November 11, 2012
ARMADILLO AT DUSK
Critters have their routines, and lately a certain armadillo has been wandering onto the road we walk at dusk at pretty much the same time each night. Experience suggests that he may do this for a week or two, then disappear, presumably changing to a different route. It's getting dark by the time this armadillo comes out but one night I did get a picture of him as he skittered off the road into the bushes, stopped, and squinted back at me, as you can see in a grainy, low-light photo at http://www.backyardnature.net/n/12/121111ar.jpg.
A couple of days after that picture was taken, across the river we came upon a roadkill armadillo, so we were able to get a better look at what makes an armadillo an armadillo. For example, can you imagine what you're seeing at http://www.backyardnature.net/n/12/121111as.jpg.
Those are the bony scales or plates covering most of the armadillo's top. You're seeing small sections of two of the bands of the Nine-banded Armadillo, DASYPUS NOVECINCTUS, which is the armadillo species we have here. About 10 armadillo genera and 20 species have been described, with other species known as fossils. Armadillo species occur mostly in South and Central America.
The armadillo's underparts aren't covered with plates, as a close-up shows at http://www.backyardnature.net/n/12/121111au.jpg.
At the bottom of that picture you see the edge of the armadillo's banded, plated top shell. Above that edge is the armadillo's hairy, unprotected belly.
At http://www.backyardnature.net/n/12/121111at.jpg you see the undersurfaces of two of the armadillo's feet. At the left the back paw bears five distinct toes and thick calluses, while, at the right, the narrower front foot has only four toes. If you've ever picked up an upset armadillo you might know that you don't have to worry about being bitten, because armadillo teeth are just low, rounded peglike affairs. However, the armadillo's legs are powerful, can scratch at you furiously, and those toenails are hard as bone.
GIANT CRAB SPIDER
I was painting the outside of a house when my painting buddy let out a yelp followed by a "You have to come see this." The thing to be seen is shown at http://www.backyardnature.net/n/12/121111s8.jpg.
My painting buddy had been running his finger below some weatherboarding to clean it out, and that spider had skittered from his shelter onto the glass window. It was a very big, hairy one, about the size of a small tarantula and nearly as hairy, but something about it didn't look like a tarantula, despite its two-inch (5cm) leg span. You can see what seemed most unlike a tarantula to me at http://www.backyardnature.net/n/12/121111s9.jpg.
It's the eyes. All the tarantulas I've seen have their eight tiny eyes clustered closely together in front, but this window-perching spider's eyes are fairly large and spread across a wide "face."
By the way, in that picture the eyes appear above the horizontal band across the "face." The large, black items pointed downward are the chelicerae, which are mouthparts, at the bottom of which arise the fangs, which are tapering, curved needlelike affairs with which venom is injected into the spider's prey.
Volunteer identifier Bea in Ontario figured out this unusual spider pretty fast. It's the Giant Crab Spider, OLIOS GIGANTEUS. Just last week in our Newsletter we looked at a more typical crab spider, the Ground Crab Spider, which you can compare at http://www.backyardnature.net/n/a/xysticus.htm.
Besides both spiders being found on the walls of the same old house in Texas, other similarities confirm their crab-spiderness, including the manner in which they spread wide their legs, move sideways so easily, and construct no webs. Of the more than 2000 crab spider species in the world, the Giant Crab is one of the very largest. I've read that its bite can be a little painful, but it's not dangerous to humans.
As is typical for crab spiders, the Giant Crab hunts for small prey, mostly on the ground and it prefers to hunt at night. In Spanish its name is Cazadora del Desierto, or Desert Hunter. In fact, the Giant Crab mainly occurs in arid northern Mexico, extending into the US only from southern California up to Nevada and over here to southwestern Texas.
One other feature of Giant Crab Spiders setting them apart from their congeners is the ease -- despite their large size -- with which they climb smooth, vertical surfaces. How that big spider stuck to the window of the house we were painting I just can't say.
