September 15, 2008

WHITE-TIPPED DOVES
Except for pudgy little ground-doves, who are almost like House Sparrows the way they forage in people's backyards and the village's open areas, the most common dove/pigeon in this area is the White-WINGED Dove. White-winged Doves often come flying over the scrub in little to large flocks, and occasionally one or two turn up right outside my back door scratching through dried manure left by the big Zebu bull they tie there overnight. Feral Pigeons also are common here.

A different dove/pigeon species regularly is glimpsed out in the scrub. This last week as I continued mapping trails I returned each day on a winding footpath through thorny forest about 20 feet high, and each day in the same spot I'd encounter one. At first he'd roly-poly amble away from me down the trail, then flutter loudly and heavily into the air, keeping low, and then vanish into heavy, shadowy undercover. About all I ever saw of him was that he was heavy and pigeonlike, bore no white wingbars like the White-winged Dove, but did have a white-tipped tail. In our area, that's all you need to see to know you have a White-TIPPED Dove, sometimes called White-fronted Dove, LEPTOTILA VERREAUXI.

The only other full-sized pigeon/dove in our area is the Red-billed Pigeon, which lacks the white-tipped tail. Farther east and south in rainier country with higher, more luxuriant vegetation, other species show up. For example, in forest near Cancún you can also look for Scaled Pigeons, White-crowned Pigeons, Caribbean Doves and Ruddy Quail-Doves. During the winter dry season North America's Mourning Doves also invade the whole peninsula. This is quite in contrast to the situation in North America where most of the continent is home to only two pigeon/dove-type birds: Mourning Doves and feral Pigeons.

One reason I give scientific names and often refer to an organism's genus is that genera and other groupings are defined by important features. In other words, if you're familiar with a genus's characteristics you automatically know a few things about each species in that genus. There's a good example of this when you read in Howell's A Guide to the Birds of Mexico and Northern Central America the description of the genus Leptotila, to which White-tipped Doves belong. Howell writes:

"These birds are common but retiring, terrestrial doves of forest and woodland. Most often seen singly or in pairs as they flush off through the understory; may be seen in the open at edges, on quiet roads, and trails."

This couldn't match my experience with them better.

*****

A DIFFERENT-LOOKING STRIPED BASILISK
The day I was assigned my current living space I was astonished to find a stall behind the casita with a working commode and shower. Probably this is the only commode in the whole community, so being given it is quite a generous act.

The first time I flushed the commode the sound of running water arose just beyond the stall's cinderblock wall and somehow I wasn't surprised when I found there, right next to my back door, a bathtub-size pit in the limestone rock where shower water and flushings permanently pool. What I'd just flushed floated atop the water and the water itself was dark with mosquito larvae, so this is the source of the cloud of mosquitoes that each night encrusts my mosquito net's walls. Flies were pretty thick, too.

In other words, it was a good place for insect-eating critters, especially red dragonflies, toads and lizards.

This week I got a good look at one of the lizards. It was a species we ran across in Chiapas, the Striped Basilisk, BASILISCUS VITTATUS, but my ten-inch-long cesspool visitor looks different from the adult male and female photographed down there, still shown online at https://www.backyardnature.net/chiapas/basilisk.htm.

At https://www.backyardnature.net/n/08/080915sb.jpg you can see that my visitor lacks the adult male's crest, yet it's not as mottled as the female. Campbell's Amphibians and Reptiles of Northern Guatemala, the Yucatán, and Belize says little about the immature Striped Basilisk's appearance, but I'm guessing that my cesspool friend is an immature male, mainly because the white line along his side is so vivid, which doesn't seem to be the case with females.

Cesspool is wet in the picture because as I was photographing him (the inset at the upper left) suddenly he spotted prey and shot off his perch into the pool. Striped Basilisks can dive under water as well as run across it. Cesspool ran across the water's surface and stationed himself on the opposite bank before I could refocus my eyes. In the picture a dead wasp lies just beyond Cesspool's head, so maybe that was the prey he'd gone after, only too late deciding he didn't want to swallow it.

