March 17, 2008
Last Thursday a cool front passed through (still got into the lower 90s) so I wondered whether a birding walk after such a front might yield more migrant warblers than usual. That's sometimes the case during spring migration up North.
In a certain acacia at one time I saw a Magnolia Warbler, a Black-throated Green Warbler, a Nashville Warbler and a Black-and-white Warbler, all silent except for the Magnolia, who was chipping but not singing. In the bushes nearby a Tennessee Warbler was indeed singing, not very robustly, but unmistakably. A few minutes later as I passed a shadowy thicket up popped a silent Yellow-throated Chat, the first I've seen here. Earlier in the same place I'd spotted a Kentucky Warbler, skulking and not making a peep.
All these species overwinter here but until now I've not seen them so conspicuously and vigorously foraging, even at 10 AM which is when I saw them. Usually by that late in the morning the overwinterers are quieting down as the heat builds and builds.
Definitely that day our overwintering warblers were friskier and eating more than usual, getting their bodies fat and strong in preparation for the flight they'll be embarking on pretty soon. Curiously, the next day when the usual heat and humidity returned I walked the same route but didn't see a single species mentioned above, though an overwintering MacGillivray's Warbler was present.
On the previous day had I witnessed a mixed-species wave of warblers passing through, or where they all there on the second day as well, just laying low because of the heat?
Whatever the case, you folks up north should be getting your field guides and binoculars ready because warblers are definitely stirring down here, at least sometimes! And that Tropical Mockingbird I've mentioned now sings lustily well into the late-morning heat. The first cicadas also have begun their droaning.
Years ago I lost count of the number of times during the winter I'd bussed south from the US deep into Mexico. During all those trips my first bus-window sighting of a particular tree species always gladdened my heart, for it meant that I'd finally made it back to the tropics.
The tropic-announcing trees were members of the genus CECROPIA, which used to be placed in the Fig Family but new gene-sequencing studies fit it into the Nettle Family. Cecropias just don't grow where during any part of the year it gets very chilly or dry. They need year-round water and heat.
In certain relatively sheltered covess and along streams here we have Cecropias. They're absent from exposed slopes, which are too dry. Probably before the valley floor was converted to sugarcane production Cecropias were common there. You can see a Cecropia's characteristic umbrella-like leaves and gangly, thick, soft-wooded, hollow, wide-spreading branches at http://www.backyardnature.net/n/08/080317gu.jpg.
Two species of Cecropia are listed in Breedlove's Flora of Chiapas, C. peltata and C. obtusifolia. Ours is C. peltata. I think it must be too arid here for obtusifolia, which is common across the mountains on the more humid Gulf side.
Our Cecropia peltata is such a vigorous species that it's become an invasive weed in Hawaii, French Polynesia, West Africa and Malaysia, where it invades disturbed areas, lava flows, and forest gaps. It's even nominated for the Global Invasive Species Database's World's Worst Invaders List.
Once I asked a relatively big-time medicinal herb dealer at the vast Merced Market in Mexico City what he regarded as his most important medicinal plant. Guarumo, he replied in an instant, and Guarumos are Cecropias. Las Plantas Medicinales de México reports that Guarumo is useful against obesity, asthma, liver ailments and diabetes. The trunk's skin contains cecropina, considered to be a powerful heart tonic and diuretic. The plant's greatest use, however, seems to be against "hidropesía," which I don't know how to translate.
Another conspicuous and easy-to-identify group of plants in relatively moist habitats here are members of the genus Piper. Pipers are slender bushes or small trees of the Piper Family, in which the popular house-plants known as Peperomias are found. Pipers are easy to recognize because of their slender spikes of very tiny, crammed-together, much-reduced flowers, as demonstrated by our most common Piper, PIPER AURITUM, at http://www.backyardnature.net/n/08/080317pb.jpg.
