July 31, 2011
COATI IN A SNAG
Up at Hacienda Chichen, coatis, NASUA NARICA, were fairly common, but they moved too fast in too shadowy places for me to ever get a good picture. This Tuesday morning, then, I was happy to see one quietly perched in the fork of a dead snag in the mangroves, as shown at http://www.backyardnature.net/n/11/110731ct.jpg.
They say that coatis are common here, sometimes showing up daily raiding the compost heap, but this is the first one I've seen since arriving. Apparently they change their routines from time to time. In June I mentioned that I'd been seeing rabbitlike agoutis nearly every day, but since that report most weeks have passed without a single one appearing. Lots of animals periodically change their routines.
If the coatis I've seen until now have been hurrying about in dark places, why was this one perched unmoving in a sunny snag? Judging from that nasty wound in his snout -- and anyone can see that he's a male -- he might have up there trying to stay out of trouble after being hurt in a fight. My guess, though, is that he was trying to stay above the mosquitoes.
For, last Tuesday morning the wind was the calmest I've seen it since I've been here. Consequently that day mosquitoes drifting from the mangroves were even more pestilential than the biting flies, and that's saying a lot. When the wind blows normally, mosquitoes just can't get to us, and even the flies avoid the extra-windy beach. Also, mosquitoes stay close to the ground. I'll bet that that coati just was waiting until the sun got a little higher and the mosquitoes cleared out more before returning to the ground.
MARTINS ON THE MOVE
I'd gone looking for the recently fledged Common Black Hawk we've been watching but he wasn't to be found. However, not far from the old nest, thirty or so twittering, antsy swallows, I thought, were perched on a snag. You can see what they looked like at http://www.backyardnature.net/n/11/110731pm.jpg.
If we'd been up at Hacienda Chichen I'd have called them Ridgway's Rough-winged Swallows and not given a second look. However, so far this summer I've not seen a single swallow here, so I wondered whether they might be something special. Also, these birds somehow -- even with all their twittering and fidgeting -- didn't seem quite as hyperactive and nervous as the Hacienda's Ridgway's. Once I got the picture onto my laptop screen I saw why: They weren't Ridgway's. They weren't even swallows.
First of all, even with their dusky chests and throats, they're not Ridgway's Rough-wingeds because their tails are too deeply notched. Then I thought of Gray-breasted Martins, which are fairly common throughout lowland Mexico, but then I began noticing that some of the birds appeared to be completely black with a bluish cast, not just silhouetted so as to look black. In the picture, the bird at the branch's tip looks completely black while the one next to it, in the same light, has a pale breast. These are Purple Martins!
But, these days, aren't Purple Martins supposed to be summering up north? Since they nest far to the north of here, and winter in South America, they appear in the Yucatán only during spring and fall migration.
In A Guide to the Birds of Mexico and Northern Central America, Howell's fine-print on Purple Martin distribution says that the species is common to fairly common on Mexico's Atlantic Slope (here) during the spring migration from late January to May, and during the fall migration from July to October...
So, that's it! Here on the Yucatán's Caribbean coast already in July (July 24th, to be exact) these Purple Martins -- mostly immatures in the picture -- are inaugurating the fall migration season. The birds in the picture are freshly arrived from North America and are headed south to South America, mainly Brazil.
Yesterday, Saturday morning, for about half an hour a diffuse cloud of Purple Martins flew along the beach low enough for the naked eye to easily make out their forked tails, and every one of them was headed south. At any one time five or ten birds might be view, so maybe in all a couple hundred passed. After that half hour passage, for another half hour a few lone stragglers followed.
So, how about that? In a flash, in this land of eternal summer, my personal general perception of the current season has flipped from its being "late spring" to "early fall," without having ever noticed a "summer" at all.
BLACK HAWK FLEDGLING UPDATE
The Common Black Hawk nestling we last saw around July 10th finally turned up again this Wednesday, July 27th. Between those dates I never saw him at all, though often out in the mangroves one of the adults would be perched not seeming to be doing much besides watching, so I've guessed that the adult was watching the fledgling down in the mangrove tangle too low for me to see.
