July 27, 2007
Last week I told you about our high-elevation, oak-loving Red-bellied Squirrels. We have squirrels in the hot, arid Jalpan Valley, too, despite the absence there of oaks and tall forests. I got a good look at the valley species the other day inside the Reserve office compound. He was perched atop a big heap of old tires being collected by the tree-planting guys who place the tires on steep slopes for erosion-control.
So, atop the top tire in this tire-heap the squirrel perched upright on his haunches the way a gray squirrel might when he's looking around, except that this tire-squirrel was perfectly still. Facing me directly he didn't twitch his nose, didn't wiggle an ear, in fact was so still that at first I thought he was a beer bottle someone had left there. But, no, when I moved closer he dove into the tire labyrinth and disappeared.
He was a Rock Squirrel, SPERMOPHILUS VARIEGATUS. With his foot-long, gray-brown body and eight extra inches of bushy tail, from a distance he looked like a regular gray squirrel. The most obvious difference was that across his back his fur was pale gray mottled with brownish black, so he looked as if he wore a gray and black calico shawl. If you have Flash Player installed on your computer or are willing to download it for free, you can see a video of a Rock Squirrel with a calico shawl just like ours eating flowers at http://www.desertusa.com/video_pages/rock_squirrel1.html.
Rock Squirrels are fairly common in the US's southwestern desert, extending north as far as Utah, and south as far as central Mexico.
I had to laugh, imagining how our Rock Squirrel must have felt when he discovered that mountain of old tires. For, the way a dog obsesses over odors, a pig over rooting in the soil, and songbirds over singing, I think Rock Squirrels must be perpetually fascinated with tunnels. Just imagine this critter's glee when he saw that his whole tire-mountain consisted of one circular tunnel after another, each in which he could go round and round as much as he wanted.
Rock Squirrels are polygynous. You might wonder what the difference is between polygynous and polygamous. Polygamy is a general term applying both to males having several wives, and females having several husbands. Polygyny, in contrast, just refers to males mating with several females -- polyandry being mating with several males. Moreover, I think of polygamy in a human social framework, while the term polygyny has more biological associations.
Rock Squirrels are not the same thing as ground squirrels, though both Rock and ground squirrels belong to the Squirrel Family and the Marmot "Tribe," along with marmots. "Ground squirrel" is a general name applied to species distributed through about six genera. The name "Rock Squirrel," however, usually just applies to our Spermophilus variegatus, so that's why I capitalize Rock Squirrel, but not ground squirrel.
It'd been a while since I'd wandered much in Jalpan Valley so last weekend I strapped on my backpack and did a two-day hike circling the reservoir. Instead of sticking to the road and known trails I followed cow, burro and wildlife trails, with the consequence that I got lost several times and ended up crashing through a great deal of spiny scrub. As so often happens after strenuous hikes the most memorable discovery turned up close to home, only about 40 feet from my casita. You can see what I found there at http://www.backyardnature.net/n/07/070727wf.jpg.
That strange object is a fungus about the size of a baseball. Note the glistening, greenish-brown, very stinky, pasty goo inside the pores. That stuff's stench attracts insects such as flies who wander into the pores looking for putrefying flesh, mellowing manure and the like. The gunk gets on the insects' legs, they fly away and spread it on whatever they land on. That's good for the fungus since the slime has spores in it, and those spores can germinate to produce new fungi.
The fungus is CLATHRUS CRISPUS, and if it has an accepted English name I can't find it. In the US it occurs in Florida and along the Gulf Coast, but mostly it's found in Mexico and the Caribbean. The species belongs to the fungus family Phallaceae, that name based on the obvious English root. Longtime readers of this Newsletter may remember my January 27, 2002 issue where I reported on finding a stinkhorn in Mississippi. Country folks back there were liable to call the slender, pointed, red stinkhorn a Dog-pecker Mushroom, because that's what it looked like, and it smelled like this week's Clathrus crispus. Several other outlandish-looking stinkhorn species exist and you might enjoy browsing "The Stinkhorn Hall of Fame" at http://www.mushroomexpert.com/stinkhorn_fame.html.
About a dozen of this week's stinkers grew in a heavily shaded patch of scrub across the fence from my casita. I suspect that the reason the fungus grew there so gregariously but not anyplace else I visited during my hike is that sometimes folks from the shantytown next to the reservoir take craps there. Clathrus crispus is "saprobic," which means that it derives its nourishment from nonliving or decaying organic matter. Old crap that's worked its way into the soil must look pretty good to it.
Flies aren't the only critters attracted to the species' stench, as you can see at http://www.backyardnature.net/n/07/070727wg.jpg.
SATELLITE SPHINX MOTH CATERPILLAR
I can't identify the lepidopteron in the above picture, but the moment I saw the caterpillar shown in the following shot I figured I knew what it was related to: http://www.backyardnature.net/n/07/070727ss.jpg.
