February 28, 2010

A GOOD MOTMOT PICTURE
We've frequently spoken of the Turquoise-browed Motmot so famously known in Maya as the Toh. I see them almost daily but never get used to their gorgeous colors. This week one landed near my door and posed while I fumbled with my camera. You can see him at https://www.backyardnature.net/yucatan/tqmotmot.jpg.

The missing barbs in the long tail are typical of most motmot species. I've read both that the missing barbs fall out by themselves, and that the bird removes them, so I don't know which is the case. Tohs twitch their tails sharply back and forth as they perch, causing some people to call them Tick-Tock Birds.

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A FLYCATCHER PUZZLE
Eastern US birders know the Great Crested Flycatcher. He's a robust bird with a low crest, rustiness flashing in his wings and tail, and calling with loud, sharp, ascending WHEEP, WHEEP, WHEEPs. The calls remind me of summer because they're so typically heard up north during the summer, especially at woods edges next to fields. In the East there's nothing similar to the Great Crested.

Great Cresteds overwinter here in the Yucatan, plus we have three other very similar, permanent-resident flycatcher species: the Yucatan; the Dusky-capped, and; the Brown-crested. All four look-alike species are members of the genus Myiarchus.

Therefore, I just didn't know which flycatcher I had the other day when one perched in a leafless Kikché tree 20 feet away. I got pictures of him, though, seen at https://www.backyardnature.net/n/10/100228bh.jpg.

Of the four species, the Yucatan and Dusky-capped species hang together because of their smallish bills. You can compare the above bird's bill with the smaller bill of a Yucatan Flycatcher, probably, seen in 2008, at https://www.backyardnature.net/yucatan/becardgc.htm.

Our bird's bill is clearly larger than that one. So, this week's bird is either the Great Crested or the Brown-crested Flycatcher. Distinguishing those two species can be tricky. The Brown-crested is generally paler overall than the Great Crested, his belly isn't as yellow as the Great Crested's, the contrast between his yellow belly and grayish throat isn't as sharply defined, and the Brown-crested's lower mandible is predominantly black while the Great Crested's is extensively fleshy at its base. These traits are hard to see in poor light, though.

Once I could compare my pictures with field guide illustrations I came to this conclusion: Brown-crested Flycatcher, MYIARCHUS CRINITUS.

Brown-crested Flycatchers WHEEP, WHEEP, WHEEP similarly to Great Cresteds, even occasionally now, in the dry season. My impression is that here Brown-cresteds are the most common of Yucatán's four look- alike Myiarchus flycatchers.

Brown-cresteds, called Wied's Crested Flycatchers in older field guides, are distributed from southern Texas and the US desert Southwest south to Costa Rica, with a another population from Columbia to northern Argentina.

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SCALES ON A SNAKE HEAD
Walking across the employee's badminton court next to the church this week I came upon a two-ft snake, shown at https://www.backyardnature.net/n/10/100228sn.jpg.

Its lack of conspicuous field marks suggested that it'd be hard to identify this snake without knowing some technical features, so I caught it and made some close-up pictures, one of them shown at https://www.backyardnature.net/n/10/100228so.jpg.

In identifying look-alike snake species, nothing is as helpful as the scale patterns, especially those on the head. Scale patterns are pretty stable within species, but they vary consistently among the species.

The scales on this snake's head showed up so nicely that I created an image for my website's snake identification page, labeling each head scale, now seen at https://www.backyardnature.net/pix/snakscal.jpg.

From Jonathan Campbell's Amphibians and Reptiles of Northern Guatemala, the Yucatán, and Belize I made a list of all the snake species it could be, based purely on whether they were present in the Yucatán, and whether the illustrated snake halfway looked like my badminton snake. Here was my list of possibilities:

Of these I least thought it would be the centipede-eater because those are smaller. Campbell says that Yucatán Dwarf Centipede-eaters usually have 6-7 supralabial scales, while ours has 8. They have 6 infralabials, while ours has 7. Also, they have NO loreal scales, while ours has a good one. Therefore, this is not a Yucatán Dwarf Centipede-eater.

Next, the head shape didn't seem quite right for it to be a Common Tropical Ratsnake. That species has 8 supralabials like ours, but 11 infralabials, while ours only has 7. The difference in infralabial number is so great that I disqualified the ratsnakes.

So, does our snake match the Mayan Golden-backed Snake's scales count? Campball says that that species usually has 6 supralabials while ours has 7. It has 8 infralabials, which ours also has. It also has 15 rows of side scales, which is what I counted when I had ours in my hand.

Thus, based on scale patterns, this snake best fits the description of the Mayan Golden-backed Snake, SYMPHIMUS MAYAE, described by Campbell as a little- known snake inhabiting tropical dry forest, as diurnal (out during the day), and feeding mostly on grasshoppers, crickets and katydids. Especially because it's "little known" I'd love to think it's this species.