On Wednesday the fledgling swooped across the road right in front of me while the adult perched high in a dead tree in clear view not far away. The fledgling landed near the old nest tree and seemed curious about me. The adult kept calling with what sounded like a fat man's hardy-har laugh expressed completely in squeaky whistles. The fledgling also whistled, but only in short phrases, with what anthropomorphically seemed to me a questioning tone addressed to the adult. Speaking of anthropomorphism, to me the picture of the kid looks as if he's smiling good-naturedly as he calls back to his mom. You can see what you think at http://www.backyardnature.net/n/11/110731bk.jpg.
You might enjoy reviewing all our Black Hawk nestling pictures on our ever-growing Common Black Hawk Page at http://www.backyardnature.net/mexnat/blakhawk.htm.
GRUNT IN THE GRASS
Some visitors and I on a beach walk came upon three young Mexican men fishing. They'd waded out about fifty feet to where the water was waist deep and were tossing their lines into spots where they thought there'd be fish. They used hooks, lines and sinkers, but no poles or rods and reels. With their right hands they'd toss lines wrapped around their left hands.
As we approached, one man was coming ashore with a fighting fish on his line. You can see his catch lying in wave-deposited Turtlegrass at http://www.backyardnature.net/n/11/110731fi.jpg.
Back at Marcia's little visitor library, in Humann and DeLoach's Reef Fish Identification: Florida, Caribbean, Bahamas, it was easy to get the name of such a boldly patterned, brightly colored fish. It was the Bluestriped Grunt, HAEMULON SCIURUS. Several species are more or less this color and also bear slender, longitudinal stripes, but this one also has dark tail and rear dorsal fins.
The species is described as common in waters around Florida, the Bahamas, and throughout the Caribbean, and uncommon as far north as South Carolina. The book says that Bluestriped Grunts congregate in small to midsized schools near protective reefs, especially drop-offs, though ours was caught well away from the reef, among big beds of Turtlegrass. Elsewhere I read that grunts in general are especially common around reefs next to large expanses of grass beds and sand flats, which is exactly what we have here.
Why are grunts called grunts? It's because of the sound they produce when their teeth grind deep within their throats, amplified by their air bladder.
I always regret seeing fishermen lay their catches on dry land where the fish slowly die, as was the case with this fish. When I was a kid I was told that fish can't feel anything, but eventually I used my own brain to see that they are as sensitive to touch and pain as any other complex living organism, maybe more so than most. I don't like presenting the picture of a slowly dying fish, but maybe there's value in the picture reminding us what lovely creatures are out there, all the time, living their own beautiful lives.
I was gathering wool gazing into a tidal pool at low tide when something I'd been thinking was a mere alga- and-debris-covered irregularity at the bottom of the pool began purposefully trudging across the pool's bottom. I took a picture of the thing but because of its effective camouflage you can hardly make it out in the resulting picture. You can see if you can find it at http://www.backyardnature.net/n/11/110731cc.jpg.
In that picture the object in question occupies about 1/20th of the image and appears a little right of center. I grabbed the thing so you can see it better at http://www.backyardnature.net/n/11/110731ce.jpg.
Flipping it over I saw what's shown at http://www.backyardnature.net/n/11/110731cd.jpg.
In that picture the two flattened, dark-purple-dotted items toward the body's rear are the last of four pairs of flattened, paddle-like legs modified to help with swimming. Legs adapted like this are referred to as swimmerets. The body is about an inch long (2.5cm).
This time Marcia's Guide to Reef Creatures didn't help much with identification because the closest picture found in it didn't bear a name. The authors explained that crabs in this group often simply can't be identified without collection and "scientific examination."
As a group these crabs are informally known as Decorator Crabs. They seem to occur widely, and are distributed through several genera. They camouflage themselves by attaching a wide range of marine life and debris to tiny hooks on their carapaces, snouts and legs. The attached organisms often remain alive, and occasionally even reproduce. Other crabs of the same species in the same pool were greenish because their bodies were adorned with green algae.
If anyone can figure out what genus or species this is, let me know. Bea, our usual volunteer identifier in Ontario, is on vacation!
BARNACLES & LIMPETS
Last week's section about a barnacle shell found on the beach began with, "Though I'm just a beginner in seashell identification..." Then I proceeded to make an error that only a rank, rash amateur would make. Everything written about barnacles in that piece was correct, but the shell itself was a limpet shell, as Eric in New York, Sue in Cyberspace, Seth in Maine and Cotting in the Yucatán soon let me know.
