JIM CONRAD'S
NATURALIST NEWSLETTER
Issued from Hacienda Chichen Resort
adjoining Chichén Itzá Ruins in
YUCATÁN, MÉXICO

May 9, 2010

CLAY-COLORED ROBIN SINGING
Without a tripod, and pushing my little pole-steadied hand-held to 20X, I don't think I'll ever make videos that don't bob around. Still, I'll probably keep making them, if only to record the sounds. In this week's Clay-colored Robin video it's the song that counts.

For, each early morning and late afternoon the chorus of countless Clay-colored Robins singing is simply majestic -- not only because of the sheer volume produced by innumerable birds, but also because this bird's song is particularly pleasing to hear, so varied, sometimes a little echoic, like distant bells.

You can hear (and see a wobbly video of) a Clay- colored Robin singing in deep shadows, with a late-afternoon temperature in the lower 90s, at the bottom of our already-existing Clay-colored Robin page at http://www.backyardnature.net/mexnat/turdgray.htm

You might enjoy skimming the other text entries on that page, by the way, especially the second one dealing with nest building and leks, for this species has a family structure that some religious fundamentalists wouldn't want to hear about.

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A FLOOD OF YELLOW-GREEN VIREOS
While the callings of Clay-colored Robins have been dominating each day's early and late bird-choruses, there's been another bird species calling, just as numerous, just as persistently singing, but less noticeable because the birds are smaller and their songs softer and simpler. They're Yellow-green Vireos, VIREO FLAVOVIRIDIS, and you can see one with his wings held out and his mouth agape because of the heavy heat at http://www.backyardnature.net/n/10/100509yv.jpg.

Yellow-green Vireos are among the few migratory species who arrive to nest in the Yucatan at this time of year from the south. This fall they'll return south. The species breeds during the "summer" from southern Texas to Panama, and winters in western Amazonia in South America.

Yellow-green Vireos look, sound and behave very much like the Red-eyed Vireos that breed up North, even having red eyes. You can think of a Red-eyed Vireo as employing black mascara to highlight its white eyebrow, while the Yellow-green Vireo has the same facial pattern, just without the mascara. Also, Yellow-greens are yellow along their sides and on their undertail coverts, while Red-eyeds are whitish.

The Yellow-green's song strikes me as an even mingling of the Red-eyed's monotonous, high-pitched phrases and the House Sparrow's slightly tremulous chirping.

Like in Northern Red-eyed counterpart, Yellow-green Vireos suddenly arrive in a vast migratory wave already lustily singing and filling treetops with activity. Usually they stay too high up for me to get good photos of them. The above picture presented itself only because the bird shown was chasing another bird who'd tried to escape by flying lower than usual.

The North's Red-eyed Vireos pass through here only during migration. Howell says that Red-eyeds are mostly silent during migration.

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LEAFCUTTER ANTS VIDEO
Late Tuesday afternoon a line of leafcutter ants formed alongside my hut, many carrying leaf shreds. The line led to a fallen, leafing-out but wilting Gumbolimbo branch snapped off by high winds about three days earlier. The video is at http://www.backyardnature.net/mexnat/leaf-cut.htm.

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MYSTERY SKULL
When a friend told me that the bones of a chicken back were an iguana skull, and I believed it, another friend quipped that as a skull expert I was a good vegetarian. Therefore, when this week a skull turned up near where that chicken back had been unearthed, I grew very circumspect. Can you ID the skull shown at http://www.backyardnature.net/n/10/100509sk.jpg?

This time a friend told me that it was certainly the skull of a Tepescuintle, a piglike, large rodent the Maya used to eat a great deal of before Tepescuintles got scarce. The Tepescuintle skull I found on the Internet matched my discovery, so I started feeling confident.

However, just before my friend had come along saying it was a Tepescuintle skull, I'd shipped the picture to an address at "Skulls Unlimited International, Inc." where someone offered to identify skull pictures sent to them. Apparently that organization is associated with the Museum of Osteology in Oklahoma City. (http://www.museumofosteology.org)

The next day, Joey Williams, Director of Education there, replied:

Rabbit.