LOUNGING HOUSE SPARROWS
We have House Sparrows here, sometimes called English Sparrows. They're PASSER DOMESTICUS, introduced from Europe, and now they're spread throughout most of North, Central and South America. Despite their enormous distribution, I was a little surprised to find them here. At my bases in Mississippi I didn't see them because there I lived mostly surrounded by forest, and House Sparrows can't compete with native species in such woodsy environments.
However, here in the valley of the little Dry Frio River the valley floor is mostly occupied by ranchland where livestock knock grain from feed troughs and seeds pass through guts and end up in cow paddies filled with undigested grain, thus providing House Sparrows with food. And there are barns, sheds, outbuildings and homes with all kinds of corners in which House Sparrows love to build nests.
So, on chilly mornings here before the hot afternoons roll around, it's common to see House Sparrows sunning themselves, their bodies turned to receive maximum exposure to the warming morning sunlight. They're not as nervous about nearby humans as other bird species. You can see one who likes to sun himself each morning in a certain spot behind the cabin at http://www.backyardnature.net/n/12/121111hs.jpg .
Actually, I don't think that bird ever uses the nesting box just below him. It's hole is too small, I think -- probably purposefully made that way just to keep House Sparrows out. That nesting box is meant for native bluebirds and wrens. Lots of people don't like House Sparrows, thinking of them as little more than invasive, flying mice.
I rather like House Sparrows, however. Back in the 70s when I lived in Nashville, Tennessee I wrote a book on "One Year in the Life of a House Sparrow," and by the end of that book I was feeling empathy with the House Sparrows I found begging for breadcrumbs in the park and hanging around sloppy back alleys. You might enjoy that book. It's online at http://www.backyardnature.net/sparrow.htm, and you can download the book in various formats at http://www.backyardnature.net/j/books/index.htm#yellow.
The book is about a female House Sparrow, but the bird in our picture is a male. You can have a better look at him at http://www.backyardnature.net/n/12/121111ht.jpg.
You know he's a male because of the black speckles below his chin and on his chest. Mature males during the breeding season are starkly black in these areas, plus their bills and the area around their eyes are all black. However, after molting in the fall, their winter plumage is more or less what you see in that picture. I suspect that our shed-sitter is an immature male, perched there contemplating his very first season of autumnal sun-basking.
Readers who followed me while I was in Mexico know that in my various gardens I've had trouble with leafcutter ants -- large tropical ants that can turn a garden or small tree into tatters overnight. Our page for Mexican leafcutters is at http://www.backyardnature.net/mexnat/leaf-cut.htm.
One of my biggest surprises when I arrived here in southwestern Texas is that leafcutter ants also are found here. Already during my first week of gardening here I became acquainted with our Texas leafcutters because each night they formed a busy column passing through the center of my fenced-in, raised-bed garden area, to get to the big Chinaberry tree at the corner, which they were methodically defoliating. They didn't bother my raised beds, however, so I let them be -- until the day I found scouts wandering through my bed of mustard greens looking very interested.
Then I did what the Maya taught me to do: I sprayed a very light but smelly application of diesel fuel around the bases of the beds. The scouts immediately disappeared and the line through the garden, which previously had run alongside a couple of beds, was changed to run between them. This peaceful but unsteady state of coexistence was maintained until one morning this week when in my other, on-the-ground garden I found what's shown at http://www.backyardnature.net/n/12/121111ld.jpg.
Those are beet leaves cut from their dark purple stems as neatly as if snipped off with scissors. My entire beet planting was like that, with wilting leaves lying on the ground. Leading away from my beet bed was a line of large, orangish ants, most of them carrying cut-out tatters of beet leaves, as shown at http://www.backyardnature.net/n/12/121111lc.jpg.
A close-up of a single ant carrying its beet-leaf umbrella is at http://www.backyardnature.net/n/12/121111le.jpg.
I sprayed a light application of diesel along the side of the garden between my plants and the ants' nest, and so far they have not returned.
