January 24, 2010

YELLOW-WINGED TANAGERS
One morning as I stood washing my clothes in the outside lavatory near the orchard, two dark, oriole- size birds caught my attention rushing from the shadows of one tree to another, sticking together like mutually enamored teenagers unable to get enough of one another's presence. In the shadows they looked like black birds with small, yellow patches on their wings. The yellow wing spots -- the "broad yellow flash across base of remiges," as Howell describes them -- were enough for an ID. They were Yellow-winged Tanagers, THRAUPIS ABBAS and you can see the pair perched in an Hoja Santa, Piper auritum, with the foot of one bird wrapped around the leg of another, at https://www.backyardnature.net/n/10/100124ta.jpg.

Northerners who know only the Scarlet, Summer, Hepatic and Western Tanagers might harbor the notion that tanager colors are limited to red, yellow and black. But North America's four tanager species are just the tip of the tanager iceberg, since the Tanager Subfamily, the Thraupinae, is mainly Neotropical -- mostly occuring in the American tropics. Mexico is home to about 30 species that come in lots of gaudy colors. In the world of tanagers, the Yellow-winged's lilac-blue head and lemon-olive underparts aren't particularly unusual.

Adapted to disturbed areas such as plantations, weedy forest edges and such, Yellow-winged Tanagers are fairly common in Mexico's southeastern lowlands, though the Yucatan's northern coast is too arid for them. We're nearly at their northernmost boundary here. The species is distributed south to Nicaragua.

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SKY-POINTING GRACKLES
Returning from Pisté with my backpack crammed with oranges and bananas I saw atop a thatched-roof hut three Great-tailed Grackles doing what's shown at https://www.backyardnature.net/n/10/100124gr.jpg.

The two birds on the right are males "sky pointing," a behavior also seen among the North's Common Grackles. A webpage on bird behavior describes sky pointing as a display made by a male on the approach of another male, usually resulting in one of the males departing. If I were indulge in anthropomorphic interpretation I'd say that probably in the picture we're seeing a female at the left watching two males determining who will try to claim her.

Another webpage says that sky pointing may have evolved from the birds' drinking posture. Songbirds can't swallow the way humans do so they must fill their beaks, then tilt their heads so that the water runs down their throats.

I can imagine how the drinking posture might have evolved into a ritualized display. Maybe early in grackle evolution females noticed that males who spent the most time at drinking holes were the ones who could defend themselves best from other birds wanting a drink. Thus those who spent the most time with their beaks pointing skyward were also the strongest and quickest. Eventually males learned that if they sky pointed, somehow it attracted the females. Through the millennia sky pointing drifted away from the drinking hole to the multiplicity of places where it's seen today.

You can see how the display might really serve its purpose. I watched the above birds for about five minutes and, though neither bird stopped pointing, the one on the right seemed to lose his concentration from time to time and look around. Even I could see that he wasn't as intensely engaged in the encounter as the other, and a receptive female grackle surely would have detected much more. A lady wants her fellow at least to show some enthusiasm for her.

All this is just guessing, of course. However, as an authentic animal myself with emotions inherited from ancestors that the bird and I at least very distantly hold in common, I claim some license for being able to have at least a glimmer of a notion of what is going on there.

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A WRONG-HEADED MOTH
The other day right in the middle of the trail through shadowy forest I came upon the interesting moth shown at https://www.backyardnature.net/n/10/100124eu.jpg.

One point of interest there is how the moth's patterning gives the impression that the head is at the rear end. A predator might interpret the two dark spots as compound eyes, the two hairlike appendages below the bogus eyes as antennae, the golden area as the thorax, and the spread wings as radiate from the "golden thorax." A predator laboring under these misapprehensions and trying to incapacitate his prey by striking at the head might end up doing no more than leaving a gash in the moth's back wing area, and maybe a sore tail.

Even if the predator doesn't have brains enough to be deceived like that, the bold brown lines on a white background function as "disruptive patterning," which breaks up natural lines and cause the various parts of an organism to more or less blend with a background's random clutter. This trick wasn't working at all for the individual in the picture, though, for the white triangle on the dark forest floor couldn't have been more conspicuous. I don't know why the moth was there, and saw it do nothing more than what you see in the picture.

Bea in Ontario tried in vain for three days to identify the moth on the Internet but in the end she gave up and sent the picture to Paul Opler, who oversees the Butterflies and Moths of North America website at http://www.butterfliesandmoths.org.

