The Nature Writers of Texas

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

Sunday, October 26, 2003

How many Animal Species exist Worldwide?
Ro Wauer, October 26, 2003, The Victoria Advocate, © 2003

There is an old saying that "little fish have bigger fish that feed on them and bite 'em, and big fish have still bigger fish, and so, ad infinitum." That quote can easily refer to the animal kingdom with its amazing diversity and huge numbers. It is like a great pyramid of life, with the greatest numbers of animal species at the bottom, supporting lesser numbers toward the top. Vertebrates sit at the top, with mammals, including we humans, near the summit.

But have you ever wondered about the total numbers of animal species that exist on planet Earth? Although more than a million have been described, the actual number may be closer to 10 million. Described insects alone make up the largest number at about 751,000 species, but Smithsonian Institution entomologist Terry Erwin estimates there may be 30 million species of tropical insects alone, a far cry from our current understanding. A fascinating indication of how little we know about our world. Edward Theriot, director of the Texas Memorial Museum and president of the Association of Systematics Collections, is quoted as saying: "We don't even know enough to tell you what we don't know."

After insects, the next most numerous kinds of animals are the noninsect arthropods at about 123,400 species. These are the crustaceans such as spiders, mites, and scorpions (about 35,000), centipedes (about 2,000), millipedes (about 7,000), as well as crabs, lobsters, crayfish, and shrimp (about 30,000). Next in numbers are the mollusks at about 110,000 species. These include snails, whelks and slugs that comprise 80,000; clams, oysters, mussels and scallops that account for about 15,000, chitons about 700, octopuses and squids about 400, and tooth or tusk shells about 350.

The protozoa, tiny single-celled organisms such as amoebas, are next with about 30,800; fishes and lower chordates with about 28,800; and earthworms with about 12,000 species. The fishes include about 23,000 species, divided into three groups: lampreys and hagfish; sharks, rays, and skates; and the bony fish, such as sturgeon, trout, perch, and other modern forms. Birds are next in numbers with about 9,000 species worldwide, followed by reptiles, including snakes, lizards, turtles and crocs, with about 6,300 species.

Echinoderms are next with about 6,100 species. These are the starfish, brittle stars, sea urchins, sea dollars, sea cucumbers, and such, all have tube feet and occur only in marine environments. They are followed by the mammals with about 4,500 species, and lastly are the amphibians, the frogs, toads and salamanders, with about 4,200 species.

Vertebrates, the mammals, birds, reptiles, amphibians, and fish, those species with a backbone, number only about 44,000 species in total. They are but a tiny part of the animal kingdom. Yet we mammalian humans apparently are the only ones that seem to care about numbers and categories; we constantly strive to find more. New species of whales, monkeys, deer, and birds, as well as far more forms of invertebrates, have been discovered in recent years. In future years, it is not unimaginable that the number of animal species on Earth could increase by a factor of 10 or more.

Yet, all the while, human activities throughout our planet are seriously affecting our animals. Pollution of all types is causing noticeably declines in amphibians, a group of animals that well may be our "canary in the cage." Land clearing for developments, grazing, and agriculture, also is leading to dreadful losses and declines. We know so little about the abundant species being lost. Their value for medicines, as one example, will never be known.

Sunday, October 19, 2003

October is Butterfly Month in South Texas
Ro Wauer, October 19, 2003, The Victoria Advocate, © 2003

OCTOBER is when the majority of the approximately 150 butterfly species that have been recorded in the Central Gulf Coast region can be expected. Many may remain active until the first really cold winter days arrive. Increasing numbers begin in late summer and fall when butterflies from more tropical areas stray northward. September and October is when southbound migrants, such as monarchs, red admirals, and painted ladies join the throngs of full-time residents and strays. October, therefore, is when butterfly enthusiasts in our area can find 45 to 55 species during a single day.