Apparently there's only one leafcutter ant species in Texas, and that's the Texas Leafcutting Ant, ATTA TEXANA, distributed in southern and eastern Texas, western Louisiana, and in Mexico in the arid northeastern states and along the Gulf of Mexico as far south as Tabasco state.
By the way, now a map is available enabling us to see which Mexican leafcutter ant species are found where. Now we know that in the Yucatan I was experiencing Atta cephalotes, while in Querétaro and Chiapas we had Atta mexicana. Now with the so-called Texas Leafcutting Ant, we have known all three species of Mexican leafcutter ant. The map is at http://www.blueboard.com/leafcutters/distribution/images/mexico_attas_distribution.jpg.
In the last Newsletter we saw how Big Bluestem Grass forms extensive carpets of single-species grassland in pastures occupying the flat floodplain of the Dry Frio River Valley, as well as the "lawn" around the cabin in which I live. Big Bluestem's profile page is at http://www.backyardnature.net/n/h/bigblue.htm.
At the very base of the limestone hills framing the valley, exactly where the flat floodplain and its big pastures meet the hills' lowest slope, and short, fairly open forests of Ashe Juniper and Texas Live Oak begin, Big Bluestem disappears and another taller, yard-high (1m) grass takes its place. Nowadays this taller grass is flowering as its long, breeze-bent leaves take on a slight blush of rusty coloring, shown at http://www.backyardnature.net/n/12/121111an.jpg.
This grass's flowering heads are fairly open and not so bushy, as shown at http://www.backyardnature.net/n/12/121111ao.jpg.
This grass is Little Bluestem, SCHIZACHYRIUM SCOPARIUM, one of the "Big Four" grass species mentioned last week as constituting the main grass species of the vast grasslands or prairies that once occupied much of central North America. If only because of its abundance, historically it has been of enormous ecological value, being a prime food source for grazing animals such as Bison and deer. It has protected vast stretches of land from erosion, its tough, slender, narrow leaves still serve as excellent nesting material for many species of birds and rodents, and its seeds are a major food source for many small birds. Its abundance places it at the foundation of the mid-continent natural grassland ecological pyramid. Little Bluestem is simply one of the most important flowering plants on Earth.
By the way, it's interesting that -- at least in our valley -- Little Bluestem averages about twice the height of the Big Bluestem we looked at last week. In many other areas it's the other way around.
In the above picture you saw that the heads are somewhat narrow, like gnawed-on toothpicks with very frayed tips. That's what the fruiting heads look like most of the time, but if you visit the grass in late afternoon on a hot, dry day, you'll see that the heads have opened up, exposing the ultimate inflorescence branches to the wind. The grass's parachuted, achene-type fruits are wind disseminated. The sun-dried, curvy inflorescence branches are distinctive, and elegant, as shown at http://www.backyardnature.net/n/12/121111aq.jpg.
These fruiting heads are so unlike those of more commonly encountered species that a little effort may be required to understand what we're seeing. A close-up of one of the above ultimate inflorescence branches is shown at http://www.backyardnature.net/n/12/121111ap.jpg.
Remember that we explain basic grass-flower anatomy terms at http://www.backyardnature.net/fl_grass.htm.
That picture shows the tip of an ultimate inflorescence branch consisting of three connected "paired spikelets." The paired spikelets are technically referred to as rames. At maturity the inflorescence branch breaks up, or disarticulates, so that each rame is carried off by the wind separately. Notice that the top rame looks a little like a slender bird with its narrow wings open, or maybe it's like a fleur de lis symbol. That top rame's bottom is connected to one of the "wings" of the second-from-top rame, and that that rame's base unites with one of the "wings" of the third-from-top rame. On and on it goes all the way down the whole inflorescence branch.
When the top rame is carried off by the wind, the second-from-top rame will look like the top rame now looks, like a flying bird. However, now we know that one of its wings actually is the fuzzy base of what was once the topmost rame. Thus one "wing" of the rame is actually the inflorescence stem, or rachis. So, what's the other "wing?"
