August 7, 2011
Up at the northern rocky point three Brown Pelicans paddled by in a row, bobbing on the waves, as seen at http://www.backyardnature.net/n/11/110807pl.jpg.
The interesting thing was that the lead pelican had a white head and neck, while the second one's head was white but the neck was mostly brown, and then the third pelican's head and neck were all brown. What did it all mean?
It turns out that juvenile Brown Pelicans are brown overall with whitish bellies, so the third bird in the row is a freshly minted youngster. Just to our north in Sian Ka'an Biosphere Reserve, Brown Pelicans nest in colonies so a good guess is that our birds are from there. (Magnificent Frigate Birds, Roseate Spoonbills and Jabiru Storks also nest in Sian Ka'an.)
Our middle bird displays plumage typical of an adult Brown Pelican during the summer -- white head, and a brown neck with white from the head extending down the front of the neck. But the front bird displays the typical plumage of an adult in winter -- an all-white head and neck.
So, two adult birds leading a youngster, and the two adults can't agree on whether it's time to dress for summer or winter...
In the southeastern US I'm accustomed to seeing night-herons in wooded freshwater swamps, so when a chunky, medium-size heron showed up in mid-day sun at the water's edge on the sandy beach, I wasn't thinking "night-heron." The thick-necked silhouette suggested a Bare-throated Tiger-heron, fairly common here in the mangroves, but up closer it bore different markings. Happily, the bird allowed me to get within twenty feet, so you can see what he turned out to be at http://www.backyardnature.net/n/11/110807hr.jpg.
He is indeed a Yellow-crowned Night-heron, NYCTICORAX VIOLACEUS. In A Guide to The Birds of Mexico and Northern Central America, Howell says that in this part of the world they occur in mangroves and coastal areas, including freshwater marshes and open beaches, so the species is more adaptable than I'd thought.
Is this bird migrating? In the Yucatan, Yellow-crowned Night-herons are nesting permanent residents. The one in the picture may well be wandering a bit, maybe a young one out exploring prior to settling down. In fact, Howell says that adult Yellow-crowned Night-herons have amber or scarlet eyes, while juvenile eyes are orange-yellow to amber. This one's eyes look more orange-yellow than amber, so that's a vote for it being a juvenile.
AN EGRET FLYING BY
Not far down the beach from the night-heron a large, white wading bird stalked prey in shallows about fifty feet into the water. He was more nervous than the night-heron so he flew up before providing a good look. However, as the snowy bird passed by he offered a pretty sight against the blue ocean, as shown at http://www.backyardnature.net/n/11/110807eg.jpg.
With that yellowish beak he's not a white immature Great Blue or Little Blue Heron. He lacks the Snowy Egret's yellow feet, and his neck is too slender and his bill too big to be a Cattle Egret, so he's the Great Egret, in old books called the Common Egret, ARDEA ALBA.
Great Egrets also are nesting permanent residents in coastal Yucatán, so neither is this bird currently engaged in long-distance migration -- despite this being the first of this species seen since I got here three months ago.
In fact, the recent appearance of hoards of Purple Martins, the night-heron and this Great Egret all signal a whole new chapter to this year's birding here on the southeastern Yucatán coast. Though even still there aren't many birds out there, species diversity along our part of the beach has practically doubled within the last couple of weeks.
PURPLE MARTINS GALORE
Last week we were impressed by twenty Purple Martins resting on a snag as they migrated from North America back to South America for the winter. Now look at http://www.backyardnature.net/n/11/110807pr.jpg.
That's Mayan Beach Garden's antenna tower at midday last Tuesday. For the rest of the week no such gathering took place, though the next day at the same hour five lonely birds perched at the very top. In the picture, of the ones on the diagonal wire, only about one in fifteen were black-breasted adult males.
CATERPILLAR CROSSING THE ROAD
At http://www.backyardnature.net/n/11/110807ct.jpg you see the pretty, orange, silver-striped, black-spined caterpillar found crossing the white-sand road paralleling the beach. The sharp-looking, branched spines look like those of some stinging caterpillars but they're perfectly harmless, all bluff.
Since Bea our volunteer bug identifier is on vacation I almost didn't bother photographing our road caterpillar, knowing I'd not take the time to plow through the jillions of images answering to Google's image-query string "caterpillar orange black spines." However, then I remembered that around here we have only a relative handful of butterfly species, so why not just see if our road caterpillar is one of those?