Many of the tropical strays are striking in appearance! Zebra and Julia heliconians, white peacocks, soldiers, and sickle-winged skippers cannot help but attract attention. Yet many of our full-time residents are just as spectacular. Giant swallowtails, great purple hairstreaks, gulf fritillaries, common buckeyes, queens, and white-striped longtails can easily match the fall strays. Although the majority of our butterfly species can be expected almost anywhere, a few, such as the palamedes swallowtail, great southern white, dark tropical buckeye, and salt marsh and obscure skippers, normally are found only along the coast. A visit to Aransas National Wildlife Refuge is the best bet for finding spectacular palamedes swallowtails nectaring among the many wildflowers.

The hobby of butterfly watching is a relatively recent phenomenon. It is about where the hobby of birding was when the first really good bird field guides became available in the 1960s. Only during the last few years have some excellent butterfly field guides appeared, making it possible to identify butterflies in the field without collecting specimens. And new close-focusing binoculars have added measurably to field identification. In addition, numerous towns, parks and refuges, as well as private citizens, have installed butterfly gardens, a great way to attract butterflies for easier observations. Examples of recently developed gardens include Victoria's Master Gardener's Demonstration Garden near the airport, Bay City's Matagorda County Birding Nature Center along SH 35, and Rockport's Green Acres Demonstration Garden in downtown Rockport. These new gardens not only attract butterflies but butterfly enthusiasts as well. And with the publication of my "Site Guide to Texas Butterflies" (Texas A&M Univ. Press) next year, that will include these three sites along with a grand total of 75 butterfly finding sites throughout the state, butterflying undoubtedly will come into its own, an important part of the Texas ecotourism industry.

Texas is the number one butterfly-state with more than 425 species, almost 100 more than second place Arizona. About 725 species have been recorded in North America, north of the Mexican border. Butterfly enthusiasts travel to Texas just to find butterflies, and their numbers increase substantially every year. The Mission, Texas, Chamber of Commerce has already recognized this potential and this year's "Texas Butterfly Festival" (www.texasbutterfly.com), also in October, is in its eighth year. The Lower Rio Grande Valley, with 265 species, is recognized for the greatest number of species in North America. Lepidopterists, scientists who study butterflies and moths, claim that 15,000 to 20,000 butterflies occur worldwide.

Another reason for the increased interest in butterflies is their wonderful diversity. Within our own neighborhoods can be found both the largest (giant swallowtail) as well as the smallest (western pygmy-blue) of North American butterflies. We also can find species that congregate at tree sap or fruit, such as the tawny emperor, question mark, and goatweed leafwing. Or we can find a yellow butterfly with a perfect dogface marking, the southern dogface. Flying is shaded areas may be a Texan crescent, our only butterfly named for the state. And when weather conditions are just right, American snouts, a small butterfly with a long snout, can be so numerous that they literally can darken the sky in flight.

Butterfly gardens continue to spring up all across the state. With the right plantings, even private gardens can become a butterfly magnet. One day last October, I recorded a grand total of 43 species in my own yard near Mission Valley. The dozen most common species that day included cloudless and large orange sulphurs, dusky-blue groundstreak, gulf fritillary, monarch, queen, coyote cloudywing, tropical checkered-skipper, and sickle-winged, clouded, dun, and ocola skippers. Gardens also attract strays or rare species that seem to appear out of nowhere. A white angled-sulphur, banded hairstreak, Cassius blue, gray cracker, Zilpa longtail, and white-patched skipper, species not previously known for our area, have taken advantage of flowering handouts in my garden.

Butterfly identification can be fairly easy with the right tools: a good field guide, a local checklist, and close-focusing binoculars. Size is important in butterfly identification, but wing pattern is even more important. Any species can vary in size by as much as 40 percent, depending on the nutrients available to the caterpillar, the butterfly's larval stage. Butterfly wings often possess shiny bright lines, amazing eyespots and even tails, useful for fooling predators, as well as spectacular colors. Behavior can be another good clue to butterfly identification, whether it is soaring about like swallowtails or monarchs, flapping and gliding like buckeyes or common mestras, flying swiftly in circles like blues or hairstreaks, or "skipping" about like skippers. Good field guides contain these insights.

