June 12, 2011
A WELL ORIENTED GOBY
The tide was going out leaving shallow pools that only the biggest waves managed to slosh into. Inside one basketball-size pool a pale gray, flat-headed fish half a finger long looked up at me, as shown at http://www.backyardnature.net/n/11/110612gb.jpg.
With the tide going out, soon not even the largest waves would reach the pools, so I wondered whether the fish might get stranded. In such an exposed, small pool he'd be easy pickings for a fish-eating bird. However, I was too busy taking the above picture to think much about it. Unfortunately, in that picture a blade of Turtlegrass awkwardly slants across the field, so after snapping the photo I slowly dipped my finger into the water to nudge the blade out of the way.
But, before my finger got close, in a flash, the fish took advantage of the remains of a big wave briefly washing into the pool. Half swimming, half squirming, he shot out of the pool onto the lowest part of the surrounding rock face and in less than 1/5th of an inch of water flopped and wiggled across a yard of limestone before diving beneath some Turtlegrass in the surrounding shallows.
Clearly, he'd known exactly the best escape route -- where the rock rim surrounding his pool was lowest and where open water was on the other side -- despite being unable to see it from inside the pool. And he'd coordinated his escape perfectly with the arrival of the remains of a large wave.
However, there was more: As I was turning away from the pool a certain flipping and wiggling caught my eye, and when I looked back into the pool, there he was again, having bodysurfed another wave back into it. How could such a tiny brain be capable of such timing, positional orientation and audacity?
The fish was a Frillfin Goby, BATHYGOBIUS SOPORATOR, distributed from South Carolina south to Brazil, along tropical Africa's western coast, and in tropical southeast Asia and Oceania.
I'm not the first to be in awe of the tide-pool-escaping-and-entering behavior of the Frillfin Goby. A 1951 article in American Museum Novitates #1486, published by the American Museum of Natural History, notes that "these fish are so well oriented before jumping that they always land safely in a neighboring pool or in the open water. The conditions are such that the fish could not possibly see the neighboring pools before leaping."
You can download that entire study in PDF format at http://digitallibrary.amnh.org/dspace/handle/2246/3993.
Now that I know what to look for, whenever I approach several small, close-together tide pools I watch to see if someone leaps from one pool to another, and often I do see it! This is a spectacle I've been missing until now, something that even Marcia didn't know about.
Frillfin Gobies are practically omnivorous, with a special affinity for crustaceans.
At the southern rocky point I was trying to photograph a black, very ornamented crab in a tide pool when suddenly a loud, piercing PIK! erupted from nearby. The visitor stood about fifteen feet away, as shown at http://www.backyardnature.net/n/11/110612pl.jpg.
With those long legs and a short beak slightly bulging at the end, he was clearly one of the six or seven plover species found here. But I thought that plovers were migrants and should have been gone by now. Also, the plover most frequently seen here is the Semipalmated, our nice picture of which appears at http://www.backyardnature.net/yucatan/semipalm.htm.
But notice that those Semipalmateds beaks are much shorter and smaller than our PIK!er's. This was a different species.
PIK!er was a Wilson's Plover, CHARADRIUS WILSONIA, a denizen of sandy beaches and mudflats approximately from coastal New Jersey south to Brazil and Peru.
So, shouldn't this bird have migrated northward by now? It turns out that Wilson's Plovers are permanent residents here. Northern populations are migratory, and part of Mexico's are, too. Along the southern Pacific and the southern Gulf of Mexico, except for northern Yucatán, Wilson's Plovers are only winter visitors. Also they're only winter visitors along the coasts of Belize, Honduras and Guatemala.
Who knows what quirk of evolutionary history accounts for such a curious nesting and overwintering pattern for the Wilson's Plover?
Possibly the most common bird along the road up our little sand ridge between the sea and the mangrove swamp is the Tropical Mockingbird, which is similar to Northern Mockingbirds and sings almost identically. Possibly our Tropicals are a little more aggressive than the Northern species. At least they are prolific mobbers. By mob I mean that in small groups they harass other birds, especially predator species. You can see a couple dealing with a Laughing Falcon at http://www.backyardnature.net/n/11/110612lf.jpg.
You'd be surprised how much thinking has been done about how and why the mobbing impulse arose during the course of evolution. Among the explanations are: To advertise the mobber's physical fitness and hence uncatchability; to distract predators from finding their offspring; to warn their offspring; to lure the predator away; to teach the offspring to recognize the predator species; to possibly injure the predator, and; to attract a predator of the predator itself. Wikipedia's excellent page on the matter is found at http://en.wikipedia.org/wiki/Mobbing_(animal_behavior).
When the above Laughing Falcon finally was driven away I got an interesting shot showing how, just before its wing's downbeats, it brings its wings -- which are shorter and more rounded than those of most falcons -- high over its back. Apparently this enables a more powerful purchase on the air. The picture can be seen at http://www.backyardnature.net/n/11/110612lg.jpg.
