January 16, 2011

ORIOLES IN THE CEIBA
This week the Ceibas have been flowering much more prolifically than last year, and each morning each Ceiba has constituted nothing less than an animated and gaudy circus.

Beneath one tree you could stand and see dozens of orange or yellow and black orioles at one time -- mostly Altamira but also Hooded, Orchard, Yellow-backed and Baltimore. They, Melodious Blackbirds and Golden-fronted Woodpeckers were after nectar. You could see the woodpeckers' long, black, stiff tongues probing for nectar in the flowers' bottoms. The Squirrel Cuckoos and Turquoise-browed Motmot, however, were after insects, especially what looked like stingless Maya Bees.

A pretty picture merely hinting of what it was like is at https://www.backyardnature.net/n/11/110116cb.jpg.

That's an Altamira Oriole. A Yellow-backed Oriole is at https://www.backyardnature.net/n/11/110116cc.jpg.

Two shots of a Hooded Oriole are shown at https://www.backyardnature.net/n/11/110116cd.jpg.

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KILLDEER AT THE GARBAGE DUMP
Early week it was as hot as later in the week it was cold. One sizzling day when I visited the garbage dump just south of Pisté the wind stirred up fast-moving clouds of reddish dust as it swept across the barren acreage. The usual birds were there, dozens of Black Vultures, Great-tailed Grackles, and a Tropical Kingbird having great luck snapping up flies.

This time, however, there was something special, which I heard before seeing: From high in the sky there came a plaintive kill-DEEE, kill-DEEE, kill-DEEE, the call saying the name of the bird as I knew it growing up on the farm in Kentucky. Books call Killdees by the name of Killdeer, but I've never heard a bird pronounce the final "r." Four birds, their bright orange rumps flashing as they spread their wings to land, touched down on the road. You can see one who quickly ran into the garbage area at https://www.backyardnature.net/n/11/110116kd.jpg.

I've seen the Killdeer at other garbage dumps, so the species clearly has an affinity for dumps -- or at least for the broad horizons that land cleared for dumping provides. That day they seemed perfectly at home even with blinding dust clouds swirling around.

Many birders don't realize that the Killdeer is migratory. Back in Kentucky I didn't know it myself because we saw them year round in our flat, bottomland fields. The deal is that during the summer they nest throughout the US, plus northern Mexico and southern Canada, but spend their winters from the southern half of the US to El Salvador and Honduras. Thus the summer and winter distributions overlap in Kentucky and much of the southern tier of US states. During Kentucky's winters I must have been seeing individuals who nested in Wisconsin or thereabouts. Here in the Yucatan the Killdeer is strictly a winter visitor, though, and this is the first time I've seen one in the interior.

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JUMPING SPIDER
In late afternoon I sat reading beside the hut when a certain tickling came onto my leg. I ignored it but then it climbed onto my arm holding the book. It was the jumping spider shown on my well weathered skin at https://www.backyardnature.net/n/11/110116js.jpg.

A head-on view clearly showing six of its eight eyes is at https://www.backyardnature.net/n/11/110116jt.jpg.

Those pale brown, goggle-like disks facing forward are eyes, the four darker bumps along the top of the head are eyes, but really I'm not sure where eyes #7 and #8 are. I just read that "All jumping spiders have four pairs of eyes."

It took awhile to get those photographs. As soon as my lens approached the little being close enough for a shot, he'd jump onto the lens. It happened several times so clearly this was something he felt he needed to do.

I've enjoyed good luck getting help identifying my tarantulas, spiders and other arachnids at the free, online forum called Arachnoboards, accessible at http://www.arachnoboards.com/ab/.

Therefore, I uploaded there the two photos you just saw, waited several days, but -- much in contrast to previous posts -- no-one attempted to name my unknown, not even to subfamily. From this I can guess that the species doesn't occur in southern Florida. Species also occurring in southern Florida often are known to US hobbyists and specialists who help me out. Maybe we have a Yucatan specialty species here.

