March 27, 2011

CIRCULATING BUTTERFLIES
Most days by about noon, when it's in the 90s (+32°C) and the sun beats heavily on the skin and soul, something remarkable happens: Dozens of butterflies flit about the open area before the hut, circling and circling, as if somehow circling were exactly what they wanted to do. A friend asked me what was behind it and honestly all I could think of to say was "joy."

Various species are involved -- mostly White and Yellow Angled-Sulphurs, Orange-barred Sulphurs and Dark Kite-Swallowtails. I never see them mating, though, so it isn't a courtship display, I guess. I'm not really sure what's going on. Anthropomorphically one can say that it looks like those butterflies simply enjoy circulating in a cloud with one another. But we're told that anthropomorphism blinds us to the ways other species perceive the world. I guess that that's true, though sometimes also it helps us understand their behavior, I'm sure.

At You-Tube I've uploaded a rough video from my digital camera showing what it looks like. It's at http://www.youtube.com/watch?v=efXdFjoGoNk

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KITE-SWALLOWTAILS AQUIVER
Sometimes Dark Kite-Swallowtails separate themselves from the butterfly cloud circulating before the hut, land very near one another on ground I've moistened that morning with the watering hose, and vigorously quiver their wings.

Who knows why they do this? One guess is that it's very hot there on the moistness-darkened soil, and the quivering keeps cool air circulating among them. Another is that predators might be confused by all the rippling images. However, elsewhere dense, similar sized clusters of other butterfly species often sit perfectly still, and it's just as hot with them, and they're just as vulnerable to predators.

A video showing a typical group quivering their wings is at http://www.youtube.com/watch?v=Dq9PA0C-Nh0.

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A MACHO ROBBER FLY
On a chilly morning as the sun's first rays slanted in from the east, a robber fly, genus EFFERIA, warmed sunbathing on a leaf next to my compost heap. Since he looked like he'd stay still long enough to get the camera set up I got his picture. It wasn't until his image was on my laptop's screen that I saw something remarkable about him. Can you see what it is at https://www.backyardnature.net/n/11/110327rf.jpg?

What's that dark, hairy, clublike thing extending from his rear end? I sent the picture to Bea in Ontario who soon came back with the verdict:

The little fellow has what could be called his penis lying out in the sun warming beside the rest of his body. Male robber flies of the genus Efferia are famous for their oversized male genitalia, and now I see why.

Why would Nature create such a thing? On the Internet several pictures show mating robber flies, sometimes with the participants blithely feeding on prey they've just caught, so my impression is that robber fly genitals are big so that during lengthy copulations life can continue as usual without the genitals breaking off, which might happen if they were smaller. Then the question arises of why copulation continues for such a long time among robber flies, and there we can only speculate.

I read that in Arizona 22 species of Efferia of the Pogonias group are known, so who knows how many we have here, and which species this one is? As you might guess, identification in the robber fly genus Efferia is mostly a matter of microscopically examining the species' amazing genitalia.

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GRAY HAWK BEING BROWN
Probably the most commonly occurring hawk in our area is the Gray Hawk, with Roadside Hawks being fairly common, too. Adult Gray Hawks are Gray, and Roadside Hawks are brownish, so it sounds like an easy deal. However, juvenile Gray Hawks are brownish, so whenever you see a brownish hawk you have to look closely. A brown one -- front and back views -- is shown at https://www.backyardnature.net/n/11/110327hk.jpg.

That's a juvenile Gray, most easily distinguished from brown Roadside Hawks by its whitish face. Roadsides have pale eyebrows, but not such extensively pale "cheeks." Also, barring on the bellies of both juvenile and adult Roadside Hawks is horizontal, while on juvenile Grays it's indistinctly vertical.

You can compare the above picture with our brown Roadside Hawk showing nice horizontal belly-barring at https://www.backyardnature.net/yucatan/roadside.htm.

By the way, if our Gray Hawk atop the power line looks especially small, one reason may be that Grays are a small species. The North's Red-tailed Hawk has a wingspread of 48 inches, while the Gray's wingspread is only 35.

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BOURRERIA FLOWERING
Here during the last weeks of the dry season a surprising number of plants are flowering. I'm guessing that the wisdom behind it is this: Flower now to have seeds ready to germinate when the rains return in May and June.

Nowadays one of the most conspicuously flowering shrubs or small trees at shady woods edges is one with tortilla-size leaves and panicles of thimble-size, white flowers at the ends of branches, as shown at https://www.backyardnature.net/n/11/110327bo.jpg.

Mature blossoms have five brown-anthered stamens extending from their cuplike corolla tubes and alternating with the five petals, as you can see at https://www.backyardnature.net/n/11/110327bp.jpg.

If the leaves and flower anatomy hadn't cued me to this plant's family, those curious brown, bruise-like marks on the white corolla would have provided a strong hint. It happens that flowers in the Borage Family, the Boraginaceae, tend to bruise just like that. In fact this is a Borage Family member, a Bourreria, probably BOURRERIA PULCHRA, about which not much information can be found on the Internet.

The species is favored by local Maya beekeepers because it's regarded as an important source of pollen and nectar.