There are several good reasons that butterfly watching is gaining so much momentum. It is not only because they are beautiful and fascinating creatures, but, more than any other wildlife, they can easily be attracted to our yard or any other outdoor location desired. And because many butterflies roam widely about, garden visitors in the afternoons can be different than those in the mornings. For many of us, butterflies represent the very best of the natural world: beauty, purity, and insight into the great outdoors.

A recent butterfly garden brochure, written by Derek Muschalek of Yorktown and I, contains all the best butterfly plants for our region. Our brochure - "Central Gulf Coast Area" butterfly garden plants - is available on line at www.naba.org.

The author's 12 top butterfly (nectaring) garden plants include (1) crucita (Eupatorium odoratum), (2) Mexican heather (Cuphea hyssopifolia), (3) "New Gold" lantana (Lantana sp.), (4) weeping lantana (L. montevidensis), (5) Gregg's eupatorium (Eupatorium greggii), (6) pentas (Penta spp.), (7) butterfly bush (Buddleia lindenyi), (8) sky-flower (Duranta erecta), (9) cowpen daisy (Verbesina enceloides), (10) skeleton golden-eye (Viguiera stenoloba), (11) butterfly bush (Buddleia davidii), and (12) Texas kidneywood (Eysenhardtia texana).

Suggested Field Guides
Butterflies of North America (Kaufman Focus Guides) by Jim Brock and Kenn Kaufman, 2002. Houghton-Mifflin Co., Boston, MS.
Eastern Butterflies (Peterson Field Guides) by Paul Opler and Vichai Malikul. 1992. Houghton-Mifflin Co., Boston, MS.
Butterflies Through Binoculars, The East by Jeffrey Glassberg. 1999. Oxford Univ. Press, NY.

Sunday, October 12, 2003

Migrating Hawks Still Moving through South Texas
Ro Wauer, October 12, 2003, The Victoria Advocate, © 2003

The major thrust of the hawk migration has pretty well passed through the Central Gulf Coast area by now, but small numbers of species can still be seen. And raptors are still being tallied at two key "hawk-watch" sites along the Texas Gulf Coast. Reports from the Smith Point site near Anahuac National Wildlife Refuge, north of us, and at Hazel Bazemore County Park, to the south, reveal some fascinating numbers as of October 1. Smith Point hawk-watchers have since August 15, reported a grand total of 12,579 individuals of 17 species, and Hazel Bazemore hawk-watchers have tallied 690,387 individuals of 24 species.

Smith Point totals include 31 ospreys, 97 swallow-tailed kites, 6 white-tailed kites, 3,675 Mississippi kites, 51 northern harriers, 354 sharp-shinned hawks, 246 Cooper's hawks, 23 red-shouldered hawks, 7,766 broad-winged hawks, 51 Swainson's hawks, 10 red-tailed hawks, 5 white-tailed hawks, 1 bald eagle, 5 crested caracaras, 166 American kestrels, 43 merlins, and 39 peregrine falcons; additional numbers represent unidentified species.

Hazel Bazemore totals include 154 ospreys, 21 swallow-tailed kites, 9,735 Mississippi kites, 1 hook-billed kites, 34 northern harriers, 367 sharp-shinned hawks, 460 Cooper's hawks, 17 red-shouldered hawks, 678,204 broad-winged hawks, 281 Swainson's hawks, 92 red-tailed hawks, 2 ferriginous hawks, 3 white-tailed hawks, 6 zone-tailed hawks, 3 Harris's hawks, 1 bald eagle, 467 American kestrels, 48 merlins, 125 peregrine falcons, 11 prairie falcons, 1 aplomado falcon, and 15 crested caracaras.

The high number of broad-winged hawks for both sites, especially for Hazel Bazemore, is truly amazing. This hawk nests throughout the eastern half of the United States, and an estimated 95 percent of the population migrates southward along the Texas central Gulf Coast. The area is a like a huge hourglass with our area representing the constructed center. They overwinter in South America.

Broad-winged hawks are fairly small hawks, built very much like our common red-tailed hawk, but with a banded rather than an all reddish tail. On peak days in late September, up to 100,000 hawks, principally broad-wings, have been seen in a continuous flight that extends over 40 miles long.