So, all I can say is that this is a jumping spider, which isn't saying much, since the Jumping Spider Family, the Salticidae, is the largest of all spider families, containing more than 500 genera and some 5000 described species. About 13% of all spiders on Earth are jumping spiders.

And you might guess from the pictures that a big thing about jumping spiders is that their vision is very sharp. They need that for hunting and navigating. They don't produce webs, but rather stalk their prey, and pounce on it.

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SIXANGLE FOLDWING FLOWERING
Some wildflowers, like certain lilies and orchids, look as if they're sculpted of wax along classic, elegant lines. Others, like dandelions with their simple explosions of yellow in fields of green grass, are like haiku spoken in a murmuring crowd. A six-ft-tall (1.8m) wildflower blossoming nowadays is like fireworks -- many bright-red flairs diffusely detonating in open spaces along trails through the woods and at woods edges. You can see the effect at https://www.backyardnature.net/n/11/110116di.jpg.

A closer look at an inch-long blossom is at https://www.backyardnature.net/n/11/110116dj.jpg.

The curved, two-lipped corolla is reminiscent of certain mint flowers, like Scarlet Sage, but the plant isn't square-stemmed and the fruits aren't composed of four nutlets. If you peek into the flower you'll find only two stamens. You can barely see the stamens' yellowish, oblong, pollen-bearing anthers peeping beneath the tip of the top lip. Extending a little beyond the top lip's tip and anthers is the whitish, stigma-tipped style.

This is a member of the Acanthus Family, the Acanthaceae. Since it occurs in southern Texas and Florida it has English names. Sometimes it's called False-mint but most books refer to it as Sixangle Foldwing. It's DICLIPTERA SEXANGULARIS, and from Florida and Texas it's fairly commonly distributed southward through the tropics into South America.

A field mark for the Acanthus Family is that leafy bracts or scales typically subtend each blossom. In the flower picture, at the branch tip, you can best make out a scale arising beneath the topmost unopened flower bud and rising up the bud's far side. Also in this family, flower styles -- the ovaries' slender "necks" -- are long and persist atop maturing ovaries. In the last picture, old, discarded corollas, looking like dirty paper, dangle from such styles.

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GINGER-LEAF MORNING-GLORY
With the dry season bearing down so, many herbs have died back and many trees have lost their leaves or are in the process of losing them. Even the weedy morning- glories that a month ago put on such a show are withdrawing, the landscape appearing ever browner and "wintry," despite the hot afternoons.

However, among the morning-glories, there's a handsome exception. Here and there along weedy roadsides a pink-flowered morning-glory with long, trailing, tough stems bearing leathery, semi-succulent, three-inch-broad (8cm), heart-shaped leaves twines among weeds and cascades onto the pavement. It's shown at https://www.backyardnature.net/n/11/110116ip.jpg.

This is a lot like the Goat's-foot Morning-Glory we saw scrambling across white, searing-hot beach-sand on the coast near Mahahual back in 2008. That species is at https://www.backyardnature.net/yucatan/goatfoot.htm.

However, notice that the Goat's-foot's leaves are notched at their tips, giving the leaf a goat's-foot shape, while leaves on our current species are pointed.

Our road-invading species is the Ginger-leaf Morning-Glory, IPOMOEA ASARIFOLIA, found throughout the world's tropics, with undetermined nativity. So little botanical info about it is available on the web that we need to describe it closely here. First, take a look at a longitudinal section through a flower showing stamens of very different lengths at https://www.backyardnature.net/n/11/110116ir.jpg.

The hairy calyx's rounded sepals of uneven lengths, and with conspicuous glands at the sepals' bases, is at https://www.backyardnature.net/n/11/110116iq.jpg.

The glandular midrib on the leaf's velvety underside is at https://www.backyardnature.net/n/11/110116is.jpg.

Most internet pages dealing with the species are concerned with the fact that sometimes livestock eat its herbage, get sick and die. Studies indicate that the problem may not be with toxins in the plant itself, but rather with a fungal infection that attacks the vine. The fungus is related to the ergots, who cause "ergotism," the main symptoms of which in humans are convulsions and gangrenous complications. Also, ergotism may include hallucinations, which cause some desperately unimaginative people to experiment with the seeds.