However, the coloration isn't quite right (no golden back, for one thing) and Campbell shows a more slender-tailed snake, so I can't be 100% sure of the ID. Campbell's photos are mostly of Guatemalan snakes, and sometimes our Yucatec ones look significantly different. Maybe ours is one of those species I disqualified because of coloration.

Anyone out there with a more expert opinion?

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A SPREADWING SKIPPER
Along a sunny trail at the forest's edge a small, black butterfly landed on a white limestone rock, seen at https://www.backyardnature.net/n/10/100228bf.jpg.

It struck me as unusual because not many almost-pure black butterflies are seen. Also, it had a thick, big-headed body and densely hairy wings like many skippers have, yet most skippers I run across hold their wings at 45° angles, or at two diagonal angles, not horizontally as this one did.

The next day Bea in Ontario came back with a verdict: The closest picture she could find on the Web matching it was of the Mazans Scallopwing, Staphylus mazans, a "Spreadwing Skipper" of the Skipper Family, the Hesperiidae. That big family embraces about 788 Mexican species, and our skipper's subfamily, the Pyrginae, includes about 212 Mexican species, so there may be lots of look-alike relatives.

Mazans Scallopwing, however, is documented only from the US border region with Mexico, south to about Veracruz, so if we have them in the Yucatán ours must represent an "island" or disjunct population. Also, my skipper seemed blacker than that species.

Bea with her own doubts wrote to Paul Opler, who oversees the wonderful Butterflies and Moths of North America website at http://www.butterfliesandmoths.org.

Paul quickly replied that he just couldn't say what it was. He explained:

So, there: Basically we pushed the ID process as far as an amateur can without sacrificing a butterfly to dissection, and even with a decent photo all we can say is that probably it's in the Subfamily Pyrginae, which embraces some 212 Mexican species. It's a good lesson though, reminding us that, especially in Mexico where species diversity is greater than in the North, and where much fewer studies have been made, sometimes you just can't come up with a final answer.

Caterpillars of Mazans Scallopwing, which our skipper must be closely related to if it's not the same thing, feed on members of the Goosefoot Family, the Chenopodiaceae, which Spinach also belongs to, and the Amaranth Family. Just last week I told you about our common Yellow Joyweed, which was a member of the Amaranth Family, so this is a good place for scallopwings.

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YUCATAN CAESALPINIA FLOWERING
For a couple of weeks pleasing, diffuse explosions of yellowness have adorned roadside woods edges, rather like Redbud-pink soon will appear up North, as shown at https://www.backyardnature.net/n/10/100228ca.jpg.

The small trees themselves are mostly leafless now, so the greenness in that picture is provided by other trees. If this yellow-flowered tree were planted alone in a park, it'd draw an audience, but here it's just a weed tree struggling for space. Once its flowers are dropped, it'll become just another nondescript tree. Up close, the blossoms, about the size of a US 25-cent piece, reveal the family the tree belongs to, as seen at https://www.backyardnature.net/n/10/100228cb.jpg.

And if that doesn't ring a bell, maybe the tree's twice-compound, or "bipinnate," leaf -- a little reminiscent of a Honeylocust leaf -- will, as shown at https://www.backyardnature.net/n/10/100228cc.jpg.

If you see a flower with five petals arranged with bilateral symmetry, with ten stamens united at their bases into a cylinder around a slender ovary and stigma-tipped style, and the plant bears compound leaves like this, you just have to think "Bean Family," and that's the case here. Honeylocust and Redbud trees also are in the Bean Family, so it all hangs together.

Our yellow-blossomed tree is the Yucatan Caesalpinia, CAESALPINIA YUCATANENSIS. we've run into several trees that burst into lavis yellowness like this, but they were usually Cassias, also Bean Family members and also with five-petaled, bilaterally symmetrical flowers. However, Cassia leaves are only once compound, or pinnate, as opposed to bipinnately, compound. If you can't visualize these leaf differences you might check out our leaf page at https://www.backyardnature.net/lf_confg.htm.

In the diagram at that page's top, Leaf A is a classic pinnately (once-pinnate) compound leaf. Leaf G, like our Caesalpinia leaf, is bipinnate.

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CHENILLE-PLANTS FLOWERING
In the shadowy garden spaces between Hacienda Chichen's cabins, below the palms and other tall trees, a big-leafed, brittle-stemmed shrub about eight feet tall nowadays is decked with such vibrantly red flower spikes that they seem lit from inside, as shown at https://www.backyardnature.net/n/10/100228ac.jpg.

