May 26, 2007
INDIGO AT MY KNEE
Above a cliff of outcropping limestone next to the lake I was hiking an overgrown cattle trail through scrub paying more attention to keeping my balance on the steep slope than anything. Then I saw it: Not a yard from my leg rose the front end of a massive, blue-gray snake between six and seven feet long, his head hooked forward and pointed at my right knee. My first thought was, "Well, I've been looking for you for a long time!"
For, it was an old friend. Back in the early 70s when I was a graduate student at the University of Kentucky one of my favorite teachers, Dr. Roger Barbour, used to keep one of these giants he'd picked up in Florida on the top floor of the tower of the Funkhauser Building, which at that time hosted most biology classes. Often I'd visit the snake and the nice lady who cared for Dr. Barbour's critters. The snake was one of the most gentle, agreeable animals I've ever met, and the lady was nice, too. I developed very pleasant associations with this species.
It was an Indigo Snake, DRYMARCHON CORAIS, North America's longest snake, the record being 103.5 inches (262.8 cm, over 8.6 feet). In the US the species occurs in Florida and Georgia, with old records placing it in other states as well, but those populations appear to have been wiped out because of habitat destruction and intentional killing. As the species is understood now, it's distributed south to Brazil. There's talk about separating populations found west of the Mississippi River, which includes ours, into the species D. melanurus.
By the time I'd pulled off my backpack (I'd camped overnight in the area) and got my camera set up, the Indigo had slipped over the cliff. However, just a few feet away I found a shed skin, which I photographed next to my 12.5-inch long sandal for scale. You can see that image at http://www.backyardnature.net/n/07/070526is.jpg.
You can see somebody else's Indigo Snake at http://www.hoglezoo.org/animals/view.php?id=58.
Back at the casita I looked up the Indigo in Jonathan Campbell's herp book which previously I used in the Yucatan. It said that Indigos in the southern US have "... a reputation for being docile and mild-mannered. This is not true of tropical indigos, which are easily irritated to the point of inflating the throat and vibrating the tail, and often delivering a powerful, although nonvenomous, bite." I got a twang in my right knee when I read that.
In the US, Indigos are listed in the US Federal Register as threatened.
AND A SPECKLED RACER, TO BOOT!
I suppose it took last week's bemoaning my having seen so few snakes in this area to change things, but the fact is that not 50 feet from the Indigo Snake I ran into another species whose picture can be seen at http://www.backyardnature.net/n/07/070526sr.jpg.
This black, heavily speckled, very slender, three-ft- long snake was a Speckled Racer, DRYMOBIUS MARGARITIFERUS, distributed from southern Texas (listed as threatened) through Mexico and Central America into Columbia. Over much of its distribution it's known as Ranera, which means frog hunter, and it's true that its main food is frogs and toads, though it'll also eat lizards, small snakes and other small critters. It has no venom and instead of killing its prey by constriction swallows it alive.
I think the reason the racer didn't race away as once again I pulled off my backpack, retrieved my camera and waited for the camera's setup procedures to whirr and blink into place was this: True to its Ranera name, upon my approach the snake had disgorged a half-dead frog, thus making it easier to slip away if I proved threatening. Probably the snake just didn't want to abandon his meal.
After the picture was snapped he did move on, however, and so did I, hoping that by my leaving he'd return and finish his job. My experience with this species doesn't much coincide with the description on Wikipedia, which describes Speckled Racers as "fast moving, nervous snakes... "
My friend Pancho tells me that at about the same time I saw my racer, near his house in Jalpan, he saw seven Speckled Racers crossing a trail in a woodlot. There was one long one, maybe three feet in length, around which the other six stayed entangled as the long one moved. Pancho thought it was a mother with six young but it sounds to me like a female with six smaller males wanting to mate.
MILLIONS OF TADPOLES & TOADS
Up where the reservoir narrows between steep slopes and wet-season shallows now stand as Frogfruit-mantled terraces, you wouldn't believe the numbers of tadpoles. Well, you can get an idea from the picture at http://www.backyardnature.net/n/07/070526tp.jpg.
That image shows thousands of pea-sized tadpoles alongshore, and similar tadpole superfluity continued up and down the bank a long way. How on Earth could there be enough food for them to eat? I assumed the water was muddy because the previous afternoon cattle had been wading in it to keep cool, but maybe it was just kept churned up by tadpoles.
