The Nature Writers of Texas

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

Thursday, December 25, 2008

Green Jays Are Back
by Ro Wauer

Green jays are back in our area of South Texas once again. But this year they are present at numerous locations, some of which they have never before been recorded. For instance at least nine individuals in three flocks were found on the Guadalupe Delta Christmas Bird Count (CBC) on Thursday, an area where they had never before been recorded. This was even though dozens of observers have combed the area as part of the annual CBC on each of the last six years. Betty and I found at least nine individuals in three separate flocks on Thursday. And closer to home, we have had at least five individuals in our yard near Mission Valley since November 7. Plus, neighbors have reported additional birds in the Mission Valley area during that same period.

The question that arises is why should these birds suddenly appear in our area? And why did they in 2006 depart after a few weeks and not reappear for two years? Three years ago on the Victoria CBC, counters first recorded a small flock off Lower Mission Valley Road. And a few days later seven individuals, maybe the same flock, appear at our Mission Oaks yard, and another small flock appeared near Mission Valley. All of these remained for about three weeks, and but then departed. Who knows what will happen to the Mission Valley birds this year.

It is not unusual for birds to wander after nesting, some for great distances. Even buff-bellied hummingbirds, one of our resident hummers that are not known to nest north of our area, can usually be found further north even into Louisiana in fall. These birds normally retreat southward by winter. This is likely to occur for our green jays, but their December-January appearance in the Golden Crescent is not part of a normal post-nesting dispersal.

One reason for some bird’s northward movement may relate to changes in essential habitat that could be related to either climate change or destruction of their habitat. It is pretty well accepted that some of the more mobile species, including many birds, can gradually move into acceptable habitats and leave habitats that are no longer acceptable behind. And that behavior of some species moving into new areas may, in a sense, be the testing of new areas. Locating new acceptable habitats eventually may prove useful if it becomes necessary to expand their range.

All of these ideas are possible for green jays. They certainly play a part in the movement of many species, especially birds and mammals. However, even less mobile species possess the ability to shift into better habitats when necessary. If their initial habitat does not meet all their needs they will either move or perish. Our current flocks of green jays are likely to return to wherever they came from by February, but they eventually may become full-time residents in our area. If so, they are more than welcome.

Thursday, December 18, 2008

Red Admiral, Our Winter Butterfly
by Ro Wauer

Fall has passed us by, and now is that time of year when those of us into butterflies must wait for several weeks before a few springtime species appear at some of our earliest blooming plants. However, there is one notable exception. Unless our days stay near freezing or below, we can expect to see a few red admirals. These lovely creatures are readily identified by their mid-size, somewhat smaller than a monarch, dark brown to black wings with a red band across each forewing and a broad reddish band on the trailing margin on each hindwing. The underside is subtly beautiful with mottled black and browns with a bit of blue evident on the forewing.

Red admirals are most closely related to the ladies, the painted, American and West Coast (rarely) ladies. They all are of the genus Vanessa, and all are immigrants to South Texas, usually appearing in late summer or fall. Most pass through our area, but a few red admirals almost always stay behind. It therefore is often thought of as our “wintertime” butterfly. However, it actually is one of the most widespread of all butterflies, ranging throughout the United States and the southern half of Canada. It even occurs throughout Mexico and most of Central America as well as the Greater Antilles.

Adult red admirals feed on fruit, sap, dung, and flower nectar. And in recent days one of my red admirals has been taking sugar water from one of my hummingbird feeders. It is large enough and with a long enough proboscis that allows it to reach the sweet liquid, apparently a substitute for nectar. They seem to be one of the most active butterflies during early mornings, even when temperatures are below 60 degree, the general temperature when we can expect most butterflies to become active.

Behavior of red admirals is similar to many of the anglewings, a general group of butterflies that, besides the ladies, includes question marks, mourning cloaks, and buckeyes. They all are fast fliers and hard to follow, but yet they suddenly will alight on a flower, leaf or substrate, walk about a second or two, than perch with folded wings. They will sit with open wings during the cooler morning hours, allowing the sun to warm their bodies. At times during cooler periods they may sit with one wing half open to reflect the warm sunshine onto their bodies.

All of the admirals are sometimes referred to as the “thistle” butterflies because, although they nectar at a wide range of flowers, they seem to have a fondness for thistles. The larval foodplants, species on which females lay eggs, include nettles, false nettles, and pellitory, all species of the nettle family. In most areas in North America they produce two broods annually, and adults and caterpillars are able to hibernate in winter. In our area, those same individuals often fly about when the temperatures permit activity.

Any day in winter when one or a few red admirals are active is a good wintertime butterfly day.

Thursday, December 11, 2008

Flocking of Birds is Commonplace in Winter
by Ro Wauer

The adage “birds of a feather flock together” is a truism that has withstood the test of time. In South Texas, huge flocks of blackbirds are commonplace during late fall and all during the winter and early spring months. The flocks are most apparent during the evening and early morning hours when they move between their roosting sites and feeding grounds.