"I first became aware of them in Africa where they were so big you could cook and eat them. Great stew!" Cotting wrote. Cotting even suggested a name for our shell: the Barbados Keyhole Limpet, FISSURELLA BARBADENSIS. To see the shell prettily in situ go to http://www.backyardnature.net/n/11/110724bn.jpg.
Front and back views are at http://www.backyardnature.net/n/11/110724bo.jpg.
Limpets, now I know, are not a breed of short-legged dog, which I'd thought earlier, but rather saltwater and freshwater snails with simple shells conical in shape, and either not coiled, or appearing not coiled in the adult stage. Most limpet shells bear no crater- like hole at the shell's top, but the "keyhole limpets" do. You might enjoy an extensive page showing many keyhole limpets from across the world, including Cotting's Barbados Keyhole, here.
Keyhole limpets occur throughout the world's oceans, in most marine environments, and most species feed on their fellow sea creatures, such as bryozoans, sponges and tunicates. On the Internet a keyhole limpet expert says that the keyhole is the exit port for waste products. Limpet species with closed shell tops have an opening below the shell.
Sara in Washington State also was paying attention to the last Newsletter, but she was wondering about the honeybee trying to pry into the Coconut Palm flower at http://www.backyardnature.net/n/11/110724pn.jpg.
Once I thought about it, Sara was right to wonder about a honeybee here, because this wouldn't seem like an appropriate place for them. First, honeybees are invasive species introduced from Europe and in our immediate area no one is keeping hives of them. If wild colonies have become established in trees here along the coast, surely 2007's Hurricane Dean would have destroyed them, as it did so many other forms of wildlife.
It turns out that one of our managers here, my Maya friend Martín, runs a beekeeping business on the side, so I asked him about honeybees showing up here on the beach 20 kms north of Mahahual.
"It' a little surprising to see European honeybees here," he said. "However, a man in Mahahual used to keep them and some must have become established up here. The man's colonies gradually disappeared, some getting sick and dying, in others the bees just flying away. The big problem here is that there's just the mangroves and this narrow sand rise along the beach, and there aren't many kinds of plants in these places. There are times of the year when there's just nothing producing much pollen or nectar."
Martín also told me that around here practically all honeybees are "Africanized" -- what several years ago movie producers called "killer bees." But beekeepers are content with their new easy-to-antagonize bees because "Africanized" bees produce far more honey than traditional European honeybee types.
AGERATUM IN THE SAND
Northern wildflower fanciers will find an herbaceous composite flowering along the sand road these days vaguely familiar. Its leaves and pale blue heads are at http://www.backyardnature.net/n/11/110731ag.jpg.
A close-up of some heads, the one on the left broken open so you can see how its slender flowers are packed so densely together, and how the usual white, fuzzy "pappi" atop the future achene-fruits have been replaced with low, crownlike structures, is shown at http://www.backyardnature.net/n/11/110731ah.jpg.
Some will say the herb looks like one of the blue eupatorium wildflowers, such as the Blue Mistflower, and it's true that it's distantly related. Gardeners might peg it as an ageratum. In fact, it is an ageratum, AGERATUM MARITIMUM, one specializing in sandy, saline soils like ours. The species is found mostly along the coasts from the southernmost tip of Florida through the Caribbean, south at least to Honduras.
The only English name found for the species is Cape Sable Whiteweed, which is a bit unfortunate because the plant isn't a weed but rather a highly adapted wildflower, it's not white, and Cape Sable is the name of the southernmost tip of Florida where the plant can be found, and has nothing to do with the species' main area of distribution, which is along Caribbean coasts. A good name would be Coastal or Caribbean Ageratum.
At http://www.backyardnature.net/n/11/110731ai.jpg you can see the plant's leaves, which are a little unusual for and ageratum because they're semi-succulent. We've seen that leaf and stem succulence is an adaptation for many species living in salty soil. Succulent leaves retain water between rains.