And maybe the overabundance of tadpoles explains the hoards of tiny toads swarming through the vegetation mantling the former mudflats, where there's a toad about every half foot. Most toads are pea-sized but some are half grown and at least two looked like adults. One adult jumped from my path leaving a silvery jet of pee in his wake and the other remained cozily in a big mud crack as I took the picture at http://www.backyardnature.net/n/07/070526tc.jpg.
The toad in the mud crack seems to be the Gulf Coast Toad, BUFO VALLICEPS, distributed from the US Gulf Coast through Mexico to Costa Rica. I can't be certain that the tadpoles and immature toads are the same species, but it's a good bet.
In fact, when I camped out last Saturday night near where the above photos were taken I was awakened in the night twice by sounds. First, a little shower came very pleasantly pecking on my tent roof around midnight and, second, not long afterwards, a placidly thunderous chorus of multitudinous toad-calls awoke me, sounding exactly like the Gulf Coast Toads heard in the .WAV audio file online (click on the words "Bufo_vali_M.WAV" at the "Link" link) found at http://www.biodiversity.bz/find/resource/profile.phtml?dcid=21999.
Near that same area the reservoir's main source stream cuts a narrow channel through a mudflat that most of the year is submerged. The channel's banks are steep and composed of loose, sandy alluvium. Here and there along the banks I found numerous recently excavated holes, or tunnels, about big enough to stick my little finger into. As I stood there trying to decide who was doing the digging, a large, stocky, amber-colored wasp landed at a tunnel's mouth, entered, and immediately began kicking dirt from the hole. Before long I'd seen several such wasps coming and going from holes, and some kicked out dirt.
Then a wasp landed carrying beneath her a cicada larger than herself, and in less than a second both wasp and cicada disappeared into a tunnel. During maybe five minutes I saw four such wasps carrying cicadas into tunnels, each cicada being carried belly-up, the victim's silvery-white ventral surface showing very conspicuously.
My digital camera needs to whirr and blink a bit before a picture is snapped so I never was fast enough to capture an image of a cicada being carried into a tunnel, but I did indeed photograph a wasp at a tunnel's entrance, and you can see that picture at http://www.backyardnature.net/n/07/070526ck.jpg.
The wasps were SPHECIUS CONVALLIS, sometimes known as Pacific Cicada Killers, even though here we're closer to the Gulf Coast than the Pacific. The cicadas being carried into the tunnels had been stunned by the wasps' stings, but not killed. The female cicada killer carries a paralyzed cicada into her burrow, deposits it in a nest cell, lays an egg on the cicada and seals the cell. When a grub hatches from the egg it eats the cicada, which meanwhile has not rotted because it has remained paralyzed but alive, and then...
Sphecius convallis's entire lifecycle isn't known. Eastern North America is home to a cicada-killer species similar to ours, and it's been studied, so we know that after that species' grub eats its cicada it overwinters underground in a hard cocoon. It pupates the next spring, metamorphoses from the puapa in July or August, digs its way to the surface and lives aboveground for up to six weeks. Its life aboveground as an adult, which accounts for less than 10% of its total life cycle, coincides with cicada emergence.
If our species has a similar lifecycle, then in a few weeks when the rainy season raises the reservoir's water level, all the nests I saw this week will be submerged for many weeks. Are the nests doomed, or are they sealed against the water? It's very unlikely that adults will emerge before the nests are flooded, for cicada killer lifecycles are coordinated with cicada emergences, and our cicada population already seems to be declining. I'm in contact with Dr. Chuck Holliday at Lafayette College in Pennsylvania, who has seen this species nesting in other sites prone to flooding, and who is excited about learning more about our population. Dr. Chuck's "Cicada Killer Page" is at http://ww2.lafayette.edu/~hollidac/cicadakillerhome.html.
If your computer is equipped with the QuickTime video player or you're willing to download the free QuickTime plug-in, check out video clips of various kinds of wasps filmed during important moments in their lifecycles. One video shows cicada killers mating and lugging cicadas. The page can be accessed at http://www.nhsvideo.com/wasps.html.
One thing certain about our cicada killers is that right now they have plenty of cicadas at hand. Cicadas have been calling here for about a month. At dusk, during the half hour of dim light preceding complete darkness, cicadas are so loud around my casita that one must stand near and speak loudly to be understood. Sometimes the sound tilts from "amazing" to "painful."