At least six bird species make up these huge blackbird flocks, and each flock often contains two or more species. Typically, flocks of red-winged blackbirds, brown-headed cowbirds, and common and great-tailed grackles are most common. And a flock of any of these may also contain a few of the others, as well as European starlings and occasional bronzed cowbirds. At times the larger flocks appear like wisps of smoke or clouds in the distance. These birds often fly together, only inches apart in a synchronously tight flock like they are in formation, wheeling, diving, and ascending as one. They eventually will descend as one to alight in a field or pasture to feed on available seeds and insects.

Although blackbirds are best know for flocking in huge numbers, many other birds also flock, especially during the non-nesting season. Geese, sandhill cranes, cattle egrets, quail, swallows, robins, and even wild turkeys and cardinals occur in single species flocks. And wintertime mixed flocks of songbirds can also be expected. This is especially true in the Tropics. In Manu National Park in Amazonian Peru, as many as 70 species have been found in a single flock. Closer to home, mixed flocks of five to a dozen species often can be found in the company of a few full-time resident species, such as titmice and chickadees.

One can’t help but wonder what advantage flocking might be for these birds. That question has interested ornithologists for a long time, and they have discovered a multitude of answers. Some are obvious. There undoubtedly is safety in numbers; at least one member of the flock is likely to detect a predator. It gives those feeding birds in the center of the flock more time to search for food and to eat in relative safety. New food sources can be found, for the good of the whole flock, when the individual isn’t spending the majority of its time watching for predators.

Other answers are less obvious. Flocks flying in close quarters seem to fend off diving hawks, as a raptor will not dive into a solid flock for fear of injury. Flying flocks will bunch up whenever a predator appears. In the case of a mixed flock, composed of species with slightly different feeding patterns, they also are more likely to discover a greater variety of foods. Those feeding in the canopy may frighten insects into flight that are then captured by a bird feeding at a different level. And also in mixed flocks, some species tend to act as sentinels, others as guides, and others as beaters and searchers.

It seems that our wintering birds, without the requirements of territorial defense, nesting, and feeding young, actually utilize a division of labor.

Thursday, December 04, 2008

American Crows Are Commonplace, But Often are Ignored
by Ro Wauer

Almost everyone can recognize the American crow! Yet it is too often misidentified throughout much of its Texas range. The crow-like birds in South Texas and in far West Texas and the Panhandle are not our familiar American crow, but actually are Chihuahuan ravens. And the larger crow-like birds of the Hill Country and West Texas is the common raven. The American crow is actually a bird of the eastern, northern and western United States; its range skips much of the western two-thirds of Texas. Like the range of several other eastern North American songbirds, such as the tufted titmouse, Carolina wren, and blue jay, it barely extends south of the San Antonio River.

Crows are members of the Family Corvidae that also includes all the jays, magpies and Clark’s nutcracker. Corvids are some of the most intelligent of all birds, and young birds can often be tamed as pets. They also are able to solve problems and to recognize dangers that many other birds ignore. For instance, crows are reported to warn other crows of a human intruder that is carrying a shotgun. And as for problem solving, Kent Rylander wrote in “The Behavior of Texas Birds,” that crows can add or subtract: “They readily learn how to deal with novel situations (for example, taking advantage of an unconventional food source); and they respond to subtle environmental stimuli to which less intelligent birds are oblivious (for example, distinguishing an aggressive from a nonaggressive gait in a predator.”

American crows are naturally gregarious and usually will be found in flocks. Some wintertime flocks can number in the hundreds of thousands. These cooperative groups often maintain shared territories year-round. They may even fly considerable distances, like 50 miles or more, to feed. And when a predator is located, crows are well known for their mobbing behavior, including constant calling and diving at the intruder. Their best known call is an emphatic “caw caw caw,” but ornithologists have recorded at least 23 different calls. It depends on their situation, for instance, courting males sing a “rattle” song.

Crows are omnivorous and extremely opportunistic. They can take advantage of almost any opportunity to feed, utilizing seeds, grains, insects and other invertebrates, frogs, small snakes, birds and their eggs, small mammals, carrion, and even garbage. There are several instances of crows cracking hard-shelled mollusks by dropping them onto rocks from high overhead.

Like all the Corvids, crows are extremely wary and suspicious. Resting or feeding groups post sentinel birds to warn the group of any dangers. Sneaking up on a flock of crows takes special skills that few humans possess. However, by approaching ground-feeding crows indirectly and by looking away can produce some success. But just when you stop to aim a camera they will take off in the opposite direction with much consternation and vocalizations.

Although our American crow is so often taken for granted, probably because of their abundance and continual presence in the Golden Crescent, it is one of our most interesting songbirds. It is one of the first birds to call each morning, and one of the last to go to roost in the evening. It is one of our largest songbirds, yet its song is little more than a series of caw notes.