One of the most spectacular parts of the hawk migration is watching numbers of broad-wings during the morning hours when they begin to leave their overnight roosts. Usually around 8:30am, they slowly begin to lift off, circling low and gradually ascending higher and higher, eventually to a point where they are out of sight. But the circling of hundreds or thousands of hawks is a sight to behold. The Hazel Bazemore site, because of its location on a hill overlooking a wooded riparian area utilized by roosting broad-wings, offers marvelous opportunities for just such experiences.

Hawk migration occurs in many parts of the world, and organized hawk-watches at a few key sites have provided some amazing statistics. The best known historic sites include Pennsylvania's Hawk Mountain and New Jersey's Cape May Point. But in recent years, Texas sites have produced even greater numbers, and a site in Veracruz, Mexico, has produced even higher numbers. But the single most productive North American site is Hazel Bazemore, where up to 100,000 individual hawks can pass over in a single day.
Hazel Bazemore hawk-watchers welcome visitors. Located west of Corpus Christi, the county park is located off SH 624, only a couple miles west of US 77 at Calallen. A great place to enjoy wildlife!

Sunday, October 05, 2003

Winter Birds are Arriving
Ro Wauer, October 5, 2003, The Victoria Advocate, © 2003

With the demise of summer, many of our wintertime birds are arriving on territories that they will utilize until spring. Although many of the bird species, currently in our neighborhoods that eventually will remain over-winter, are only migrants passing through. But there are at least three species that already have taken up territories that they will frequent all winter. For me, these three species - American kestrel, belted kingfisher, and loggerhead shrike - are good indicators of the coming winter season.

All three of these birds generally are well known, and they can normally be found in numbers throughout South Texas all winter. And American kestrel and loggerhead shrike may even nest in our area in small numbers. But finding them on the same wintering grounds that they use year after year is a pretty good indication that they are back. In the case of the kestrel, the vast majority of the early birds are females. It is the larger female American kestrel that typically arrives on its wintering grounds ahead of the male. Its early arrival allows it to select preferred habitats, so when the smaller males arrive they must take secondary locations. They sometimes attempt to displace the larger female, but rarely succeed. She utilizes open fields with perches from where she can watch for prey. He often frequents grassy areas, such as road rights of ways; we therefore find more males on roadside utility lines. He is the brighter of the two. Male kestrels are gorgeous birds with a rusty back and tail and slate blue wings, while the female is less colorful and lacking the bluish wings. Both possess a white face with two black streaks. And both also are able to hover in mid-air while searching for prey. They also kite against the wind, flying at an appropriate speed facing the wind so they can stay in place.

Belted kingfishers rarely are found away from water areas where they hunt for prey such as frogs, fish, small snakes, and even insects when necessary. They, too, perch on utility lines and poles, when those sites offer views of water hunting grounds. When a prey is found, they quickly dive onto their prey, sometimes becoming totally submerged before "flying" out with their catch clutched tightly in their heavy bill. In cases when a large prey species has been speared, they are able to flip it into the air and catch it so it can be swallowed headfirst. Extremely large prey may stick out of the bill until it is slowly digested and swallowed. Belted kingfishers are mostly blue and white birds, although the female also has a rusty bellyband. And they also have a loud, dry rattle call that can hardly be ignored from up close.

The third bird considered an indicator of winter is the loggerhead shrike. It is only half the size of a kestrel or kingfisher, but it is a very tough character. One look at its rather short, stout appearance is likely to convince anyone that it is one serious bird. It is one of the very few songbirds that is able to capture prey as large or even larger than itself. Although less than eight inches in length, it sometimes preys on larger mockingbirds. It is also known as "butcher-bird," because of its predator habits. Males actually impale their catch on thorns or barbed wire, their method of storing prey and also a way of showing their prowess to female shrikes. And their call is also distinct, a harsh, high-pitched rattle.

There are many other birds that will be appearing very soon in our neighborhoods that will remain for the winter, but for me at least, none are better indicators of the coming winter than the American kestrel, belted kingfisher, and loggerhead shrike. Each in its own way offers a welcome diversion from the abundant migrants passing us by.