Piper auritum's crushed leaves emit a pungent, sarsaparilla-like odor. When I worked at the Missouri Botanical Garden in St. Louis back in the 1970s I studied Panamanian Pipers. My work cubical used to be the most fragrant of all at the institution, and no Piper was more spicy-smelling than Piper auritum. Here people often cook their tamales wrapped in Piper auritum's leaves so that the leaves' spicy taste is imparted to the tamales. Piper auritum is often called Hoja Santa here, or "Blessed Leaf."
When Piper auritum's small, greenish spikes of immature flowers first emerge, often they hang down, as in the picture. When flowers in the spikes are mature, the much larger, vividly white spikes are held erect. When the spikes bear maturing fruits, they are once again bent downward. This is another instance of a plant causing its flowers needing to be pollinated to be more attention-getting to visiting pollinators than its immature or already-pollinated flowers.
At http://www.backyardnature.net/n/08/080317pa.jpg you can see another common species here, PIPER MARGINATUM, if my memory serves me. Piper marginatum is one of few Piper species with leaves with several pronounced veins radiating from the petiole's point of attachment at the blade's bottom instead of having a single midrib extending up the leaf, with several secondary veins branching off it.
The most famous of all Pipers is Piper nigrum from tropical Asia. That's the plant from which black pepper is made. Peppercorns are dried Piper nigrum fruits. "White pepper" is made from dried Piper nigrum fruits from which the ovary walls have been removed. Our Pipers don't produce fruits big enough to fool with.
On Mondays when I visit the cyber in Pujiltik, before reaching the paved road where I can catch a minibus to town, I hike about half an hour through sugarcane fields. In most places this amounts to passing down an alley with impenetrable sugarcane walls 12 to 15 feet high. In other places you can see scenes such as shown at http://www.backyardnature.net/n/08/080317sc.jpg.
In that view sugarcane recently has been cut and now the field is being irrigated while new, foot-tall sugarcane shoots are emerging from the plant's perennial stem-bases. The shoots grow tall, when they're mature and most of the lower leaves are dried out and light brown, the field undergoes a spectacular controlled burn that cinderizes the dead leaves and makes the sugar in the thick stem easier to remove. The stalks are then cut and trucked to the big sugar mill in Pujiltik, and back in the fields the process begins all over again.
Many streams traverseh our area, descending from the rainier Chiapas highlands immediately to our north. Over the centuries a complex network of irrigation canals has been developed, one consequence of which is that natural rivers are pretty much dry at this time of year. The canal in the picture runs atop a low ridge, enabling water to escape on both sides in a more or less haphazard but fairly effective manner. Note the concrete gates with their plywood barriers fitting into grooves. Once the field before us is watered the plywood barrier can be shifted to the farthest gates and if the gate as the left is left open water will run toward the left.
I'm told that you have to renew the perennially sprouting sugarcane stems after five to ten years. The exact time seems to be a matter of debate, some saying that for maximum sugar-producing efficiency you should renew every five years, others swearing that you're wasting money if you replant sooner than every eight to ten years.
I've read that no other crop converts air and water to carbohydrate as efficiently and prodigiously as sugarcane. This places sugarcane at the heart of a great debate currently being conducted with regard to biofuel production. On the one hand, Brazil being the largest sugarcane producer, it's feared that that country will convert its Amazon rainforest, "Earth's lungs," to sugarcane. On the other hand, many, especially here in Mexico, say that with sugarcane so much more productive, we shouldn't be converting corn and other edible grain to biofuel because people need to eat that grain.
I've heard few suggestions that people need to travel less and, especially in North America, walk and bike more, and use mass transit, so I'll voice that opinion here. And to be even more provocative I'll say that we need to reduce our appetites and numbers drastically.
Sugarcane is a grass, SACCHARUM OFFICINARUM. The last I heard it was considered to be a long-cultivated horticultural form of a wild grass species not yet identified, probably to be found in Asia.