I sent him the Internet address of the Tepescuintle skull and he replied that that was a misidentified rabbit skull. He even returned my own picture highlighted and labeled to show what made the rabbit skull a rabbit skull, and you can see that at http://www.backyardnature.net/n/10/100509sl.jpg.

He writes:

Rabbit and hare skulls (Lagomorphs) are easily distinguished by two skull characteristics:

  1. Rostral fenestration... which is all the holes in the side of the animal's "snout" or rostrum, and
  2. A double set of upper incisor teeth.

From this exercise I deduce three facts: 1) I'm still not much of a skull identifier; 2) Don't trust everything you find on the Internet, and; 3) That Museum of Osteology web address is worth holding on to.

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EBIRD WEBSITE
Speaking of web addresses worth keeping in mind, Jarvis in North Carolina writes telling me about a new website describing itself as "amassing one of the largest and fastest growing biodiversity data resources in existence. For example, in January 2010, participants reported more than 1.5 million bird observations across North America!"

If you have bird lists you'd like to share, with a view toward helping scientists monitor the welfare of bird species (lists from Mexico welcome), take a look.

The main eBird website is at http://ebird.org.

Genral information is at http://ebird.org/content/ebird/about.

*****

ANOLE ANALYSIS
Speaking of easy IDs gone hard, last week I showed you the female Brown Anole, ANOLIS SAGREI MAYENSIS, shown at http://www.backyardnature.net/yucatan/br-anole.htm.

This week I was looking for the male, so when a dark anole came working along my pole wall not showing the female's white dorsal stripe I figured I had him. He's at http://www.backyardnature.net/n/10/100509an.jpg.

However, once I got the picture on my laptop's screen, his patterning turned out to be more like that of the closely related Bourgeau's Anole, though really it wasn't a good match for any of the pictures in Campbell's Amphibians and Reptiles of Northern Guatemala, the Yucatán, and Belize. I sent the picture off to James in Washington State, who helped with my last reptile riddle, and he replied that he couldn't be sure, either.

However, James noted that both species are very variable, and that the Bourgeau's Anole is more of a forest dweller, while Brown Anoles are "quite happy in a human-altered landscape, to the point that it is a human commensal in many places." Also, he said that Brown Anoles should show something of a ridge, or "keel," running down the top of the tail, while Bourgeau's Anoles don't have that.

Well, in the above picture, if you stare long enough at the end third of the creature's tail, you'll begin seeing a thin, pale line running down the middle, that well could be a "keel."

So, after all, probably this is the male Brown Anole, but I just can't be sure.

*****

YUCATAN PIPER
Along a shadowy forest trail I encountered a head-high bush bearing the remarkable structure shown at http://www.backyardnature.net/n/10/100509pp.jpg.

It was easy to identify this a member of the very distinctive and common (in humid American tropics) black pepper genus, Piper, but it certainly was an unusual species. First, you can see that in this species' leaves several strong veins radiate from the leaf bottom. In the leaves of most plants, including Pipers, there's a single midrib running down the blade's center, and secondary veins branch from that.

The most remarkable feature, however, was the erect flower cluster with its individual tiny flowers on stalks. Not many of the genus Piper's hundreds of species produce stalked flowers. A while back we met the Rough-leaved Pepper, a common Piper species here with typical flower spikes, which you can compare at http://www.backyardnature.net/yucatan/piper-am.htm.

This new Piper with stalked flowers is PIPER YUCATANENSE, occuring from Mexico to Panama.

At http://www.backyardnature.net/n/10/100509pq.jpg there's a close-up of the stalked flowers. The green, spherical items are the ovaries, which will develop into black-pepper fruits -- peppercorns such as those you buy for grinding in your peppermill. Commercial peppercorns are produced by a different Piper species, however, Piper nigrum, a native of tropical Asia.

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DURANTA FLOWERING
These days along certain woods trails a bushy shrub or small tree is laden with the handsome flowers shown at http://www.backyardnature.net/n/10/100509dt.jpg.