As it turned out, the caterpillar belongs to our most common butterfly species, the Gulf Fritillary, whose orange and black markings are seen at http://www.backyardnature.net/yucatan/mariposa/butt086.jpg.
An even more eye-catching side view is shown at http://www.backyardnature.net/yucatan/mariposa/butt088.jpg.
The Gulf Fritillary caterpillar eats passion-flower vine, genus Passiflora, which grows very commonly among roadside trees here.
Most Gulf Fritillary caterpillars illustrated on the Internet lack the silvery lines so conspicuously extending the length of ours. In fact, caterpillars of this species can vary tremendously. There's a whole page just on this caterpillar's variations at http://www.butterflyfunfacts.com/unusualgulflarvae.php.
You might also enjoy a page nicely illustrating the Gulf Fritillary's development from egg to adult at http://www.floridanaturepictures.com/butterflies/butter25.html.
GOOSE BARNACLES ON A WASHED-UP TREE
Already during my 2008 visit here we learned what Goose Barnacles look like lying in the sand, as seen at http://www.backyardnature.net/yucatan/goose-ba.jpg.
Goose Barnacles -- which are crustacean arthropods -- are very commonly seen on the beach here, attached to things that have been floating long distances. For instance, the other day a medium-sized tree trunk washed up on the beach covered with them, as shown at http://www.backyardnature.net/n/11/110807gb.jpg.
A close-up showing them clustering on we wood is shown at http://www.backyardnature.net/n/11/110807gc.jpg.
In that picture notice the dark brown, fleshy "stalks," or peduncles, extending from each shell and attaching to the wood. These peduncles are characteristic of the "stalked barnacles." In contrast, the shells of "acorn barnacles" attach directly the substrate and lack peduncles.
While Googling info about the peduncles I came upon this little fact: In terms of relative body size, barnacles possess the largest penises of the entire animal kingdom. They extend as much as eight times the barnacle's length. This makes sense if you're a male interested in procreation but you're stuck to one spot.
Several stalked barnacle species are called goose barnacles, but so far the only one I've seen here, the one in the pictures, is LEPAS ANSERIFERA. Another similar goose barnacle species is said to occur here, Lepas anatifera. In the pictures you can see how Lepas anserifera's shells are deeply, broadly and shallowly grooved. Lepas anatifera's shells are etched with much finer striations.
VITEX IN BLOOM
When I arrived three months ago already a certain small tree along the sand road bore a few flowers, but I've been waiting to photograph until the flowering reached more of a peak. Now that's happening, as shown at http://www.backyardnature.net/n/11/110807vx.jpg.
At the left in that picture notice the tree's "palmately compound" leaves -- leaflets arising from a single spot atop the petiole, like fingers from the palm of a hand. When you see such leaves associated with purple, bilaterally symmetrical flowers, you should think the genus Vitex is a big genus of about 250 mostly tropical and subtropical species. About 18 Vitex species have been brought into cultivation, mainly because they're such pretty plants.
Our species is VITEX GAUMERI, occurring from southern Mexico south to Costa Rica. Its main English name appears to be Fiddlewood, which is a name shared with several related and unrelated trees. Sometimes Vitex gaumeri is called Walking Lady; in Maya it's Yax-nik. Vitex is a genus in the Verbena Family, the Verbenaceae.
You can see Vitex gaumeri's flower, beautifully adapted for pollination -- the yellow "nectar guide" leading from the pollinator's "landing pad" beneath stamens whose anthers will daub pollen onto the pollinator's back as it enters the corolla's throat -- at http://www.backyardnature.net/n/11/110807vy.jpg.
The IUCN's "Red List" classifies Vitex gaumeri as "endangered," probably because of tremendous habitat destruction throughout the lowland area the plant lives in, and because of overharvesting of the tree for its exceptionally fine wood. The IUCN listing is at http://www.iucnredlist.org/apps/redlist/details/37086/0.
The road between Mahahual and Sian Ka'an Biosphere Reserve skirts several little ponds with grassy margins. Some of those "grasses" are spectacular, and some aren't even grasses. For example, you can see a small part of a single clump about ten feet high (3m) and as wide as about three large refrigerators at http://www.backyardnature.net/n/11/110807sc.jpg.
Besides its robust vigor, something catching my eye about this plant -- in the picture most easily seen in the bottom, left corner -- was how its leaning stems sprouted leafy plantlets for future vegetative reproduction. A close-up of a plantlet's knobby base is at http://www.backyardnature.net/n/11/110807sd.jpg.