Paul replied: EULEPIDOTIS RECTIMARGO

Though references to this species can be found from Texas and Costa Rica, and unnamed photos of it occur here and there on the Internet, there's hardly any other information generally available. Therefore, maybe this entry will help the next person who tries to learn something about this fabulous little being. We're adding to the public domain the fact Eulepidotis rectimargo is found here in January, and that sometimes it rests very quietly and conspicuously on shadowy forest floors.

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HAIRY MAIDENHAIR
Beside one of Hacienda Chichen's pools the stone wall's interstices are luxuriantly and prettily colonized by the frilly, black-stemmed fern shown at https://www.backyardnature.net/n/10/100124mh.jpg.

Fern admirers will quickly recognize that this is a kind of maidenhair, because maidenhair fronds are three or four times compounded into small, confetti- like pinnae like those in the picture, held in place by slender, somewhat brittle, blackish stems. However, this clearly isn't any of the North's common maidenhairs, so who exactly is it?

Since the species occurs in Texas and thus is represented in the free, online Flora of North America, happily I know. It's the Hairy Maidenhair, ADIANTUM TRICHOLEPIS, of which the Flora of North America rather crisply states, "Sporulating late winter--early spring. Moist, shaded, limestone cliffs along streams and rivers, on boulders in creeks, and among rocks on steep slopes; 200--500 m; Tex.; Mexico; Central America in Guatemala, Belize."

Maindenhairs -- ferns of the genus Adiantum -- "sporulate," or produce spores, in a distinctive manner, as shown in the close-up at https://www.backyardnature.net/n/10/100124mi.jpg.

There you see three pinnules -- the smallest divisions of the compound fronds -- with curled-under, or "reflexed," margins. The reflexed margins serve as indusia, which in other species we've looked at gave the appearance of very thin, cellophane-like coverings over the sporangia. So, spores are being released from inside the pinnules' reflexed margins.

The picture also shows how Hairy Maidenhairs get the hair in their name. A similar maidenhair occurring over much of the same area and in similar habitats is hairless, or "glabrous."

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MOTHER-IN-LAW TONGUES FLOWERING
At https://www.backyardnature.net/n/10/100124sv.jpg most Northerners will recognize Mother-in-law Tongues, SANSEVIERIA THYRSIFLORA, commonly grown indoors as potted plants up North. The ones in the picture, though, are definitely doing well living outside here, and they're doing two things most of you may have never seen potted ones do: They're growing much taller than potted ones up North, and; two plants are flowering, which they seldom do up North.

Mother-in-law Tongues, native of southern Africa, down here regularly grow four and five feet tall. Often they "go wild," forming thickets as large as a house and with blades so packed together that a rabbit would have to work hard to get through them.

At https://www.backyardnature.net/n/10/100124sw.jpg you can see that Mother-in-law flowers bear six pollen- producing stamens and six perianth lobes. "Perianth" is the term used for the segments of the corolla-like part of a flower when the calyx and corolla are indistinguishable. In the picture the items looking like frankfurters split about half their lengths with the parts diverging are anthers. Anthers are the baglike part of the stamen in which pollen is produced.

A flower's female part, or pistil, consists of the stigma, style and ovary. In the picture the spherical, translucent item at the picture's extreme top, right corner is the stigma, which is where pollen grains land and germinate. The long, slender, white thing below it is the style, which is the ovary's "neck." The ovary itself, which later will mature into a fruit, lies at the bottom of the perianth tube.

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FLAMING KATYS
Another commonly potted houseplant up North planted outside here and now flowering very prettily is a red-flowered succulent going by such inspired names as Flaming Katy, Madagascar Widow's-thrill, Christmas Kalanchoe and Florist Kalanchoe. It's KALANCHOE BLOSSFELDIANA, a native of Madagascar, shown at https://www.backyardnature.net/n/10/100124kh.jpg.

Flaming Katys are members of the Stonecrop Family, the Crassulaceae. For admirers of "succulents" -- plants with fleshy parts well adapted for preserving water --the Stonecrop Family is important, for it embraces many potted plants as well as plants used in rock gardens that receive little or very intermittent watering.