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LIVING WITH LOTS OF SUNSHINE
Ginger-leaf Morning-Glories are tough to survive at the hot, exposed edges of our asphalt roads, but maybe the prize goes to the mat-forming little plant shown at https://www.backyardnature.net/n/11/110116eu.jpg.

That's the Prostrate Sandmat, EUPHORBIA PROSTRATA, somehow sprouting up through asphalt at the road's edge. You can judge from the rusty bottle-cap at the top, right that the plant's leaves and flowers are exceedingly small, the leaves averaging about 1/5th inch long (5mm). A close-up of some leaves with a red fruiting capsule at the picture's top is shown at https://www.backyardnature.net/n/11/110116ev.jpg.

I needed to see that fruiting capsule, which is only about 1/20th inch high (1.4mm) because those stiff, white hairs arising from the fruit's three corners distinguish the species from similar relatives. Prostrate Sandmat is native to the American tropics and possibly subtropics, but does duty as an invasive weed in many Old World tropical countries.

Pictures of Prostrate Sandmat are plentiful on the Internet but I find none as reddish as ours. The redness results from long hours of intense sunlight. Often you see plants that normally are green acquire a reddish color when overexposed to sunlight, for red pigment absorbs sunlight energy that might otherwise damage the plant's relatively fragile green chlorophyll.

Also our plant's pairs of leaves occur along the stems much closer together than normal. This is another adaptation to intense sunlight, the closer-together leaves tending to shade one another.

Up North members of the genus Euphorbia often are referred to as spurges, and a field mark helping us recognize them is that they issue a milky, acrid juice from wounded parts. You can see a freshly broken stem at https://www.backyardnature.net/n/11/110116ew.jpg.

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INCH PLANT
Speaking of mat-forming plants, back at Hacienda Chichen I went to check on the compost piles where fallen leaves end up. In heavy shade at the base of a Cedro tree there grew the fragile-looking little mat-forming herb issuing ankle-high flower spikes shown at https://www.backyardnature.net/n/11/110116cm.jpg.

The plant fascinated me because its semi-succulent leaves had parallel veins like grass blades, and their bases formed cylindrical sheathes around the stems, just like those of dayflowers, genus Commelina. Also, flower clusters were subtended by leafy bracts just as with the dayflowers. However, these blossoms lacked the conspicuous three petals so typical of dayflowers. This was something else, another variation on the theme of the Dayflower Family, the Commelinaceae, one I'd never experienced.

This is a native tropical American plant now growing throughout the world's tropics and beyond because it's often planted to form lush mats in gardens, to dangle prettily over pot sides, to hang from hanging baskets, and it often escapes into the wild. It's CALLISIA REPENS and because of its wide occurrence it goes by many English names, including Inch Plant, Bolivian Jew, Turtle Vine and Chain Plant.

Nearly all photos of Inch Plant on the Internet show sterile plants. It's the mat-forming, dangling-over-the-sides herbage people want to see, not the piddling little flowers. Still, those flowers are interesting and pretty by their own right, as seen at https://www.backyardnature.net/n/11/110116cn.jpg.

In that picture a cluster of flowers arises from the juncture of the stem and a leaflike bract. Three flowers can be made out, each one issuing five stamens and a single style tipped with a white, powder-puff-like stigma. Notice that each anther is composed of two baglike cells that later will split open to release pollen. The two cells are connected by tissue expanded above into a very unusual, conspicuous, white, sail-like flap. I'm guessing that the flap catches the wind and shakes the anthers to dislodge polen.

Callisia repens produces two kinds of flowers. The ones shown are bisexual -- bearing both sexes -- but sometimes pure female ones are produced, the stamens completely absent.

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GUTTATION
Nowadays at dawn the plants around my hut are wet with dew. As morning wears on the dew evaporates leaving behind on certain leaf margins lines of water droplets that seem too evenly spaced to have been left by dew. Such droplets on a blade of Boat Lily are shown at https://www.backyardnature.net/n/11/110116gu.jpg.