Hardpans are soil zones that, relative to soil above and below them, are so hard and impermeable that air, water and plant roots can't easily pass through them. After rains soil on level fields with hardpans often gets waterlogged. Air can't circulate properly in soil with hardpans and this can lead to severely stunted crops, even if the soil contains all the nutrients the crop needs. In nature vegetation atop hardpans often is highly specialized for dealing with extreme soil conditions.
One way hardpans form is when farmers plow at the same depth year after year. Above the hardpan the soil is kept loose but immediately below plow-blade level heavy farm equipment keeps compacting the soil year after year.
Other hardpans form from chemical action, especially in irrigated areas such as ours. The other day as I walked along one of our canals I saw a canal wall that almost explained the whole process by itself. See it at http://www.backyardnature.net/n/08/080317hp.jpg.
In that picture young corn grows at the top and water runs at the bottom. In between you see dark soil with a broad, white band running horizontally across it. The whiteness is carbonate left behind when carbonate-rich water evaporated.
Below the white band the soil is so moist that the carbonate remains in solution and doesn't concentrate. Above the band the soil is flushed frequently enough by rain and artificial irrigation that carbonate levels remain low. I've already mentioned how our carbonate-rich mud clods harden into genuine rocks when they dry out. That white band extending at the same depth all across the field creates a classic hardpan. I expect that as years pass it'll get harder and harder, unless they change their irrigation practices or start plowing deeply enough to break it up.
But irrigation seems here to stay, and folks around here don't have such big machinery.
One reason large machinery is absent is that much of a crop's income goes to buying chemicals to keep fields as weedless and green looking as is shown in the picture. Most roadside signs around here promote agricultural pesticides. Two names I recognize are Paraquot and 2,4-D.
Do you have any idea what's going on in the picture at http://www.backyardnature.net/n/08/080317bc.jpg?
That's a birdseye view down a cone-shaped, expanding banana leaf before its leaf unrolls. I always check such natural cups because sometimes you find interesting frogs and such inside.
When the blades of some kinds of plants emerge from their buds they're folded like a sheet of paper doubled across its middle -- they're "conduplicate," it's said. Other leaves emerge with rolled-up or coiled blades like the banana leaf in the picture.
When you're trying to identify plants this is a feature worth noting. Some plant families produce conduplicate leaves, others coiled. In fact, coiled leaves can be rolled inward, or toward the upper surface, in which case they are said to be "involute," or else they can be rolled backward to that, and are consequently "revolute." Anyway...
At http://www.backyardnature.net/n/08/080317bd.jpg you can see the actual sprout whose interior is shown above, emerging from the side of a machete-truncated banana plant stem. The concentric rings are not annual rings, nor are they really concentric, for each "ring" only continues part of the way around the stem. Each "ring" is a cross-section of a leaf petiole. The stem consists of several petioles overlapping one another.
All this makes sense when you realize that what we usually think of as the "banana tree" is actually just an ephemeral shoot arising from an underground rhizome. Once the shoot flowers and fruits it dies back and then the rhizome produces another shoot. Remember that a rhizome is an underground stem. In a sense, the "real banana plant" remains unseen, growing subterraneanly.
Commenting on last week's water-droplet-on-Elephant-Ears essay, Al in the Tennessee Smokies writes that a whole new world has opened up to him now that he's begun using his digital camera to make near-microscopic close-ups of what he finds on his walks, especially lichens.
"I feel that digital photography empowers us to appreciate the innermost workings of plants more than we'd ever have dreamed possible," he writes. "Seeing all of those 'hidden' details ignites our curiosity in ways a simple overall view never could, eh?"
Al has stumbled onto something important here, and you can as well. You'll be amazed at what you start seeing and feeling once you begin making close-ups of plants and animals you may be around every day.
I produce a special page on digital photography at http://www.backyardnature.net/digi-cam.htm.
You can do mind-boggling things with your high- resolution digital images using a good graphics program such as PhotoShop or CorelDraw. Take a look at http://www.backyardnature.net/graphix.htm.