EYE IN THE SKY, SKY IN THE EYE
Especially if you know a little about Mexican birds, see if you can identify what KIND of bird is shown at http://www.backyardnature.net/n/11/110612tg.jpg.
I'd approached a shadowy clump of trees from which two birds were loudly calling chuk, chuk, chuk-chuk-cho-cho-cho-cho-cho-cho!... For several minutes they stayed hidden. Then, just as I was giving up and leaving, the one in the picture flew out and perched on a snag in the mangroves. Seeing the bird's stocky body, long, square-tipped tail and short beak, it was clearly a trogon. But what trogon is all black, and what trogon is graced with such a spectacularly blue eyering?
It's the Black-headed Trogon, sometimes lumped with the Citreoline Trogon. It's TROGON MELANOCEPHALUS.
Actually, we saw a Black-headed Trogon up at Hacienda Chichen this February. It's shown from the front at http://www.backyardnature.net/yucatan/trogon.htm.
In that picture you can see that that bird's eye ring is a much paler blue. I'm guessing that during breeding season the blueness intensifies. Also I'm guessing that our current bird is a female, for the backs and tail-tops of male Black-headeds are greenish, and their rumps are bluish, while our bird seen from behind looks all black. That, or somehow the lighting obscures the bluishness and greenness. That could be, because I read that the female's eye ring is duller than the male's, and I can hardly imagine a bluer eye ring than this one's.
When our black-backed bird dove toward something below it, for a split second the bird's bright yellow bottom flashed against the mangroves' deep greenness, and that was pretty.
Several times I've mentioned our biting flies. They're small, about 3/8ths of an inch long (1cm), yellowish, and if you settle anyplace for long -- except on the beach where wind keeps them down -- they head straight for you, especially your lower legs. They hurt, too, sometimes leaving blood trickling down your legs. If they bite a finger or toe, for awhile the appendage may swell, stiffen and itch. You can see one at work on the tender skin right below one of my fingernails at http://www.backyardnature.net/n/11/110612yf.jpg.
Up North we call small, biting flies with black markings on their wings deerflies (genus Chrysops), while much larger flies with clear wings are horseflies (genus Tabanus). Our little biting fly belongs to the Horsefly/Deerfly Family, the Tabanidae, but is placed into a completely different genus, Diachlorus, of which about 23 species occur in the American tropics. Of these 23, one species is especially abundant and widespread, so I'm figuring that that's ours -- DIACHLORUS FERRUGATUS. In English often it's known as the Yellow Fly, though Belize's Creole speakers call it Doctor Fly. The species is found from New Jersey to Texas south through Mexico to Costa Rica.
As with mosquitoes, it's the female who bites. Both sexes eat flower pollen and nectar for energy, but the female needs blood for her eggs to develop. Biting is especially bad near water and trees. I've found insect repellent to be of a little use, but not for long. In areas with lots of them, experts suggest gloves and headnets.
I have a favorite place up the beach where each morning I like to sit in the sand, lean against a tree trunk left by the last storm, dig my heels into the sand, and watch the early morning sun work its way up through clouds out over the water. The other day the tide was as high as it gets, so breaking waves wetted the sand and tossed-up Shoalgrass at my feet. It wasn't long before I realized that all over my feet and legs something very small was gnawing on me.
The skin on my feet and legs was heavily dusted with what looked like multitudes of cream-colored lice -- tiny creatures with softish-looking bodies with white legs, and black, pinprick eyes.
I started to nudge one with a finger but before my finger reached him he disappeared. Others did the same thing. They were JUMPING so quickly that my eyes and brain couldn't register their movement. In fact, now that I looked, when I waved my foot over the sand, thousands of these pale little beings sprang up like cooking popcorn.
I'd met critters like these before, so I knew that I'd dug my heels into sand and Shoalgrass working with springtails. You can see a springtail gnawing on my skin, and another one, about 1/6th of an inch long (4mm), grazing in wet Shoalgrass, at http://www.backyardnature.net/n/11/110612sp.jpg.
The general body plan of a springtail is something like that of an open safety pin, with the lower pin part replaced with a tail-like appendage shaped like a fork, known as the "fercula." The springtail springs by snapping downward its furcula.
Springtails are not exotic animals. One expert describes them as the most abundant of all soil- dwelling arthropods. As well as being numerically superabundant, they're very diverse, with over 8000 species recognized worldwide.
For most of my life I've thought of springtails as forming one of the largest orders of insects. Nowadays with genetic sequencing most experts no longer regard them as insects. They're a distinct kind of life form arisen early during evolutionary history, and so far there's little agreement on where they belong on the Phylogenetic Tree of Life. Some experts regard them as constituting their own class. To put that in perspective, mammals form one class, and birds another.
What makes springtails so uninsectlike? For one thing they're wingless, but more profound is their "internal mouthparts." With Google I've tried to figure out how internal mouthparts work but can't. I do know that when springtails with their internal mouthparts gnaw on my skin it feels just as if they had external ones.