However, this week I've begun seeing lots of cicadas lying on the ground with their white bellies skyward, usually with a line of ants trailing from them, the ants hollowing out the cicada exoskeletons out. I suspect that our cicada peak has passed, and as the rainy season approaches dusk will start growing a little quieter.
Also at the far end of the reservoir several large, dead tree-snags rise from the water about 20 feet from shore. When the reservoir's water is high just a few feet of the black, half-decayed, ancient-looking trunks are exposed, but now the snags tower above the water like ravaged, Gothic castle towers. Plants not usually thought of as epiphytic grow on them as if they were islands.
I was approaching two such snags as a pair of Social Flycatchers made a fuss. You can see this species at http://www.greenbackedheron.com/photo/59215802.
Social Flycatchers are noisy critters with shrill, piercing, repetitive calls that get old quickly, CREEE, CREEE, CREEE, CREEE... That day, two birds perching near one another were shattering the morning's quietness every 30 seconds or so because each time either bird changed position or flitted to a nearby perch it issue that call. While the call was being issued, the bird would quiver its wings like a juvenile wanting to be fed. However, both birds did the call-quiver, so it didn't appear to be a feed-me signal, nor did it seem to be part of a courtship ritual. Trying to interpret what was going on I watched the pair for about fifteen minutes, but all I could figure out was that maybe they felt compelled to constantly report to one another about each little change in location or position they made, like kids text-messaging. They were being "social."
During my watch, a bird looking almost exactly like a Social Flycatcher but much larger made a beeline from the scrub alongshore to a heap of straw untidily wedged into the angle formed by a cactus growing on the neighboring water-surrounded snag. This new bird quickly vanished into a hole in the side of the straw-heap. It was a Great Kiskadee entering her roofed straw nest. Kiskadees also are flycatchers but in a different genus from Social Flycatchers. It's something how they, being about 9.5 inches long, look so much like Social Flycatchers, who are only about 7 inches long. You can compare the above image of a Social Flycatcher with one of a Great Kiskadee at http://fireflyforest.net/firefly/2006/06/26/great-kiskadee/.
Great Kiskadees are also known for their loud, raucous calls -- kis-k-DEE, kis-k-DEE, kis-k-DEE, but that morning this bird erupted only once. Moreover, this kiskadee did a very unkiskadee thing: After making a few trips across the water to the nest it flew onto a bare, wet mudflat and hopped about pecking at things, possibly the aforementioned baby toads. My photo of the kiskadee's roofed nest is at http://www.backyardnature.net/n/07/070526kn.jpg.
Meanwhile, yet a third flycatcher species came onto the scene, this one not making a peep and behaving very secretly, after some skulking and hesitating vanishing into what looked like an abandoned woodpecker hole in the old snag the Social Flycatchers were cavorting on. It was a Sulphur-bellied Flycatcher, whose bright, rusty tail was much more eye-catching than any theoretical sulphury belly. You can see the species at http://www.rshantz.com/Animals/Birds/Flycatchers/Sulphur/20040726Sulphur01.htm
These old, rotting snags, so unsightly to some people, sure are important citizens of the congenial ecosystem at the far end of the reservoir. Dead tree-snags are wonderful things.
ANOLE AT DAWN
Exactly when it had grown light enough to see the vegetation around my tent a slender lizard darted onto a bush stem running horizontally at arm distance right before my eyes. The critter froze there for several minutes, appearing to look at me as if trying to understand what I was doing sitting cross-legged in a tent's door at daybreak. Happily, I was able to get to the camera and snap the picture you can see at http://www.backyardnature.net/n/07/070526an.jpg.
In the dim early-morning light I wasn't able to make much out about the lizard, but once the picture had been downloaded onto my computer's screen it was clear that I'd been visited by a Silky Anole, ANOLIS SERICEUS, occasionally placed into the genus Norops. This is the closest species we have here to the Green Anoles, or "Chameleons," who used to hang on my trailer walls back in Mississippi.
Like my Green Anoles, adult Silky Anoles possess colorful dewlaps they can unfurl beneath their chins when displaying. My twig-sitter was hiding his dewlap but you can see another one with his fan unfurled at http://www.fortunecity.com/greenfield/drongo/177/sericeuspvb05002.JPG.