The other "wing" is the rame's second spikelet. Each rame consists of a large spikelet without a flower stem, or pedicle, and a second smaller spikelet on a slender pedicle. The large spikelet produces an achene-type fruit, but the smaller spikelet on its pedicle is sterile. Seeing the hairs on this second, sterile spikelet, we can surmise that its main function is to serve as a "wing," to help in wind dissemination.
SHRUBBY BLUE SAGE
Last week we looked at the famous Scarlet Sage, a beautiful, conspicuous, and fairly common wildflower found in rocky places here, especially on the slopes of our forested limestone hills. This week we have another sage -- another member of the Mint-Family genus Salvia -- but this one I've found only in thin, dry soil at or near the top of our limestone hills. Unlike the ground-hugging, herbaceous Scarlet Sage, this sage is a head-high, fairly woody, densely branched shrub. Its leaves are typical of the sages in terms of shape and spicy smell when crushed, but the leaves are especially small, and the flowers are tiny and inconspicuous compared to the Scarlet cousin. At first glance you don't want to believe this shrub is a sage. However, such variation is to be expected among the sages, for the sage genus, Salvia, is the largest genus in the Mint Family. It's estimated to embrace 700 to 1000 species.
You can see a flowering branch of our blue-flowered, hilltop sage at http://www.backyardnature.net/n/12/121111s2.jpg.
One name for this shrub is Shrubby Blue Sage, though it seems that most often even English speakers use its Spanish name, which is Mejorana. It's SALVIA BALLOTIFLORA, distributed mostly in Mexico's arid northeastern states where limestone outcrops as the bedrock. It is especially common in limestone canyons. In the US it extends up through southern Texas to about here, the limestone outcroppings of the Edwards Plateau in southwestern Texas.
Structurally, Shrubby Blue Sage's flowers are definitely sage flowers -- bilateral symmetry with distinct upper and lower lips, stamens inserted on the corolla throat with only the lower pair producing pollen. A close-up of the half-inch-long (13mm) flowers is at http://www.backyardnature.net/n/12/121111s3.jpg.
Besides being invested with long, soft hairs and many glands, a distinguishing feature of the flowers is their oversize calyx -- the pale green, funnel-shaped item at the left in the above picture, from which the blue corolla emerges. You may have noticed in the first picture that after pollination, when the corolla has fallen off, the calices expand even much larger. I would guess that this is to facilitate wind dissemination of the tiny nutlets inside the calices.
As soon as you smell Shrubby Blue Sage's spicy leaves you can believe the written reports that formerly the leaves were used for flavoring meats and other foods, and that a reasonably acceptable tea might be made from the leaves. If you stand beside the bush you see small pollinators of various kinds coming and going.
The day back in August when I arrived here I found the raised beds in the abandoned garden area absolutely overgrown with weeds. One bed was solidly choked with one waist-high weed species, which also grew all around it, almost hiding the bed. I cleared it all out except for a small patch in the corner, which I kept for diversity's sake, and because I like tough things, like this weed, plus it's kind of an interesting species, and if you look at it closely you can see neat things. You can see what it looks like now in mid November, a bit ragged occupying a corner defined by deer fencing, at http://www.backyardnature.net/n/12/121111aa.jpg.
This is Common Ragweed, AMBROSIA ARTEMISIIFOLIA, the very one so famous for causing hay fever with the pollen they issue from those slender flowering heads atop the plant in the picture. A closer look at a pagoda-like flowering head, which is a raceme-type inflorescence, and the plant's deeply divided leaves, is seen at http://www.backyardnature.net/n/12/121111ab.jpg.
The pagoda-like racemes consist almost entirely of tiny clusters of male flowers, maybe with just three or four female flowers at the racemes' bases. A close-up of two clusters of male flowers, with an inset showing a male flower's corolla removed from a cluster, is at http://www.backyardnature.net/n/12/121111ac.jpg.