The plants were a little past their flowering peak, but old inflorescences were still present, as seen at http://www.backyardnature.net/n/11/110807se.jpg.
Despite its outward appearance, this plant was not a grass -- not a member of the Grass Family, the Poaceae. Instead of its stems being round in cross-section, like those of grasses, they were triangular. Also, its flowers were not arranged in spikelets and florets the way grass flowers are. Our giant's tiny, messy-looking flowers are shown at http://www.backyardnature.net/n/11/110807sf.jpg.
This is a member of the Sedge Family, the Cyperaceae. That's a big family of about 5,500 species in 109 or so genera, centered mostly in tropical Asia and South America. To give you an idea of how the Sedge Family compares with the Grass Family, in my Flora of McLean County, Kentucky, done for my Master's thesis I listed 55 grass species, but only 33 members of the Sedge Family -- of which 22 were sedges, or members of the genus Carex.
The plant we're dealing with here, however, isn't a Carex or any genus found back in Kentucky. It's CLADIUM JAMAICENSE, known as Sawgrass, even though it's not a grass. Sawgrass is famous as being the dominant flowering plant in the Florida Everglades. When you see hovercraft skimming across the Everglades' "River of Grass, that "grass" is the Sedge-Family member Cladium jamaicense. You can see the tiny, sharp blade teeth behind the name "sawgrass" at http://www.backyardnature.net/n/11/110807sg.jpg.
If a Sawgrass blade cuts at your hot, sweaty arm just right, a rather neat little bleeding cut results.
Sawgrass is such a robust, fast-growing plant that researchers are looking into its potential for producing ethanol fuel.
Many birds nest and feed in Sawgrass clumps, and various reptiles and amphibians find food and shelter there. The plant's seeds are abundant and nutritious. In the Everglades, Alligators use higher ground within Sawgrass stands for nesting sites.
Sawgrass is native from the Southern US through the West Indies, Mexico, and Central America into tropical South America. In this local area Sawgrass only spottily occurs, mostly at the bases of elevated roads crossing wetlands.
It's worth noting that not only have we seen that the dominant palm in our mangrove swamps is the Paurotis, Acoelorrhaphe wrightii, which is the characteristic palm of Florida's Everglades, but also our Sawgrass is the Everglades' most abundant flowering plant.
The other night I pegged my tent on the beach not far from the northern rocky point, about ten feet in from the waves. As I put the tent together, stiff wind off the water kept ballooning it out, dragging me into a downwind Icaco bush. Pegs stuck in the loose sand hardly held at all. Weighing down the tent's corners with driftwood, eventually it got built.
The moment I pulled myself inside the tent I knew it'd been worth the effort. Here in the tropics it's hard to ever feel "snug," but sitting cross-legged gazing through the netting of the tent's entrance, a wave of peaceful snugness swept over me.
It was dusk and out over the Caribbean seven well defined thunderheads lined up on the horizon, all drifting shoreward, and most with lightning flashing below them. Waves broke right before me, white foam rushing up to the door. The tent's nylon sides flapped explosively in roaring wind. Cozily cocooned inside the tent, the world around me seemed to tingle with a sense of anxious expectation.
Once it got dark, the fast-cooling air flickering with electricity, I laid back on the tent floor. Sand beneath the floor was hot from a whole day's glaring sunshine. As dark, chill, wet air washed around and through the tent, my body seemed to float atop a solid, glowing bed of shimmering warmth.
Suspended between the air's chill, impersonal commotion and the Earth's own warm, nurturing radiations I reflected that the sand's heat was stored-up solar energy, yes, but also the seven approaching storms similarly were packets of solar energy poetically releasing their energy as rushing air, rain and lightning.
In fact, there inside the tent between two dancing vocabularies of energy transfer, it grew clear that I myself was a transient expression conjured by something aiming to facilitate energy flow: For me, it's food-energy in, then that energy is lost during thinking, feeling and moving.
These very thoughts you're reading, then, are my own lightning, my own upward billowing cumuli, my own shimmering warmth.
At dawn the next morning, cross-legged facing the sea with its towering columnar cumuli red-edged by the sun behind them, all around me crabs confidently and unthinkingly returned to their holes in wet sand. But, I had to consciously compose and analyze the illusion of a man with a tent needing to be vacated, before I could get up and do just that.
Best wishes to all Newsletter readers,
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