If the lilac-colored, bilaterally symmetrical flowers arrayed in racemes remind you of the little dog-faced flowers of verbenas or lantanas, there's a good reason, for this is a member of the big Vervain Family to which those plants also belong. It's DURANTA REPENS, native from Mexico to Brazil. It's such a pretty plant that horticulturalists have developed any number of cultivars from it, some with variegated foliage, some with white flowers, etc. The plant goes by so many names -- such as Golden Dewdrop, Pigeon-Berry and Sky-Flower -- that many English speakers just refer to it by its genus name, Duranta.

You can see that nectar-seeking insects are attracted to Duranta's flowers, which even provide a nice landing pad for pollinators (the corolla's expanded lower lip), and directional lines running up the lip, leading to the hole holding the nectar (nectar guides).

This plant native to the Yucatan should be propagated much more than it already is.

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GUINEA GRASS
I've been waiting for a certain very large, coarse grass to flower so I could identify it, and now it's flowering. In spots where maybe 25 years ago cattle were grazed, this grass forms savanna-like openings in the forest, the tough blades waist to shoulder high. Where trails enter open spaces caused by treefalls, this grass might form a chigger-infested barrier you have to plow through. A small clump of it with its flower head seven feet high (2.1 m) is at http://www.backyardnature.net/n/10/100509gg.jpg.

A closer look at the flowering head, a panicle, is at http://www.backyardnature.net/n/10/100509gh.jpg.

Individual spikelets are shown at http://www.backyardnature.net/n/10/100509gi.jpg.

In that picture the brown, dangling items are pollen- producing anthers attached to threadlike filaments. The purple, fuzzy (plumose) items are female stigmas filtering the air for male pollen. The stigmas reside atop a short, necklike style, which tops the hidden, oval ovary, which will mature into a grass fruit, the future grass grain.

These spikelets are typical of the genus Panicum, in which are found the so-called Panic Grasses. In my Flora of McLean County, Kentucky, produced for my Master's Thesis, Panicum was the most prolifically speciating of all grass genera listed, represented by a dozen Panicum species. Panicums produce open flower heads like the one in the picture (flowers in "loose panicles"), with each spikelet containing a single floret. Grass flower anatomy can be reviewed at http://www.backyardnature.net/fl_grass.htm.

Knowing the genus, it was easy to look at a list of Panicums known to occur in this region and pick out which species this could be. So, what we have here is Guinea Grass, PANICUM MAXIMUM, native to Africa and Yemen but introduced into the tropics worldwide. The species grows naturally in open grasslands, under or near trees and shrubs and along riverbanks.

In much of the tropics Guinea Grass is valued as a species tough enough to survive the tropics' heat and droughts, yet providing good forage for livestock. Its blades contain an unusually high amount of protein. In many cultures, grass is cut at one location, then carried home in bundles to feed to tied-up or fenced-in livestock. Guinea Grass with its long, fairly stiff blades is appreciated for the ease with which it can be carried.

When you're hot and sweaty and have to crash through a lot of scratchy, non-native, tick- and chigger-infested Guinea Grass, it's hard to have good thoughts about this species. However, knowing how useful it is, and how pretty its flowers are up close, maybe some grudging admiration can be spared for it.

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BIG AECHMEA BROMELIAD FLOWERING
Bromeliads are tufted plants usually living on tree branches, though Pineapple plants are notable terrestrial bromeliad exceptions. Spanish Moss plants are bromeliads. Forests of the humid American tropics wouldn't be nearly as beautiful and otherworldly without their bromeliads.

In the Yucatan's arid, scrubby, northwestern corner few bromeliads are to be seen but as you travel southeastward average annual rainfall increases, and so does the occurrence of bromeliads. Here in the central Yucatan it's just becoming rainy enough for bromeliads to appear here and there in impressive, tree-garden arrays. Nowadays one of the landscape's most eye-catching splashes of color is provided by our hippopotamus-size bromeliad, AECHMEA BRACTEATA, which is flowering. You can see a typical plant at http://www.backyardnature.net/yucatan/aechmea.jpg.

That picture was taken two summers ago in late August near Sabacché, Yucatan, when the plant bore only fruits. In the picture the reddish, arching item at the left is the paniculate fruiting head subtended by several red, long, slender, bracts (modified leaves). The fruits are the pea-sized, spherical items arrayed in great numbers along the panicle's side branches.