A SOFT, GREEN SPURGE
On this low, windswept, sun-drenched sand rise paralleling the beach between the Caribbean and big coastal mangrove swamps, one grows accustomed to plants showing adaptations to the harsh environment -- toughness, succulence, silvery-wooly hairiness, etc. However, out behind the employee's dorm where rainwater runs off a tin roof, out of the wind and shaded for part of the day, a small community of normal weeds has taken root. Sometimes I stand looking at their trusting softness and innocent, simple greenness just for a break from the environmental harshness elsewhere.
One if those moisture-loving, shade-thriving species is EUPHORBIA HYSSOPIFOLIA, a weedy native of the tropical and warm-tending Americas, and invasive in most of the rest of the world where there's enough moisture and heat for it. In the US it's found in the southernmost tier of states. You can see a sprig of our plant with inch-long leaves and tiny white flowers at http://www.backyardnature.net/n/11/110731eu.jpg.
A close-up of flowers showing the amazing Euphorbia feature of the oval ovary on a bent stem dangling outside the main flower body is shown at http://www.backyardnature.net/n/11/110731ev.jpg.
In that picture, the almost heart-shaped item in the center is an ovary, or future fruit. It dangles from the flower just below it. Each flower seems to bear four white petals, but in fact the white things are petal-like appendages of nectar secreting glands.
Found in so many English-speaking lands, Euphorbia hyssopifolia goes by lots of English names. The USDA seems to have settled on the name Hyssopleaf Sandmat, but others sometimes call it Leafy Spurge. Traditionally many members of the huge genus Euphorbia (over 2000 species as currently delimited) are known as spurges.
That word "spurge" has good roots, deriving from the Middle English/Old French "espurge," meaning "to purge." That name refers to the fact that the plants produce a white sap often regarded as purgative -- if taken internally, you vomit. In fact the milky juice exuding from spurge leaves is rich in alkaloids that can be toxic or medicinal, depending on dosage. Some Maya use the sap for "tired eyes," putting the juice into the eyes. You can see a torn leaf exuding milk at http://www.backyardnature.net/n/11/110731ew.jpg.
Every day, usually soon after sunrise, I spend some time watching the waves come in. You pick one out maybe 50 feet away, watch it swell as it approaches, then right before hitting the beach it sucks up white sand and sort of trips over itself, its white, foamy crest dramatically collapsing before it. You can see what such a typical wave looks like at http://www.backyardnature.net/n/11/110731wv.jpg.
Watching waves come ashore is a soothing, esthetically pleasing experience that roots me in placidness for the rest of the day. Also, I think it's one of those many occasions when Nature "teaches" us how reality is structured -- "imparts her paradigms," as sometimes it's expressed.
What does watching waves teach? Maybe the most powerful insight comes from seeing how the ocean, with all its irregularly shaped and sized waves arriving at irregular intervals, in the end reveals itself as a smoothly functioning, law-abiding system. We can even be mathematical about our approaching waves: A wave's speed is the distance between wave crests (wavelength) divided by the time between two passing crests (period). In Nature, there are hidden patterns and cycles that reveal a lot about reality that's not immediately obvious.
Watching waves even helps us order our minds about ourselves. For example, maybe you've done this: You choose a wave a bit out there and say, "I'm that wave; what happens to that wave will predict how my own life will turn out... "
And then maybe the wave joins with another becoming a big wave and seems about to make an enormous splash on the beach, but when it gets there there's such backwash from the previous wave that your wave collapses ignobly into a bunch of disorganized spume well before reaching the sand.
Or maybe the wave immediately begins shrinking, but right before reaching the sand somehow lurches, a rainbow sheen forms inside its curl, and it collapses with great fanfare, washing much farther up the sand than other waves.
No matter what happens to your wave, the wave becomes a catalyst for further rumination on how it's like your own life. In fact, if you let them, waves -- especially those who start off big but then collapse before reaching shore -- can stir up thoughts you'd just as soon not deal with. You can find yourself sitting on the beach consciously ignoring the waves, wanting a pelican to come along for distraction.
But, when I get into that shape, I know I just need to sit there a little longer. That's because always, if you watch enough waves, you get so mellow that whatever story the waves tell, it's OK. You realize that in the end they're just ephemeral ripples on the vast, timeless ocean. And that's the most profound teaching of all.
Best wishes to all Newsletter readers,