*****

HELP NEEDED IDENTIFYING SNAKE
The other morning while jogging at dawn I found a snake between three and four feet long belly-up along the road. It had been shot through the head. It was so large and heavy that, with its bold blotching, in the morning twilight I thought it was a Boa Constrictor, a species fairly common in the Yucatán. However, back home and with more light it was clearly not a Boa. The shape of the head was all wrong, its pupils were circular, not "cat-eyed" like a Boa's, and the head scales were large, not tiny as a Boa's. But, what was it? Really not many species this large occur in the Yucatan, and it didn't seem to match any picture in Campbell's herp book. You can see if you recognize it at https://www.backyardnature.net/n/08/080915__.jpg.

Could it be the Blotched Hooknosed Snake, Ficimia publia? Campbell's picture of that species isn't so good, plus he speaks of an "exceptionally large male" reaching 60 cm, and what I found was easily twice that long.

*****

SOLANUM'S ANTHERS
At https://www.backyardnature.net/n/08/080915ss.jpg you can see one of the most conspicuous roadside weeds flowering here nowadays. It's a member of the huge genus Solanum, the Nightshade Genus of the Nightshade Family, the Solanaceae. I'm guessing that it's SOLANUM TRIDYNAMUM, known in Maya as Ik'om ya'ax nik.

This plant's purple flowers, about the diameter of a US silver dollar, show a curious feature common to most Solanum blossoms. Since members of the genus Solanum often are edible (Potato and now Tomato reside in it), medicinal and/or poisonous, it's a good feature to know, so you can recognize a Solanum when you meet one.

Solanum flowers generally have their petals united into shallowly bell-shaped to saucer-shaped "gamopetalous" (petals united) corollas, like the one in the picture. That's not unique to Solanums, though. What's distinctive is the turned-up yellowish thing emerging from the corolla's center. Those are anthers, which are the male stamens' baglike items that split open at maturity to release pollen. Now, here comes what's so neat about most Solanum anthers:

The vast majority of anthers of other plants split along their sides to release pollen, but most Solanum anthers open with roundish pores or holes at their tips, not long slits. A fine shot of the anther-tip pores of our Ik'om ya'ax nik is shown at https://www.backyardnature.net/n/08/080915st.jpg.

Not all Solanums possess gamopetalous corollas and anthers with pores at their tips, but if you see that combination in an unknown plant, call it a Solanum with fair confidence. One oddball Solanum is the Tomato, whose anthers open by slits along their sides.

*****

YELLOW OLEANDERS FLOWERING
In towns large and small all across the Yucatán and the rest of tropical Mexico right now one of the most eye-catching flowering plants is the Yellow Oleander, THEVETIA PERUVIANA, whose yellow, 2.5-inch-long flowers, black fruits and willow-like leaves are shown at https://www.backyardnature.net/n/08/080915tv.jpg.

YELLOW Oleander is completely different from the Oleander in my backyard back in Chiapas (see https://www.backyardnature.net/chiapas/oleander.htm) The two oleanders belong to the same family, the Dogbane Family, or Apocynaceae, but they reside in entirely different genera. Yellow Oleanders bear one leaf at each stem node (they're alternate) and the fruit is the curious fleshy drupe in the picture, while the leaves of Oleanders, genus Nerium, mostly occur in groups of three, and the fruits are slender, okra-pod-like, dry fruits, or follicles, that open along one side when releasing seeds. One feature the two oleanders share, however, is that all parts of both plants are toxic.

Yellow Oleander's thick, four-sided, black fruit is really an unusual thing. It's green when immature, then turns bright, glossy red, and finally it becomes the dull black shown in the picture. Inside resides a smooth, brown stone sometimes called a "lucky nut." Enterprising natives have been known to string lucky nuts on necklaces, and to sell them as charms for carrying in the pocket.