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LIANA ROOTS DESCENDING
Lianas are woody vines. The term liana is mostly used in the tropics, however. Northern botanists seldom use the word liana when speaking of woody vines up there, such as grapevines and poison-ivy vines.

Lianas constitute an extremely important element in the forest here. In fact, my impression is that no other forest type I've seen contains more lianas than our tropical evergreen/deciduous forest. A typical forest-edge view showing lots of lianas is at https://www.backyardnature.net/n/11/110327li.jpg.

Thing is, during these last weeks of the dry season our lianas rambling through treetops are especially active in dropping long, limber, ropy roots toward the ground. Where the roots touch earth they enter the soil, and then the liana gains an extra conduit of water and soil nutrients.

Interestingly, just inches before the roots touch the ground often they issue smaller rootlets, and one wonders how the root "knows" it's about to touch ground. I suspect that increased moisture and warmer night temperatures near the soil's surface triggers extra rootlet growth. You can see such near-ground rootlets of a high-climbing Philodendron at https://www.backyardnature.net/n/11/110327lj.jpg.

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"REGULAR" MISTLETOE IN THE YUCATAN
From here and there in Mexico I've reported on seeing "tropical mistletoe," genus Psittacanthus, which parasitizes trees just like "northern mistletoe," except that its flowers are large and red -- really striking. You can see examples of some at https://www.backyardnature.net/yucatan/psittaca.htm.

Psittacanthus mistletoe is common in the Yucatán, too, plus we have other species very similar to those seen in the northern temperate zone. A large bunch is shown in an Acacia tree at https://www.backyardnature.net/n/11/110327mi.jpg.

A close-up of its leaves and white fruits appears at https://www.backyardnature.net/n/11/110327mj.jpg.

Best I can figure, that's PHORADENDRON LEUCARPUM, the name now used to incorporate several species that in the past were considered separate -- species known as American, Eastern, Oak, Pacific, Western and Hairy Mistletoes. In our area there's a similar species, an endemic one, Phoradendron yucatanum, but that one's stems are squarish in cross section. You can see that our P. leucarpum has round stems.

I figured that any plant as unusual as mistletoe must be considered medicinal by the Maya, so I asked José the shaman. He says that if you have a wound that becomes sore and enflamed, sap from the mistletoe's succulent leaves should be placed around the wound, but not touching it. Also, a pulp of mistletoe leaves mixed with four other plants can be used to alleviate pains including headaches resulting from "bad winds" -- the "vientos malos" or evil winds that flow dangerously through the night.

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CORALVINE IN THE WILD
Throughout much of the year along roadsides, in weedy gardens, clambering over stone fences, etc., you see dense, viny gatherings of pink flowers like those seen at https://www.backyardnature.net/yucatan/coralvin.htm.

That's Coralvine, ANTIGONON LEPTUPUS, of the Buckwheat Family, the Polygonaceae, and we've already spoken of it a couple of times. What's new to me is seeing it out in the woods, not just in weedy areas and in town. The other day when I saw the vine climbing 20 feet into a Uaxhim tree (Leucaena leucocephala) deep in the forest, I thought it was something new. That plant is at https://www.backyardnature.net/n/11/110327cv.jpg.

I shouldn't have been surprised finding it in the wild, though, since it's a native Mexican plant. Probably the most surprising thing about it is that it's a native able to compete with the rankest alien weeds in abandoned lots and fields. In fact, in the southern US it's often planted for its prettiness, and frequently escapes into the wild up there.

Something interesting about the species is that its branches end in flowering racemes, and the racemes themselves end in tendrils. Usually we think of tendrils as associated with leaves or stems, not flower clusters. You can see a tendril-ending raceme at https://www.backyardnature.net/n/11/110327cw.jpg.

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PURPLE SPIDERWORT
You can see an attractive, purple-leafed, foot-tall herb doing very well growing in thin soil in cracks in the bedrock limestone outcropping in my front yard at https://www.backyardnature.net/n/11/110327tr.jpg.

A close-up of one of its pale purple, three-petaled, six-stamened flowers can be seen at https://www.backyardnature.net/n/11/110327ts.jpg.

That flower looks like it's emerging from some kind of slit, and it is -- from a long, narrow opening between edges of a branch-tip, folded-together leaf, as shown at https://www.backyardnature.net/n/11/110327tt.jpg.

Often grown as an ornamental in gardens, along borders, as ground cover and as a hanging plant, this plant goes by lots of English names. Maybe its most common one is Wandering Jew, but that name is shared by so many similar species that it's practically useless if you need to look up the plant. Other names include Purple Spiderwort, Purple Heart and Purple Queen. It's TRADESCANTIA PALLIDA of the Spiderwort Family, the Commelinaceae, native to Mexico's Gulf Coast region, but apparently not to the Yucatán.

The pretty flowers last for only one day, but usually a new blossom emerges from the slit the previous day's flower arose from, day after day for a good while. Older leaves die back leaving naked stems, which can give the plant a leggy look, but the plant is so vigorous that scraggly parts can be pulled out and new sprouts quickly form dense, new growth. If you're in a frost-free zone, however, be careful, because discarded stems often root and grow. In southern Florida, Australia and other places Purple Spiderwort is regarded as an invasive, hard-to-control weed.