That's a female Chenille-Plant, also called Redhot-Cattail, Philippines Medusa, Foxtail and a host of other names. It's ACALYPHA HISPIDA, a member of the same family as the Poinsettia, the Spurge Family, the Euphorbiaceae. Chenille-Plants are "dioecious," meaning that each plant bears unisexual flowers of only one gender. In the picture, the long, red spikes, which grow up to 18 inches long (46 cm), bear only female flowers.

The fuzzy appearance is produced by the flowers' long, much-branched styles, the style being the ovary's "neck," which terminates at the top as a pollen-receiving stigma.

Usually Shenille-Plants are propagated by cuttings. Since the inflorescences of male plants aren't regarded as pretty, usually cuttings are made only from female trees.

Chenille-Plants apparently are native to Oceania, though they have escaped in many tropical and subtropical environments.

By the way, chenille is defined as a soft, tufted cord of silk, cotton, or worsted used in embroidery or for fringing, or else a fabric made of this cord, commonly used for bedspreads or rugs.

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ANGLEPOD FRUIT
Hiking to Pisté to buy fruit, the moment I saw a certain thing hanging in a tree beside the road I knew I'd be writing to my old friend Ulli at the University of Bayreuth in Germany. Ulli happens to be one of the world's leading experts in a particular section of the Milkweed Family, and the thing hanging in the tree was a four-inch-long (10 cm) fruit of a twining vine in his group. You can see the interestingly four-winged pod at https://www.backyardnature.net/n/10/100228ap.jpg.

In the southeastern US similar pods are produced by a halfway uncommon Milkweed-Family vine called the Eastern Anglepod, Gonolobus suberosus, but that species doesn't occur in Mexico.

By the next day I'd sent Ulli the picture and he'd replied, saying that he instantly thought that it was the genus Macroscepis, and he noted that in the list I'd sent him, of species in the Milkweed Family found in the adjacent state of Quintana Roo, MACROSCEPIS DIADEMATA is noted. Therefore, we're guessing that that's what our plant is. I think that the genus Macroscepis fairly recently has been split from the much larger genus Gonolobus.

Ulli asked for seeds, for he grows the plants he studies in greenhouses at the University, doing genetic sequencing on them. He says that this is a very interesting genus, and that the only representative he has of it is remarkable because its flowers produce nectar that changes from clear to black! He further says that black nectar occurs in scattered species in the family, but nobody knows why.

So, here we have something little know, something that simply by posting a picture of it and saying that in February the pod was found in central Yucatán, we're contributing information that someday somebody will be glad to have. And if I can get seeds to Ulli, maybe someday he'll publish something about it himself.

Makes me feel good.

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LEARNING TO SEE
On the Internet I came across the book review you can read yourself at http://www.ralphmag.org/CO/blind.html.

The book reviewed was Space and Sight by Marius von Senden. When surgeons first learned how to perform safe cataract operations they operated on dozens of people of all ages who had been blinded by cataracts since birth. Von Senden collected accounts of such cases.

He found that, in general, newly sighted people were dazzled by the color-patches they experienced for the first time, and they were pleased, learned quickly to name the colors, but they found the rest of seeing tormentingly difficult.

Newly sighted people have little or no sense of form, distance, and size. Often they interpret stimuli in novel ways. For instance, one patient referred to lemonade as square because it was sharp on his tongue the way square things have sharp corners.

For me the most interesting observation, however, was that learning to see proved to be overwhelming for many patients. It oppressed them to realize, if they ever did at all, the world's size and complexity. They didn't like discovering that all along they'd been visible to other people, often unattractively so. In fact, many refused to use their new vision, continuing to examine objects with their tongues, and eventually lapsing into apathy and despair.

Those who did finally master vision, especially the young, often underwent profound personality changes. One doctor commented on "the rapid and complete loss of that striking and wonderful serenity which is characteristic only of those who have never yet seen." The newly sighted often grew ashamed of their former habits. They didn't like having to start hustling to look acceptable to others.

In a way this is similar to the lady I wrote about some time ago who lost the use of the side of her brain that makes sense of things. As her brain healed, she regretted learning how complex reality was, and what challenges lay before her if she were to survive. That essay is still at the bottom of the page at https://www.backyardnature.net/n/08/080707.htm.

It's worth reflecting on these matters because today science enables us to see and think about the universe around us in ways impossible for our ancestors. In an intellectual and spiritual sense, it's as if we've been operated on so that now we have a whole new sense available to us, or a whole new section of brain with which to think thoughts never before possible.

Yet, as with the newly seeing blind and the lady who lost the use of the sense-making half of her mind, most of us find it hard or impossible to expand our vision of the world in ways our ancestors could not. Most of us stick to old beliefs and ways of thinking no matter what evidence is placed before us.

To save Life on Earth from biosphere-destroying human behavior, however, we must not only see and think about what science and technology reveal to us, but also put the revelations into practice, even if it's "tormentingly difficult."

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Best wishes to all Newsletter readers,

Jim