*****

THE YELLOW OLEANDER'S POLLINATION STRATEGY
Yellow Oleander's blossoms are large enough for us to easily see some of the flowers' basic anatomy, thus have the fun of figuring out why things are structured the way they are -- how its anatomy facilitates pollination.

Above we saw that Yellow Oleander flowers are funnel-shaped -- a narrow tube flares out above. The area where the narrow basal tube abruptly enlarges can be referred to as the "throat," and it's in the throat area where the Yellow Oleander flower manages its pollination strategy. A chart showing features of a flower's throat-area anatomy can be viewed at https://www.backyardnature.net/n/08/080915tw.jpg.

In that picture the inset at the lower right shows a kind of barrier across the top of the throat, looking down on the throat area. The larger image at the left shows the throat area in cross-section, with the female stigma and style repositioned to the right of the tube so you can see better other features of the blossom's throat. Normally the stigma and style reside in the very center of the throat and tube.

Now imagine that you're a bug drawn into the funnel- shaped flower by its sweet fragrance. When you reach the throat you encounter the star-shaped barrier at the lower right. But the sweet odor attracting you issues through the star's "arms," for those "arms" are nothing but holes congested with soft hairs pointing inward toward the holes' center. Where the hairs meet in the center of each hole there's an opening a bug might shove through, so you do.

In the cross-section at the left the star-shaped barrier you just passed through is seen as the fuzzy "roof" at the top of the image, just above the labeled anthers. Once you've passed the barrier, you need to squeeze between the barrier and the hat-shaped stigma head. If you're carrying pollen from another flower, now is when you deposit it on the stigma head, thus accomplishing the first thing the flower wants you to do.

For, your pollen grains can germinate there, send their pollen tubes down through the long style, to the ovules inside the ovary at the flower's base. Once the male sex germ transported in the pollen tube unites with the female sex germ in the ovule, then begins the process of maturing the ovule into a seed, and the ovary into a fruit, and of course that's the flower's ultimate goal.

Once you're past the broad stigma head it's easy going the rest of the way down to the nectar, especially since the hairs below the star-shaped barrier all point downward, as clearly seen in the picture.

Once you have your nectar and you're leaving the flower, once again the throat area blocks you with all those downward-pointing hairs, this time poking you in the face. However, in the image at the left, notice the glossy, hairless bulges rising below each anther and between the tufts of downward-pointing hairs. Also note how downward-pointing hairs are absent below the bulges. In other words, you can avoid the downward- pointing hairs by entering one of five hairless "doors," then mounting the hairless mound your door leads to.

At the hairless mound's top you're blocked by the bottom of the stigma and have to squeeze between the mound and the stigma bottom to get out. Notice that the stigma's bottom is notched. These notches invite you to exit in particular places. It happens that the arrangement of hairs, stigma-bottom notches and bulges all oblige you to rake past a pollen-coated anther on the way out, and naturally that's the second job the flower wants you to do -- to carry its pollen to the stigma head of another blossom, so pollination can be repeated there.

Once you've scraped past the anthers it's just a matter of going through a star-arm hole like the one you entered, then flying to the next blossom.

*****

DRAGON FRUIT, OR PITAYA
Around 2:45 PM each Monday and Friday a VW van on its last legs and with an old, dusty speaker mounted atop stops beneath a certain shadetree near my casita and a loud tape is played announcing various fruits and vegetables being sold. And aged, toothless fellow with a big belly sits up front, sometimes catnapping as his similar-look wife does business in the back surrounded by crates, buckets and bags of many kinds of produce, and with fruit-weighing scales wedged between her legs. A boy with a big grin hustles for things not within the señora's reach. About 30 oranges cost a US dollar. I buy most of my food here. We always talk awhile, and sometimes I get samples because I'm a dependable customer. Last Friday I was given a Dragon Fruit, or what they called a Pitaya, which you can see at https://www.backyardnature.net/n/08/080915pi.jpg.