An interesting feature of the Stonecrop Family is that its 25 or so genera fall neatly into two groups: Those whose stamen number equals the number of corolla lobes or petals, and those whose stamens are twice the number. Kalenchoe falls into the group with stamens twice as many as the petals, as you can see yourself at https://www.backyardnature.net/n/10/100124kj.jpg.

In that picture the stamens are small and hard to see, but all eight are visible in this broken-open, four- lobed corolla. Note the white object atop the neck of the green object in the flower's center. The green thing is the ovary, or future fruit. Its slender neck is the style, and the style is topped with a white stigma, which is where pollen germinates. At about 10 o'clock at the white stigma's edge note the tiny, pale brown item. That's the top half of one of the eight stamens' anthers, the anther being the baglike thing in which pollen is produced. In Kalanchoe stamens are attached to the corolla tube, instead of arising from beneath the ovary as in many flowers. Moreover, in this flower the eight stamens arise at two different levels on the corolla tube, most easily seen on the flower's left side.

Flaming Katys are rated as requiring temperatures of at least 50°F (10°C), though they can stand brief periods of lower temperatures, as indicated by the fact that in southernmost Florida they've been noted as escaping from cultivation.

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CANDELABRA "CACTUS" LEAVES
In little-watered rock gardens with abundant sunlight you've probably seen such spiny, much-branched succulents as the eight-ft-tall (2.5 m) one shown at https://www.backyardnature.net/n/10/100124cc.jpg.

Among the plant's several English names are Candelabra Cactus, False Cactus and Dragon Bones. Despite all the spines and the term "cactus" appearing in the name list, the plant isn't a cactus at all -- not a member of the Cactus Family. It's a member of the Spurge Family, in which we also find Castor-Bean, Cassava and Poinsettias, none of which look much at all like what's in the picture. The tiny flowers, however, are similar on them all, and flowers and fruits indicate taxonomic relationships much better than vegetative parts.

What's in the picture is EUPHORBIA LACTEA, a native of South Africa but planted worldwide. The "lactea" in its technical name refers to milky latex it leaks when injured. Break off a stem segment and lots of "milk" runs down the stem. The latex is full of diterpene esters, which means that it's mildly toxic if eaten, and burns the skin for a few minutes if it gets on you. It's a lot worse if it gets in your eyes, however.

You might wonder about this plant's leaves. Did it simply lose them during evolution the way hominoids lost their tails? The answer is shown at https://www.backyardnature.net/n/10/100124cd.jpg.

That picture shows how the Candelabra Cactus's spines occur in pairs along each stem sections' three or four angles, and how each pair of spines is associated with a tiny, green, heart-shaped leaf.

To appreciate better what you're seeing there, remember that many leaf stems, or petioles, have a pair of stipules at their bases. Usually stipules are much smaller than the leaves they subtend, and most stipules fall off when their leaf is fully developed. You can see stipules, their scars, and read about them at https://www.backyardnature.net/woodtwig.htm.

Candelabra Cactuses have switched the roles of its leaves and stipules. With them, the two stipules have enlarged and modified into two hard spines, while the leas have drastically diminished, and fall off soon after being produced. Most of the time a Candelabra Cactus bears no leaves at all, or only at the tips of its youngest stem segments. Therefore, among Candelabra Cacti, nearly all photosynthesis is accomplished by the stem, not by leaves. This situation most often evolves in plant species adapted to arid conditions, one reason being that there is less water loss, because of there being less surface area, in a roundish stem than on a similarly sized flattish leaf.

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MYSTERIOUS ROADCUT
Each week when I hike to Pisté to buy fruit, on Hwy 180 between Mérida and Cancún and about half a mile from the center of the ruins of Chichén Itzá, I pass within ten feet of the roadcut through limestone seen at https://www.backyardnature.net/n/10/100124rx.jpg.

That's a vertical section of the roadcut about six feet high. Note the weeds at the lower right for scale.

About 65 millions years ago the entire Yucatan Peninsula was covered by sea, as was much of the US Southeastern Coastal Plain. At that time, at the end of the Cretaceous Period, an object from space at least six-miles wide (10 km) crashed into the sea at a spot now located -- after the Yucatan Peninsula has risen above sea level -- a few miles off the Yucatan's northwestern coast. The crater caused by that impact, today known as the Chicxulub Crater, was about 112 miles in diameter (180 kms). The Wikipedia page describing the Chicxulub Crater is at http://en.wikipedia.org/wiki/Chicxulub_crater.