That larva's finger-length size, thickness and side markings reminded me a lot of the hornworms that used to populate my tomatoes back in Mississippi, despite it bearing no "horn." Hornworms are the caterpillars of sphinx moths so on the Internet I searched for sphinx moth caterpillars. The caterpillar in the above picture turned out to be the larva of the Satellite Sphinx Moth, EUMORPHA SATELLITIA. You can see the moth and more images of the caterpillar at http://www.silkmoths.bizland.com/esatesat.htm.
If the moth picture at the above page looks like a hummingbird moth to you, that's OK, since moths of this family, the Sphingidae, are variously known not only as sphinx moths but also hawk moths and hummingbird moths.
At the above website you can see that younger caterpillars -- early "instars" -- possess a spiny "horn" just like the hornworms on my tomatoes. The spine doesn't appear on the last instar, however.
An odd feature of the caterpillar in the picture is its flat-looking head. Actually the larva has a normal, rounded head, but when the larva is disturbed or resting it can withdraw its first three or so segments into its body, like a collapsing telescope.
Satellite Sphinx Moths are distributed from the US border into South America, as well as the Caribbean. The caterpillars are known to eat viny members of the Grape Family. At night female moths emit a "pheromone plume" which males detect and follow to its source. A pheromone is a chemical that triggers an innate behavioral response in another member of the same species, in this case sexual activity.
It's interesting how when you're in a far-away, exotic area you keep meeting "variations on themes" you first learned about in your own home area. I'd never seen a Satellite Sphinx Moth caterpillar before last weekend, but the moment it appeared before me I already knew a lot about it, thanks to my tomato hornworm days in Mississippi.
DIFFERENCES BETWEEN FROGS & TOADS
During last weekend's slope-wanderings I ran across a very handsome Gulf Coast Toad whom you can admire at http://www.backyardnature.net/n/07/070727gc.jpg.
So, what's the difference between a toad and a frog?
In general, uncritical English, a frog is simply "a tailless, aquatic, semiaquatic, or terrestrial amphibian." Thing is, toads fit that description as well as what we think of as frogs. In fact, there's nothing against considering a toad a kind of frog.
Still, we think of frogs as having smooth to slimy skin, strong legs adapted for hopping, and as laying eggs in clusters. We think of toads as having dry, warty skin, paratoid (poison) glands behind the eyes, stubby bodies with short legs better for lunging than hopping, and as laying eggs in chains, not clusters.
But, there are warty-skinned frogs and slimy toads, and in certain froggy families there are species it'd be hard to say whether they look more like frogs or toads.
Taxonomy doesn't always help. When we think "frog," usually we visualize members of the True Frog Family, the Ranidae. This family, however, doesn't include species in over 30 other froggy families, such as those in the Treefrog Family and lesser-known frog families such as the Dart-poison Frog Family, the African Reed Frog Family, etc.
It's the same deal with toads. "True Toads," members of the Bufonidae, don't include members in families such as the Spadefoot Toad Family, the Firebellied Toad Family and others.
Really, if we want to be precise about our frogs and toads we need to use scientific names. Our Gulf Coast Toad is BUFO VALLICEPS of the True Toad Family, the Bufonidae.
THE PAPAYA BERRY
This week I bought a small papaya. While I had it split open I took a picture of it, which you can see at http://www.backyardnature.net/n/07/070727pp.jpg.
A lot of people are surprised that papayas are hollow inside, and that many soft, blackish seeds are attached to the cavity's walls by short, slender, stringlike umbilici. The attachment is so weak that a quick brush with a finger dislodges them. The seeds themselves are so soft that they can be chewed, but they have such a strong peppery taste, like wild cress, that few people bother with them.
As with the slippery terms "frog" and "toad," terminology relevant to papaya fruits also can be a bit disorienting. For example, botanically, papayas are berries. Technically, a berry is a pulpy fruit developing from a single pistil, containing one or more seeds but no true stone.
Therefore, the term "berry" is much more inclusive than we usually think. Tomatoes are berries, as are oranges, grapes and cucumbers. The concept of "berry" is so general that subcategories have beene defined. Cucumbers, like watermelons -- developed from inferior ovaries so that the resulting fruit is surrounded by a fleshy layer such as the watermelon's rind -- are berries of the "pepo" subcategory. Oranges are specialized berries known as hesperidia. A hesperidium possesses a thickened, leathery rind and juicy pulp divided into segments, the segments corresponding to carpels, or sections, in the original flower's ovary.
If flower terms like "carpel" and "inferior ovary" throw you for a loop you may want to review my flower page at http://www.backyardnature.net/fl_stand.htm.
An overview of fruit types is provided at http://www.backyardnature.net/fruits.htm.
I want to be sure you know what dayflowers are, for they're elegant little beings with unusual floral anatomy, and in much of North America, as well as here along weedy roads, they're blossoming now. Four dayflower species are listed for the Reserve; six are described in the Flora of the Carolinas.