Over a month ago our Aechmeas began issuing new flowering heads. The heads themselves remained green or greenish yellow but the long bracts were red almost from the start. I've been waiting for the flowers to appear but this week I realized that the plants have been flowering for a long time, just that the flowers were so small, inconspicuous and ephemeral that I've been overlooking them. You can see a yellow, hardly opened blossom with an ant for scale at http://www.backyardnature.net/n/10/100509ae.jpg.

That's a fully developed flower; I've not seen flowers more open in this species.

The ant is collecting nectar. Aechmea bracteata must produce a lot of nectar because most plants I find host many ants, some of them carrying large, shiny globules of nectar between their mandibles.

Besides nectar, Aechmea bracteata provides yet another important service to the local ecosystem by gathering rainwater where each of its blades connects with the center of the plant, forming "inter-leaf spaces". On the internet an abstract of a scientific paper on Aechmea bracteata's ecology reports on a large diversity of aquatic life in inter-leaf space pools -- mostly fly larvae -- as well as terrestrial animals, which are mostly ants, cockroaches, mites and springtails.

A typical clump of Aechmeas, such as in the image from Sabacché, consists not only of one or more flowering mature plants but also there are immature shoots arising from the mature shoots' bases. The immature tufts are called "pups" by bromeliad enthusiasts. Also, there are dead or dying, already-fruited shoots. Bromeliad shoots typically die once they've flowered, though the dying may take a year or two. Dead shoots host their own special communities of animals, mostly invertebrates that eat dead organic matter (detritivores), and ants.

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YELLOW PASSION-FRUIT FLOWERING
In last February's Newsletter we met our fruiting Yellow Passion Fruit vines, still shown at http://www.backyardnature.net/yucatan/passion.htm.

Now those same vines are flowering, gorgeously so. You can see a three-inch-across (7.5 cm) blossom at http://www.backyardnature.net/n/10/100509pf.jpg.

Passionflower blossoms display some unusual anatomy. You might enjoy figuring out what the various parts are of the blossom in the above picture by referring to my Passionflower page, with parts labeled, at http://www.backyardnature.net/fl_passn.htm.

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BASIL SEEDLINGS DEPLOYING SOLAR COLLECTORS
With the rainy season approaching I've sown some seeds, planning on some gardening. What a pleasure seeing seedlings emerge, such as those at http://www.backyardnature.net/n/10/100509bs.jpg.

Those are Basil seedlings grown from seeds collected from Don Filomeno's past-prime, dying-back plants. Like the tomato and hot-pepper seedlings grown from seedy leftovers in the kitchen, as soon as these seedlings broke the soil's surface they deployed two special leaves, their cotyledons. In most plants, including Basil, cotyledons are a little different in shape from future leaves.

Basically a flowering plant's cotyledons are solar collectors. Their job is to collect sunlight energy for fueling the magical photosynthesis process that produces carbohydrate, which is an energy source that can be stored in the plant's body. Once the cotyledons photosynthesize enough carbohydrate to fuel untold numbers of chemical processes, then the plant begins growing its stems, leaves, flowers and fruits.

Nature is offering profound wisdom here. Here's the teaching:

If you're a complex organism on Earth planning on doing complex stuff needing energy, but you're not into parasitism, preying on other living things, increasing global warming by burning fossil fuels, or putting up with nuclear accidents and waste, the very first thing you need to do is to deploy solar energy collectors.

Here at the beginning of our rainy season suddenly the whole landscape has gone from scrubby brown and gray to lush, shadowy greenness. Wherever you look burgeoning, irrepressibly sprouting, leafing-out greenness conveys the message: "Deploying solar collectors, deploying solar collectors... "

The above picture of the two Basil seedlings was taken just as the big oil spill in the Gulf of Mexico began moving onto the US coast.

How wise my little Basil seedlings are. How beautiful is their simple dedication to living sustainably, and leaving behind a world in at least as good a shape as they found it in.

*****

Best wishes to all Newsletter readers,

Jim