The droplets are formed by the process of guttation, something completely different from dew formation.

At night, most plants have their stomata closed, so transpiration -- natural loss of water -- doesn't occur. If the plant is growing in soil with high humidity content, excess water enters the plant because of a slight root pressure. The excess water, which mixes with various chemical compounds, then may make its way to leaf tips or edges where it is exuded into the air by special structures called hydathodes. That's guttation.

Maybe the most mysterious part of guttation concerns the slight root pressure that pushes water upwards even when the plant's stomata are closed.

Root pressure results when water in plant roots contains a higher concentration of mineral nutrient ions than water in soil outside the roots. Water molecules pass through root cell membranes from areas of higher water concentration (the soil) to areas of lower water concentration (inside the root, where water is diluted by so many mineral ions), causing pressure inside the root. The pressure pushes water up into the plant, even though the stomata are closed and thus unable to rid the plant of excess water the usual way.

Thus, the need for guttation...

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CABAÑUELA
Throughout Mexico, not just among the Maya in the Yucatán, these are days of the Cabañuela (ka-ba-NYE- la). During the Cabañuela, which coincides with the month of January, country folks learn what the weather will be like the rest of the year. Here's how it works.

Weather during the first 12 days of January is believed forecast what the weather will be like during the rest of the year, each day referring to the weather of a subsequent month. If it's unseasonably chilly and rainy on January 10th, then October should be unseasonably chilly and rainy.

But the procedure doesn't end here. Weather of January 13th should correspond to weather the following December, same as the 12th, for now the count continues, but in reverse order, the 14th being for November, the 15th for October, etc.

Arriving at January 25th, we change directions once again, but this time the 12 hours before noon correspond to January, the 12 hours after noon to February, the 12 hours of the 26th correspond to March, etc.

That takes care of all of January, except for the 31st. On that day, midnight to 2AM corresponds to December, 2AM to 4 AM to November, etc.

I'm told that if the forecasts contradict one another, you average them out.

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EXTINCTIONS
In my way of thinking Nature offers natural models, or paradigms, that provide guidelines for human behavior. For instance, at every level of Nature resources are recycled, so I reckon that humans would be wise to recycle, too.

One of the most compelling and powerful of Nature's paradigms is the manner in which life began small and simple and evolved to be much bigger and more complex. Sometimes when I'm tired or starting to feel cynical about things and wonder why I try so hard to get my ducks in a row, this is the paradigm offering the most convincing proof that I ought to continue my struggle. For, Nature advises to struggle onward, from small and simple to larger and more complex...

But, that simple insight needs at least one big qualifier. And that is, the history of Life on Earth includes some very serious setbacks. Earth's living things have survived at least five mass extinctions as well as many smaller ones.

The greatest of all mass extinctions occurred at the end of the Permian Period about 250 million years ago. The cause of the extinction is unknown, but it was attended by high levels of carbon dioxide, low levels of oxygen in the oceans and high levels of toxic gases. During this extinction about 96% of all marine species and some 70% of all land species went extinct.

Those numbers -- 96% and 70% -- are even more shocking than they seem at first glance because they refer to species, not individual living beings. All it took to maintain a species with male and female members was for a pair of individuals of different sexes to survive.

Mass extinctions have so profoundly influenced the evolution of Life on Earth that some would say that they have been necessary to keep evolution from loosing its creative momentum. After each extinction, always there was an explosion of diversity of new life forms and manners of doing things.

So, how do mass extinctions bear upon the teachings of Nature's paradigms?

If nothing else, knowing that today's mind boggling, majestically diverse and beautiful examples of life exist despite such past mass extinctions, we can find inspiration for keeping up the struggle forward when we suffer our own profound setbacks.

Also, keeping in mind Nature's proven disposition for periodically extinguishing great swaths of Earthly life, we can better keep things in perspective. It's harder to get hyper or obsessive about something when you remember that at any moment another mass extinction might occur.

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Best wishes to all Newsletter readers,

Jim