In my front yard, however, its purple herbage is very pretty against the white limestone, and it thrives where other less vigorous plants wither from the limestone's reflected light and heat.

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CUMULUS HUMILIS
Nowadays on most afternoons small, cottony cumulus clouds appear in the sky. They're fair-weather clouds, not growing into anything that might produce rain. They materialize in the sky, travel a bit, and then vanish as newer clouds form around them. The other day as I returned from Mérida after dealing with visa issues, on the toll road toward Cancún I put my camera out the window and photographed what's shown at https://www.backyardnature.net/n/11/110327cc.jpg.

Our prevailing winds arrive from the east, so these cottony cumuli are coming toward us from the Cancún area. I visualize a fairly calm, relatively cool and humid layer of air streaming toward us from over the Caribbean, then when it passes over the Yucatán's afternoon-hot land, bubbles of warm surface-air rise up through it, cooling as they rise. If the rising bubbles are warm enough, maybe they'll form convection cells. When the air inside a bubble cools to a certain point, humidity in it condenses, forming the cloud.

Different kinds of cumulus clouds are recognized. In fact, the World Meteorological Organization, or WMO, regards "cumulus" as a "genus" category, exactly as with plants and animals, then there are various "species" of cumulus. Of cumulus clouds the WMO recognizes species such as Cumulus fractus, Cumulus mediocris, Cumulus mamma, and more. There are even cumulus varieties.

Our picture of clouds coming in from Cancún shows what's known as Cumulus humilis, "humilis" referring to something that's low or smallish. Cumulus humilis clouds are described as "fair weather clouds" with flat, light-grey bases and small, white-domed tops.

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BEA'S SUPER GOLD AWARD
Bea in Ontario, who often identifies butterflies for us, this week received my famous Bug-Eaten Leaf Award. She got the Gold for IDing a hundred species of plants and animals around her home. Moreover, she did it in style: She photographed every species. Her list with names hot-linked to their appropriate photos is at https://www.backyardnature.net/awards/g-can001.htm.

If you're looking for a Nature-oriented project for this spring or summer, keep the award in mind. The Bronze award is for identifying 33 species, the Silver for 66, and the Gold for 100.

The page telling all about the awards is at https://www.backyardnature.net/awards/.

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IF YOU MISSED LAST WEEK'S NEWSLETTER...
My impression is that while some Newsletter subscribers received last week's edition, most did not. If you missed it and want to see it, it's at https://www.backyardnature.net/n/11/110320.htm.

In fact, all previous Newsletters, starting with the one issued at my hermit camp on June 10, 2001, can be accessed at https://www.backyardnature.net/n/.

My Newsletter-issuing process messes up from time to time. Maybe my server experiences a breakdown or maybe my Newsletter publishing program is too primitive to handle the thousands of addresses on my subscription list. If anyone out there knows of a good freeware Newsletter program capable of handling a large subscription list, you might let me know.

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ROBIN MYTHOLOGY
Though the dry season won't end for several more weeks, our Clay-colored Robins already have begun calling. I suppose the idea is to coordinate the hatching of their nestlings with the first rains, when there'll be an outbreak of caterpillars and other soft-bodied insects feeding on fresh new herbage.

I've waited for this since last year's robin calls ended in July. For, while right now only one or two early-morning and late-afternoon birds are singing, soon there'll be several all around the hut calling at the same time, and then their echoic, fluty tones and ever-repeating, overlapping melodies will create an otherworldly sound that entrances and soothes, like Sufi dance music that can transport you into mindless dreaminess.

For me there's a powerful association between the robins' effervescing aural rainbow and the coming rainy season's lushness, its unrestrained greenness, and its innumerable, irrepressible germinations and sproutings, hatchings and lusty growth. Back during the robins' last calling a friend even visited the hut when the calling was most lucid, at dusk, to listen with me, so there was that, too, a time more gentle and meaningful than can be said.

In fact, during the eight months since the robins stopped calling, inside me there's arisen a mythology of the robins' callings. Like Pavlov's dogs with their bells, when I hear robins calling here in the dusty dry season I am stunned into a helpless nostalgia remembering all the tender lushness, the urgent arousings, births and rebirths of those rainy times.

I know I'm mythologizing, though, overemphasizing the exquisiteness of some details while selectively forgetting others. Certainly I'm suppressing memories of biting horseflies and mosquitoes, endless sweating, and all the stinking mildew of those rainy times when the robins' callings reached their peak.

But, we humans respond more fervently to myths than to everyday realities, so these days as the Clay-colored Robins return to singing I abandon myself to a reverie of their current calling. I let my spirit be brought into pastels, encourage it to harmonize with echoic yearnings maybe inappropriate for an old codger like myself... even as the first horseflies draw blood, mosquitoes reappear clustering outside my net, and even though this time no friend comes at dusk.

The mere singing itself brings pleasure enough, I tell myself. And, in fact, it really is beautiful that, once more, I'm here as the robins begin their calling.

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Best wishes to all Newsletter readers,

Jim