Long after the crater was formed, during the Oligocene about 25 million years ago, this part of the Yucatan Peninsula began rising, pushed upwards by forces from within the Earth. What earlier had been the carbonate- rich mud of the ocean floor, and limestone rock below it lithified from that mud, gradually rose and kept rising until today it stands above sea level, but not by much. During those millions of years ocean currents gradually buried the Chicxulub Crater beneath mud that eventually hardened into limestone rock. Today if you stand where earlier the crater was formed, you'll see no signs of a crater at all. It's all buried beneath limestone deposited since the impact 65 million years ago. At Chichén Itzá we're well outside the crater's former location, but close enough for the ocean floor here to have been very disrupted.

The mysterious thing about the roadcut is that what you see there suggests a great deal of turmoil. Sediment deposited in calm, seabed conditions is finely grained and the layering is even. The picture shows very uneven layering, some layers tilted and others not, and fragments of fractured rock appear to be embedded in what once was flowing mud. Maybe there's even a near-vertical fault cutting across the layers at the picture's right. I've seen layering like this in ancient mudflows beside volcanoes, but never in limestone areas that have been as geologically quiet as this one -- quiet since the Chicxulub Crater was formed. In fact, I can't think of anything in the Yucatan Peninsula's geological history that could have created such a story of geological turmoil as this picture suggests, except the Chicxulub Impact.

It seems that if such a wonderful exhibition of the effects of the Chicxulub Impact were known, it'd appear at websites dealing with the event -- would even be an important tourist attraction. The Chicxulub Impact, after all, is often regarded as having killed off the dinosaurs worldwide, thus enabling mammals to begin their evolutionary ascendancy, eventually making possible humanity.

Is there anyone out there who can confirm that what's in the picture is or is not evidence of the Chicxulub Impact?

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RITUALIZATION
Ever since watching the Great-tailed Grackles sky-pointing I've been thinking about similar behaviors in humans. There's plenty on the Web tracing aspects of human behavior back to their origins. If you Google the keywords "human behavior ritualization" you'll find enough to occupy you for a long time.

According to one university's webpage, Ritualization is:

A signal behavior is just behavior that sends a signal -- conveys information. When male grackles sky-point, they're sending signals to other males to stay away. When birds do such a thing we say that they're displaying but when humans do it we use different terms. Still, humans display just like other animals, and the displays are rooted in evolutionary history.

Some of our displays are "autonomic," such as when we blush from embarrassment, gasp upon being surprised, or cry from unhappiness.

Other forms of ritualized signaling require some thinking to bring about. For example, when preserved corpses of people who died in prehistoric times are found in peat bogs, frozen in the Alps, etc., their skin is often found to be tattooed. In primitive societies, tattoos were and are efficient means of sending messages about one's social affiliations and status. Tattoos must have been so important to our evolving ancestors that the urge to be tattooed has been inherited by people today. As more and more people have the liberty to "do their own thing," we see more tattoos. It's the same with body piercing.

High heels on women exaggerate hip movement, signaling ample hips, which enable women to deliver babies with fewer complications. I won't even mention theories I've read about the origin of wearing lipstick. Macho-type men with their strutting and penchant for big cars and rough talk also manifest ritualization signal behaviors.

Sky-pointing is part of what makes a grackle a grackle and really we wouldn't want grackles to stop sky- pointing, even though to our eyes they look pretty silly doing so. But, what if whenever any grackle raised his head to sky-point, someone shot the grackle's head off? Then grackles would be advised to stop sky-pointing.

What if it were realized that most human behaviors with roots in ritualization -- behaviors based on genetic predispositions for "being stylish," for glorifying group identity (elitism, racism, patriotism), for striving for more wealth and status than is needed -- were in the long term lethal, because their practice brought about the environmental effects we see manifested today?

Would we humans be any less human if we consciously abandoned our self-destructive ritualization-based behaviors?

It depends on how we define humanity. If humans are merely what our genes make us, then we'd be less human when we frustrate the dictates of our genes.

However, if we insert a spiritual element into the definition of what a human is -- if we recognize and take advantage of the Sixth Miracle of Nature, which enables us to behave in ways not dictated by our genes -- then it would be "human" to discipline ourselves enough to save Life on Earth.

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Best wishes to all Newsletter readers,

Jim