Dayflowers are species of the genus Commelina. The one flowering along our weedy roadsides now is COMMELINA ERECTA, sometimes called the Whitemouth Dayflower. See it at http://www.backyardnature.net/n/07/070727cm.jpg.
The blossoms in the above picture hold two large petals above their sexual parts, like white fans. A handlens reveals a third tiny, white petal just below the ovary, and that petal is what gives the plant its Whitemouth name. The top two petals of most members of this species are blue, but around here ours are white, which sometimes happens.
Dayflower blossoms have 3 sepals, 3 petals, 6 stamens of which only 3 are fertile, and the fruits usually are 3-celled capsules. The flower parts being in threes and multiples of three makes sense since dayflowers are monocots, thus closer to lilies and grasses than to dicot daisies and oaks. Dicot flower parts usually appear in fours, fives, or multiples thereof.
One unusual feature of dayflower blossoms is that the three infertile stamens, called staminodes, are yellow, as well as the middle one of the three fertile stamens. In the picture the yellow items are the staminodes and the middle fertile stamen, all held a bit above the ovary. Also you can see the pale two fertile stamens held below the ovary. Surely the splotch of yellow attracts pollinators and the position of the two fertile stamens assures that pollinators get dusted with pollen.
Another unusual feature of dayflower blossoms is that they arise from flower-size, green, leaflike bracts folded down the middle to form something like barely open, flattish clamshells. You can see the bract very clearly beneath the flower on the right in the picture. These bracts protect the delicate blossoms in the bud stage. And, delicate the blossoms are, as the name "dayflower" suggests -- the flowers supposedly lasting only a day before vanishing.
The plants themselves, however, are tougher. Our Whitemouth species is robust enough to inhabit a large distribution area, occurring across much of the US, and south through Mexico into Central America.
Dayflowers belong to the Spiderwort Family, the Commelinaceae.
ALAMO VINE ALONG THE FENCE
Back in the dry season they were just brown, dead- looking vines entangled in the chain-link fence along the road to the reservoir, but even then I could see that the vine was something different from normal morning-glories. For, the fruit-capsules were big yet produced only four or fewer seeds per capsule. Also, the split-open fruits looked like silver-dollar-size, woody stars, something I'd not seen.
When the flowers came with the rainy season they looked like morning-glory flowers, except that their pollen-producing anthers were strongly twisted. Moreover, the vine produced Virginia-creeper-like leaves instead of the usual heartshaped morning-glory leaves. You can see a flower, leaf and unopened flower-bud at http://www.backyardnature.net/n/07/070727md.jpg.
The vine is MERREMIA DISSECTA, sometimes in English called Alamo Vine, and sometimes, because of those star-shaped, woody, split-capsule remains, Woodrose. It's a genuine member of the Morning Glory Family but in a genus we don't hear much of. Many Merremias produce yellow flowers, despite our Alamo Vine's white ones.
The vine is distributed from the southern US through Mexico to northern South America, and the Caribbean.
CAMPING WITH OCTAVIO PAZ
On my hike around the reservoir last weekend I carried a copy of Octavio Paz's ITINERARIO. Paz, who died in 1998, was a Mexican Nobel Prize winning writer. It was hot and humid last Saturday so every now and then during my hike I'd find a shady spot with a good view, pull Paz's book from my backpack, and read awhile. At dusk, inside my tent atop an isolated peak with White- winged Doves cooing around me, treefrogs plinking and thunder booming across the next ridge, I read Paz then, too.
It's a shame Paz didn't know more about Nature. His world was human thought, human politics and human history. As such he restricted himself to just a tiny, tiny corner of the Universe.
What fascinates me is that despite this limitation Paz developed profound insights, and a belief system I'm more or less comfortable with. This doesn't surprise me, though. Often I've observed that all complex systems, be they biological ecosystems, mature political beliefs, the evolving Universe, or whatever, are pretty much structured the same. Study anything in very great detail and you gain insights applicable far beyond the field you're studying.
For example, Paz ends ITINERARIO with "The Universe is innocent, even when a continent sinks or a galaxy cinderizes." The concept of "bad" lies in human minds, he says. He sums up his insight by saying that "to fight against evil is to fight against ourselves."
What a hoot that Octavio Paz, prize-winningly working out the structure of the human condition by examining human thought, politics and history, comes to the very conclusion I did for what's needed for "saving Life on Earth."
For, if humanity is to save Life on Earth, we must do battle with our own appetites, our own lack of empathy with other living things, our own insensitiveness, our own unsustainable traditions (especially inherited systems of thought such as religions and blind nationalism), and our deep-seated aversions -- in a rapidly changing Universe -- to change.
I think it's pretty neat that Octavio Paz, studying human thought, politics and history, came up with the same conclusion I did looking at oak trees, ants and quartz crystals.
Best wishes to all Newsletter subscribers,