That's a metric ruler next to the corolla showing two marks designating the length of one millimeter. Therefore the corolla is one millimeter long, or about 1/32nd of an inch. Ragweeds are members of the Composite, or Sunflower, Family, so that explains why several flowers are packed together into a bowl-like structure known as the involucre. You can see that the involucre is covered with many short, sharp, broad-based, forward projecting hairs, and that the green surface is granular, presumably with glands filled with aromatic oils. That would explain why, if you crush a Common Ragweed's leaves between your fingers, you get a pleasant, spicy odor.
So, those are the male flowers, and if you look very closely at a raceme's base you'll find some female flowers, but you have to know what you're looking for if you're to recognize what you see. Some female flowers are shown at http://www.backyardnature.net/n/12/121111ad.jpg.
In that picture's lower, left corner the dark, hairy, spherical item with slender, string-like things -- they're styles -- arising from the top, is the flower's future fruit, which will be a kind of bur with spines or tubercles. Common Ragweed's female flowers lack corollas.
Common Ragweeds are native to North America but have spread as weeds into Europe, Japan and other places.
Back on the farm in Kentucky this species reduced our soybean crops a good bit. Now it's known that night tillage of land on which Common Ragweed has deposited its seeds reduces emergence of the plant the following year by around 45%. Night tillage is exactly that -- tilling at night. Light is needed to break the dormancy of Common Ragweed's seed, so if fewer seeds are exposed to light during the tilling process, fewer will germinate.
At http://www.backyardnature.net/n/12/121111sx.jpg you see a semi-woody vine that's fairly common in these parts, especially at weedy woods edges and along roads. Notice the leaves' distinctive shape, with broadly lobed bases and pinched-in sides, and their shininess. Also note the clusters of black, grapelike fruits suspended above the vine's main stem. They're so black they almost disappear against the shadowy background. A closer look at a fruit cluster is at http://www.backyardnature.net/n/12/121111sz.jpg.
In that picture also notice the short, broad-based spines along the stem. Though the berry-type fruits are only about 5/16ths inch across (7mm) they look good enough to eat. However, if you bite into one you find very little flesh at all, nearly the entire berry being occupied by a hard seed, as shown at http://www.backyardnature.net/n/12/121111sy.jpg.
Probably you're familiar with this kind of spiny vine, but what you call it may depend on which section of the country you live in, or which field guide you learned its name from. Maybe the most common English name for the plant group -- the genus Smilax -- is greenbriar, though it's also called catbrier, sawbriar, sarsaparilla, and other names. The species in our pictures is SMILAX BONA-NOX, in this area apparently usually called Saw Greenbrier, but in other places it's known as Bullbrier, Chinabrier, Tramp's Trouble and by other names. The "bona-nox" species name means "good night" in classical Latin. It's unclear why Linnaeus, who named the plant in 1753, gave it this name. The page editor for the species at the Duke University website suggests that "bona-nox" might have been a Latin curse, something said when one scrapes unprotected ankles along this spiny species' stems.
I grew up with Smilax bona-nox in the western Kentucky countryside and it grew all around my hermit camp in Mississippi, so it's bloodied my ankles many times. The species' distribution is mainly the US Southeast, extending as far north as southern New Jersey and central Missouri. Here in southwestern Texas we're about at its western extreme of distribution, though it continues much farther south into eastern Mexico.
Around here the fruits of Smilax bona-nox are eaten by Wild Turkeys, Opossums, Raccoons, squirrels, and many species of songbirds. White-tailed deer browse the foliage.
FEATURED ESSAYS FROM THE PAST:
"Bird Flocks, Breast Milk & Trust," from the August 23, 2009 Newsletter, at http://www.backyardnature.net/n/p/090823.htm.
"Bird Therapy" from the November 15, 2005 Newsletter, at http://www.backyardnature.net/n/p/051115.htm.
Best wishes to all Newsletter readers,
All previous Newsletters are archived at http://www.backyardnature.net/n/.
Even without a Facebook account you may be able to access an index to this week's essays, with each essay on its own page and with images embedded in the text, on the Facebook page at http://www.facebook.com/pages/Jim-Conrads-Naturalist-Newsletter/412345652126940.
Visit Jim's backyard nature site at http://www.backyardnature.net