A number of free websites invite you to upload your images to share with others, without having to know anything very technical. To find such sites, just use a search engine and the keywords "free image uploads."
You might enjoy Al's hiking journals and musings from eastern Tennessee. On his hike of March 3rd the wildflowers he reported flowering were Virginia Spring Beauties and Star Chickweed. His page is here.
Every six months I must acquire a new tourist card in order to remain in Mexico. The last few times I renewed on the Texas/Mexico border but now I'm much closer to Guatemala than the US. Therefore, last Monday morning I took three microbuses and a taxi to the Guatemala border, taking two and a half hours.
On the Texas border if you have a US passport the Mexican customs agent just gives you your card. Down here, at customs in the Mexican border town of Ciudad Cuauhtémoc, I was told I couldn't have a tourist card until I got an exit stamp in my passport from Guatemala. So I entered Guatemala in order to leave. The Guatemalan officials told me I couldn't have an exit stamp until I'd been in the country for three days.
However, for 500 pesos, about US $50, they could arrange something special. When I indicated that I'd just camp nearby for three days I was shown that day's newspaper full of gory photos of bloody bodies from the previous day's shootings and stabbings, to make the point that getting to someplace safe and staying for three days would make a $50 investment seem like a good deal.
One printable name for bribes down here is "la mordida," which means "the bite."
With a new six-month tourist-card I was back in Pujiltik by 2 PM that same day, having NOT paid $50, but being unable to say publicly how it was arranged.
While heading back home I passed time thinking about whether in Nature there are analogies to a government's corrupt local officials.
First I considered the fact that Mother Nature does seem perfectly content tolerating fairly high levels of parasitism, robbery and deception. Think of mistletoe, the nectar robbery in flowers I've written about several times, and orchid blossoms getting themselves pollinated by looking like the mates of certain insects.
However, does Nature put up with anything like "the bite?"
When government officials invent or bend the law, it's a little like a mutation arising in Nature. In both cases it's a matter of accepted procedures being unexpectedly changed. In Nature the incidence of mutations is fairly rare, most mutations hurt the organism or kill it, but rarely a beneficial mutation does come along and evolution is advanced.
The kind of ten-dollar corruption at the Guatemalan border, however, is not rare, appears to go unpunished (I endured similar problems at the same crossing years ago), and I can't imagine any eventual long-term benefit arising from it.
The closest analogy in Nature I can find to such unimaginative, small-time, common corruption is that of an ailing body's spontaneous production of cancer cells.
ANT BENEATH A LEAF
The other day I passed beneath a water-starved Castor plant, looked up, and saw what you can see at http://www.backyardnature.net/n/08/080317al.jpg.
In the picture an ant is feeding from one of a pair of nectar-secreting glands atop a yellowing leaf's petiole.
As I stood looking I wondered what it felt like being that ant exactly where it was, doing exactly what it was doing.
I tried to imagine being ant size adhering to a translucing, yellow platform amidst converging lines, the blue sky summery-clouded beyond. Feeding on musky nectar. My silhouette elegantly etched against my whole immediate world. My own scent-trail and the trials of other scents leading down the petiole, ¿to somewhere better than this?
Such identity-trading exercises are useful. We humans survive only because we're accepted members of an intricate web of interdependent beings. Sometimes we really should reflect on how those other beings are feeling, what they need, and how and why we should share the world with them gladfully.
Other organisms' perspectives are relevant. Humans share 98% of our genetic makeup with chimpanzees, so it's to be assumed that chimps feel a lot like we do, even if we can't understand what they're telling us. If humanity keeps evolving, something later will emerge from us as different from us as we are from chimps, and that new kind of being will "feel" things more complexly than we by about the same degree we "feel" more complexly than chimpanzees. Will that new brainier-than-humans species ever think it worthwhile to reflect on how any lowly human must be feeling?
If they don't, they'll last no longer than we humans will if pretty soon we don't concern ourselves with the feelings and value of other organisms.
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