This is a cactus fruit, from the genus Hylocereus, one of the Night-blooming Cereuses. The fruits are fairly soft and easy to cut with a knife, and the somewhat sweet, lightly flavored, soft-cheese-textured flesh can be scooped out with a regular spoon.

Ruth, with a house in Mérida, cuts them in halves, freezes them, then serves them as a sherbet substitute in their own shells. She describes their taste as "refreshing and palate cleansing."

The Hylocereus cactus bearing the fruit produces fleshy stems reaching up to 30 feet long and may climb onto walls and over trees with their aerial roots. Sometimes here in the Yucatán you see pitaya plantations where supports are provided for the clambering stems to grow over.

Mexicans use the name Pitaya for many kinds of cactus fruits, including small, thorn-covered ones from the wild. The fruit I was given was a particularly large one. Another variety contains red, not white, flesh.

*****

A POROPHYLLUM VARIATION
You may remember from about a year ago in Querétaro when one morning my fiend Silviano introduced me to a "weed" in the garden he was watering. Silviano called the herb Tepegua and I described it has having a "wonderfully refreshing odor, much like the fragrance of cilantro, but even sharper and more piquant, maybe like cilantro mingled with tangerine-rind or arrugula." You can see the plant and read the story at https://www.backyardnature.net/q/tepegua.htm.

Compare the picture of that herb's leaf, halfway down the page, with that of a common plant here, shown at https://www.backyardnature.net/n/08/080915po.jpg.

Leaves of the plant found here also have aromatic-oil-filled, slit-like glands and scalloped margins, the same general shape and texture, and when crushed also produce a pungent fragrance. However, the glands in Silviano's herb leaves were translucent, while ours are black. Our leaves have fewer secondary veins, and our pungent fragrance isn't particularly appealing -- it's an oily, musky, grassy odor and taste.

Still, the similarities are enough for us assume that we have two species of the same genus here. The Querétaro herb was Porophyllum ruderale. Since there's a Porophyllum listed for the Yucatan, Porophyllum punctatum, that's what I'm assuming ours is. They're members of the Composite or Sunflower Family.

I love encountering new-to-me species of genera I'm already familiar with. It's a matter of savoring a new "variation on a theme," the theme being my preexisting concept of the genus in general -- a genus being a taxonomic grouping such as "the oak genus Quercus," "the wood-warbler genus Dendroica," and such.

Most great works of music establish a theme, or dominant melody, then as the works develop the themes are revisited, each time played a little differently, usually with more and more ornamentation and daringness. Bach fugues are built almost entirely of stated and revisited themes.

That's exactly the way life has evolved on Earth. A theme was set down, which was life itself, over the eons the theme was expressed in very many ways, and today life forms are more ornamented and daring in design than ever.

Some would say that humans are almost entirely the theme of life highly ornamented and daring.

*****

EMOTIONAL DESIGN
Speaking of which, a reader writes describing me as an adherent to the concept of intelligent design, which I suppose to be the belief that a deity has constructed the Universe according to a thought-out plan. Really I don't know what the accepted definition of "intelligent design" is, but I do know that I don't want to be associated with it.

For, surely "intelligent design" is one of the most arid, uninspired and error-prone of all creative processes.

I judge the Universe-creating process to be more emotional than intellectual. It's more spiritual than intellectual, even more esthetical than intellectual. From what I can see, the Universe is more music, poetry and abstract art than anything seeming thought- through. I believe in the Six Miracles of Nature, and how can a believer in a miraculous Universe believe in "intelligent design"?

Anyway, as part of an "emotional design," I discover myself living in a world where butterflies are puffs of glad tone-color, and silvery hairs beneath leaves are friendly fragrant-strokes. The Universe is a spiritual statement I have been invited to participate in (as has every other "creation"), and I am trying to do so robustly and fully consciously.

I don't mean to denigrate intelligence. Intelligence is the gift we humans are invited to use to solve our problems. But intelligence certainly isn't the inspiration behind the creation of the Universe.

*****

Best wishes to all Newsletter subscribers,

Jim