably had forced the northbound migrants, flying across the Gulf from the tip of Mexico's Yucatan Peninsula, to veer westward onto the Texas Coast to where they then followed the coastline northward. Such an event happens on a regular basis, resulting in masses of Neotropical migrants passing through South Texas rather than flying 550 miles directly across the Gulf to landings along the upper Texas Coast or Louisiana and Mississippi.

Places like High Island, north of Galveston, have a well-earned reputation for attracting birders in spring. When conditions are right, one can find hundreds of songbirds and other species among the oaks, often as many as 80 to more than 100 species. These tired Trans-Gulf migrants first rest a few minutes or longer, and then they begin to feed on the available insects, building up their body fat for the next leg of their journey.

Those of us living in South Texas can truly appreciate the spring bird migration, especially when some of the rarities, such as a cerulean warbler, put in an appearance.

Sunday, April 15, 2007

Chimney Swifts Are Welcome at My House
by Ro Wauer

A few days ago, what with our greening environment and seeing numerous migratory birds passing by, it was time to prepare my chimney for returning swifts. This was simply a matter of climbing onto the roof of my house and taking off the metal screening that I had installed last fall to help keep out the rain and cold weather. And within a few hours, as Betty and I sat inside watching television that very evening, we could hear chimney swifts already taking up residency. I had heard some swifts chipping overhead a couple days earlier, they apparently had perched elsewhere awaiting my action to let them in. I can only assume that the birds that immediately entered my chimney were the same as those that had nested there during previous years.

Although chimney swift nesting sites once were limited to dark tree trunks and similar habitats, with the advent of chimneys they soon learned to take advantage of such new sites, thus their common name. They build half-saucer like nests on the inside of chimneys, using their gelatinous saliva to cement tiny twigs together and to the wall. In one nest that John Tveten mentions in The Birds of Texas, it contained 130 twigs, each about the length and thickness of a toothpick, all laid parallel along the longer axis of the nest, forming a half-saucer about four inches across and two inches deep.

A single chimney will be utilized by only one nesting pair, although other individuals that are helpers, usually last year's young, may also be present. A clutch consists of three to five youngsters. Until they are 28 to 30 days old, they are unable to feed themselves, but soon afterward they accompany their parents on their feeding excursions. Then, several family groups may be seen feeding together. Sometimes those flying flocks may number in the hundreds.

Chimney swifts have been described as flying cigars, due to their streamlined body shape and torpedo-like flight. That flight is quite different from other birds, consisting of quick flickering wing beats and then sailing with wings held motionless. At first glance, chimney swifts might be misidentified as swallows, but swifts are not swallows at all. They are members of the same order of birds as hummingbirds, Apodiformes, a Greek word meaning without feet, which is a misnomer because they do possess feet. They are delicate yet strong enough in flight to break small twigs off trees for nesting material. Their diet consists primarily of flying insects and spiders on silken threads, and they skim water surfaces to drink.

Although these flying cigars are numerous in Texas and usually closely associated with humans, they are among our most misunderstood birds. Perhaps that is largely due to their use of the dark interiors of chimneys and other chimney-like structures for roosting and nesting. Perhaps folks that fear bats have the same fear of other species that retire to the dark side. But that is silly because chimney swifts are not only one of our most fascinating birds, but also one of the most beneficial species. They consume tons of insects and thrill us with their amazing aerial gymnastics. Especially during courtship, they fly in twos or threes, circling and diving with utter abandonment. And then they soar with their wings held in a V-shape pattern, a behavior that occurs most often with their mates.

In recent years there has been a rather significant decline in chimney swift populations throughout their range, which extends throughout Texas; they are less common in far West Texas and in the Lower Rio Grande Valley. Because of their decline, Paul and Georgean Kyle, directors of the Driftwood Wildlife Association, have established the North American Chimney Swift Nest Site Research Project in cooperation with the Texas Parks and Wildlife Department. Its purpose is to develop a better understanding of the species and to enhance their numbers. They have even developed chimney swift towers (8-20 feet deep with an external diameter of 11-20 inches) that can be constructed of wood to provide nesting sites for these misunderstood birds. Such sites are utilized by nesting as well as migrating swifts. For additional details about the project, towers, and chimney swifts in general, you may contact the Kyles at Driftwood Wildlife Association, P.O. Box 39, Driftwood, TX 78619; 512-266-2397; or DWA@concentric.net.

Sunday, April 01, 2007

Anhingas, One of Our Strangest Waterbirds
by Ro Wauer

My house is about five miles from the Guadalupe River and the scattered associated ponds. So it was a surprise to see one of these waterbirds, like a dark cross, soaring high over my yard instead of flying along the river or sitting on a snag along the waterway or a pond. It was yard bird number 177 for my growing list of bird species seen within or from my yard. That list is not growing as fast as it was a few years ago, with only the Eurasian collared-dove being added in 2005. But a soaring anhinga is fairly easy to identify because of its long neck and long, pointed bill, and long but rounded tail.

Anhingas in their more typical water environment usually are found in the water or sitting on a post or tree limb. Those found in the water often are initially misidentified as some snake-like creature because only their long neck and head may be seen, curved in a serpentine S, above the surface. It is able to cut back on the stored air so that its buoyancy declines, allowing it to sink so that its body disappears, with only its head and long, slender neck showing. Thus, one of its many names is snakebird.

More commonly, anhingas usually are found perched along the waterside, either sitting quietly with folded wings or with wings spread. The later poise usually occurs right after they have emerged from the water, and their spread-wing position allows their plumage to dry. But their spread-wing position is mostly for thermoregulation, to absorb solar energy to supplement their low metabolic heat production, after a swim. And unlike other birds that perch with spread wings, such as turkey vultures, anhingas will often sunbath facing the sun. They also are known as "water turkeys," because of their relationship to water and the unique structure of tiny cross ridges on their tail, like that of turkeys.

Still another name for the anhinga is "darter," after their characteristic feeding behavior of spearing prey underwater with their long, sharply pointed bill. They will then awkwardly fly or crawl onto a nearby perch with their prey where they then will flip the fish or other prey into the air and catch it headfirst to swallow it whole. At times, when the prey is too large to swallow whole, it will pound its prey again a perch or fly to a rocky shore and pound it into pieces. Although fish are its principal prey, anhingas are known to take a wide assortment of water creatures, including snakes, frogs, turtles, and even baby alligators.

Anhingas are members of a unique family of birds, known as Anhingadae, although this family of darters occurs worldwide. The anhinga name stems from a language of the Amazonian Indians. In North America, its breeding range extends primarily along the Gulf Coast and northward along some of the southern rivers. But there are a number of records further north, particularly after nesting. The more northern nesters migrate south in October and return in late February or March. But a few anhingas can usually be found in South Texas year-round.

Where can one expect to see one of these fascinating birds? Although they are possible along any of our slow-flowing waterways or at both small and large ponds, I have had excellent observations at cove-like sites along Coleto Creek Reservoir and at Guadalupe Delta Wildlife Management Area along US Highway 35. Good luck!