This species is widely distributed from northern Mexico to Costa Rica and occurs in many habitats, from tropical wet forest to dry, open areas. It also exhibits several color and pattern variations, so taxonomists sometimes refer to the "Anolis sericeus complex," hinting that splitters may want to divide it into several distinct species, but lumpers are keeping it all together for the moment.
I read that over the course of the rainy season the female produces several nests, or clutches, in which she deposits a single egg.
THE SUN OVERHEAD
One day this week a bit after noon I saw that my solar oven wasn't cooking as effectively as it usually does. I glanced upward, expecting maybe to see haze between us and the sun, and I was surprised by what I saw: The sun, in a cloudless sky, was almost exactly above me. My oven's reflectors are designed to focus sunrays slanting in at an angle, so when the sun is directly overhead the system doesn't work...
So, of course! This summer I'm south of the Tropic of Cancer, so naturally as the sun's daily path, its ecliptic, migrates northward toward the Tropic of Cancer -- exactly above which it'll stand on the date of the Summer Solstice, June 21 -- at some point the ecliptic has to pass directly above us.
But, it wasn't exactly overhead that day. It still lay a little south of overhead. Therefore, the question: On what date will the sun, at midday, be as close to possible directly overhead at Jalpan?
I found my answer in the online "Table for the Declination of the Sun," located at http://www.wsanford.com/~wsanford/exo/sundials/DEC_Sun.html.
That table shows that today -- Saturday, May 26th -- at midday, the Sun will be directly overhead at latitude North 21°01'.
Since Jalpan's latitude is North 21°23', we're still a tiny bit north of today's declination.
The chart also shows that here in Jalpan, at North 21°23', the Sun will be most directly overhead at midday next Monday, May 28th. It won't be exactly, exactly overhead, for the ecliptic at midday will actually be one minute south of us, at North 21°22', but it'll be closest to our latitude on that date.
After next Monday on each consecutive day the ecliptic will continue drifting a little farther northward until the Summer Solstice on June 21st, when it'll stand exactly overhead at North 23°26' about 160 miles (260 kms) north of here, at the Tropic of Cancer.
After the Summer Solstice the ecliptic will begin migrating back southward on its journey to being overhead at the Tropic of Capricorn at South 23°26', on the Winter Solstice, December 22nd. The chart shows that on that return trip back south it'll again appear most exactly overhead at Jalpan on July 16th and 17th.
BIODIVERSITY IMPORTANT FOR HEALTH AND SANITY
My old birding friend Jarvis in North Carolina sent me a link to the online science journal World Science, sponsored by the UK's Royal Society. You can review the journal's current titles on my Online News Feed page at http://www.backyardnature.net/rss_wrld.php.
Among several very interesting titles listed there is "Biodiversity Good for Mental Health," accessible at http://www.world-science.net/othernews/070515_park-biodiversity.htm.
That article mentions a 1984 study documenting that patients in hospital rooms overlooking trees recovered faster than those in rooms with windows opening onto brick walls. A little Googling led me to other such studies:
References for the above and other studies are found near the bottom of the page at http://www.rmi.org/sitepages/pid1079.php.
In this world where diet supplements and other "health aids" occupy an enormous amount of shelf space at retail stores, why isn't it common knowledge that we heal faster in hospital rooms with views of trees instead of brick walls? In fact, why don't more people resist power companies cutting trees instead of burying cables underground as they do in Europe? And why isn't it criminal for land developers to clear forests from land even before they try marketing it? By now isn't it clear that attacking forests is attacking humankind?
It's clear that human behavior lags far behind evolving human understanding.
Someday, if humanity survives long enough to mature and grow wiser, the true value of windows with views of trees will be recognized not only at hospitals but at average people's homes. Architects will vie with one another to design structures inviting abundant natural light and fresh air, and average developers will sell lots with standing trees. Schools built amidst woodlots will be understood as providing environments most conducive to learning.
Someday, maybe, if humanity emerges from this era's wholesale destruction and general public ignorance of the Earthly biosphere, society will be reconstituted in ways harmonious with tree form and texture, people will live wind-through-trees kinds of lives, think sunlight-flecks-beneath-trees thoughts, and people will be so sensitized to, and informed about, the ecosystems around them that these remarks will be utterly comprehensible.
Best wishes to all Newsletter subscribers,