A WILD YELLOW-OLEANDER
We've looked at the Yellow Oleander, Thevetia peruviana, often planted along streets and around people's houses in much of tropical America. It's at http://www.backyardnature.net/yucatan/y-oleand.htm.
Along our sandy roadsides there's a very common, dense and much-branched bush getting 12 feet or so high (3.6m). It's a native, different species of yellow-oleander, THEVETIA GAUMERI. You can see it at http://www.backyardnature.net/n/11/110612yb.jpg.
Its yellow, funnel-shaped flowers are very similar to the much-planted Yellow Oleander, as shown at http://www.backyardnature.net/n/11/110612yc.jpg.
Our sandy-road yellow-oleanders have fruits similar to those of the planted species, and when mature turn red as well. Nowadays they're still green, though, as seen at http://www.backyardnature.net/n/11/110612ye.jpg.
So, the neat thing about our wild yellow-oleander is that it's so similar to the famous, much-planted Yellow Oleander, but it's just a different species, one hardly anyone knows about. Our species specializes in coastal scrub from the Yucatan south to Costa Rica.
Both yellow-oleander species are member of the Dogbane Family, the Apocynaceae, and as is typical of that family they ooze milky, sticky latex when injured. Of course the Maya have noticed this and use the latex medicinally in many ways -- for everything from boils to snakebite, for holding cut skin together, for mange and inflamed skin, to keep down infection, on and on.
Already we have a nice page on Sea-grapes, available at http://www.backyardnature.net/yucatan/seagrape.htm.
When pictures for that page were taken, there were no fruits available -- no grapes. Now at least some of our Sea-grape shrubs are heavy with grapes, as seen at http://www.backyardnature.net/n/11/110612cc.jpg.
Those mothball-size "grapes" are still a little immature, even though you can see that many already have disappeared from their slender, drooping rachises. My Maya friend Martín explained what's going on:
"It's the chachalacas," he said. "They come every morning to eat the grapes, even before they're mature and juicy When they're ripe, they're yellowish to rosy."
I'd like to find some ripe sea-grapes because I read that they taste good, are tart to sweet, and can be eaten raw or made into jelly or wine. However, I've looked for some all week and so far the chachalacas are winning.
Most of the insides of the grapelike fruits are occupied by a single hard seed and inside that seed you can see something special: The embryos inside most seeds are curled, but Sea-grape embryos are straight. You can see one looking like an egg on a golf tee at http://www.backyardnature.net/n/11/110612cd.jpg.
Evolutionary taxonomists usually regard straight embryos as a more primitive trait than curved ones.
Occasionally along the beach you see what's shown at http://www.backyardnature.net/n/11/110612st.jpg.
That's where a sea turtle has come ashore to lay eggs, leaving her flipper marks in the sand. They come in at night, and artificial light confuses them. Lots of predators, including people, eat their eggs and the turtles themselves. There aren't nearly as many sea turtles as there used to be.
Stories drift around about Pancho, who lives in a shack up the beach. What's relevant here is that nowadays he's eating sea-turtle eggs and the turtles themselves. He curries favor with his Mexican neighbors by sharing his eggs and turtle meat with them. A neighbor tells me that he gave 50 turtle eggs to a family who didn't really want them, so, after Pancho left, the family threw the eggs away. "Pancho gets to all the nests," I heard, "and he digs out every egg, all up and down the beach."
One way to think about Pancho is that, in terms of the sea-turtle situation, he's The Trickster. Most cultures sophisticated enough to know that everything has an Achilles Heel, recognizes The Trickster in its mythology. The Trickster is the one who always screws things up by unexpectedly playing tricks or otherwise not respecting normal rules and conventional behavior.
The Maya with their gnomelike alux recognize The Trickster. Native North American cultures often taught their children about the Coyote or Raven Trickster, and Black slaves in the US with long memories of Tricksters back in Africa told stories about Br'er Rabbit.
You can understand The Trickster's value in everyday living. Keeping The Trickster in mind, you never over-invest in any one thing, for you assume that at the very moment you're most dependent on that single thing The Trickster will come along and mess it all up. People properly respectful of The Trickster don't build nuclear power plants producing spent fuel that will remain lethal for thousands of years.
So, sea turtles co-evolved with their environment for millions of years, until everything was working just right, the ocean poetizing in terms of peacefully grazing big green sea turtles, and then along came Trickster Pancho, and thousands and thousands of Panchos, which the elegant evolutionary impulse bringing forth sea turtles seems never to have provided for.
But, of course, Nature did think of The Trickster, for The Trickster is part of Nature -- sometimes manifesting as an earthquake or hurricane, or war or pestilence, a comet striking the planet, or just general bad luck. Whatever, The Trickster always comes.
Moreover, there are tricks beyond the everyday sort. For, even after all sea turtles and Tricksters are gone, the creative impulse will remain. New life and new poetry will arise, if not on Earth, then someplace else.
And then the trick will have been on all of us.
Best wishes to all Newsletter readers,
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