JIM CONRAD'S
NATURALIST NEWSLETTER
Issued from Diego Nuñez's office above
Restaurante "Isla Contoy," Río Lagartos, Yucatán, MÉXICO

November 13, 2006

MY MORNING WALK
Though Río Lagartos offers all you could want in color, friendliness and tropical musicality and exoticism, in the end it's still a congested little town crammed onto a small peninsula jutting into the estuary, and I still have hermit, country tendencies. Therefore, each morning, first thing after my run, I take a long walk through the mangroves.

At first glance the road, the estuary and the mangroves look just as they did the day before. Once I pay attention to which species are present and what those species are doing, however, big differences become apparent. I haven't been here long enough to recognize cycles but I assume that if I should stay awhile it'd be the cycles that would attract me.

Maybe on a certain day, perched atop a former pier's legs emerging from the water, there'll be a pure flock of Royal Terns. Then the next day maybe about a third of the flock will be composed of Sandwich Terns, with a Common Tern or two as well. Then the next day it may be all Royal Terns again.

It's similar to how most of the time you only see small, local fishing vessels anchored offshore but then one morning you get up and there are larger, different- looking ships out there from ports all along the Yucatan coast. This happened last week, and at dusk I enjoyed sitting on the storm wall watching the crews on those usually-hangdog-looking ships fixing barbeque-like suppers on their open decks, and sometimes piling into rowboats and going visiting neighboring crews. I was told that those ships were riding out a passing storm I saw no indication of.

Maybe my pier-leg tern population fluctuations reflect similar big events I can't detect. Or, maybe the fluctuations are just random. In the end, each pier-leg gets its tern, and on a certain day if a tern can't find a perch it just goes someplace else, and this happens no matter how majestic the events of broader workings.

In the mangroves here, these are birds you can depend on seeing every day: Little Blue Herons, Tri-colored Herons, Snowy Egrets, Great Egrets, White Ibises, Wood Storks, Roseate Spoonbills, Yellow-crowned Night Herons, Semipalmated Plovers, Spotted Sandpipers and Willets. Sometimes species show up not seen on days before. One day it was Least Sandpipers -- dozens of them all over the place mingling with Semipalmated Plovers as they daintily and nervously waded in the swamp's shallow water, jabbing their short, thin bills vertically into the alga-matted mud below.

Earlier I've reported how, inland, waves of migrant species, particularly overwintering warblers, appear and disappear through the season. I assume the same thing is happening with wetland migrants among the mangroves.

Speaking of mangroves, I've fixed up a nice page explaining why they're so important, diverse and fragile, plus you can see pictures of the four mangrove species any decent mangrove in this part of the world is supposed to have. You can take a look at the new page at http://www.backyardnature.net/yucatan/mangrov2.htm.

*****

LEAST SANDPIPERS
Those Least Sandpipers amaze me. Actually they're not very flashy birds, especially nowadays wearing their drab, brownish-gray winter plumage. They're only about 4-¾ inch long -- half an inch shorter than a House Sparrow. You can see a small flock at http://www.monterey-bay.net/birds/least_sandpipers.htm.

What amazes me about them is that they nest in a fairly small part of Alaska and Canada's northernmost coastline, yet during the winter they spread over an enormous area, from the southern US and the West Coast all the way to Peru and central Brazil. Moreover, throughout their winter distribution area they're often pretty common. The summer nesting area seems impossibly small for producing so many birds for such a large and densely populated overwintering zone.

I read that Least Sandpipers occur in Mexico from mid- July through May, which is 10-½ months. That doesn't seem to give them much time for nesting. However, in the far north they don't have much time.

Trying to fit together in my mind how all these summer and winter maps, and arrival dates and departure dates relate, I visualize waves of these little birds converging on their northern nesting grounds en masse, creating a veritable local blizzard of Least Sandpipers, then there's a rush to get through nesting and fledging, and finally a rush to leave, maybe as the first snows fall.

Why don't Least Sandpipers breed along the US Gulf Coast, or here, instead of so very far north? I can't see that the stuff they'd peck from tidal basins along the Gulf Coast in summer would be much different from what they get now, here. One thinks in terms of their nesting so far north to escape competition for resources from other birds, but if escaping competition is such a concern then why do such huge numbers concentrate in such a small nesting area?

Who knows why Least Sandpipers are as they are? Maybe the last ice age or a now-extinct competitor is responsible for the species' migratory dynamics, or maybe it all can be boiled down to a mathematical formula showing that their migration strategy is the most energetically efficient for them. Eventually someone will figure it out.

*****

GAUMER'S MAMMILLARIA
The single road running into Río Lagartos comes up exactly from the south. Houses at the edge of town extend into the mangroves, at high tide having water lapping against their foundations. South of the mangroves there's an amazing transition zone where you can see glossy- leafed, sprawling, wetland mangroves standing next to scrubby, spiny, arid-land plants typical of inland northern Yucatan.

What's happening is that wherever saltwater occasionally floods the almost-flat, very-slightly undulating land, even if only during the rarest high tide, mangrove gets established. But just beyond that high-tide mark -- and that can be only a couple of feet away -- then the vegetation mainly reflects climate, not tides or soil salinity. And the northern Yucatan's climate produces scrub. You can see how deserty the vegetation can look, even when standing only a few feet from mangrove swamp, at http://www.backyardnature.net/n/06/061113s.jpg.

In the above picture I think the broadleaf bush with a pale, semi-succulent trunk is a Jatropha, possibly J. gaumeri. The grayish-green, long, slender, leafless stems are Pedilanthuses, probably P. tithymaloides. You may recognize a young Agave, and I assume that the arching, four-ribbed cactus is Acanthocereus pentagonus.

This glimpse of the scrub zone's exotic nature may help you imagine my frustration that no field guides are available to help me identify plants here. The problem is especially aggravating because so many of these arid-land species are endemic -- found nowhere else on Earth. Plant endemism has been estimated to reach nearly 10% of the Yucatan's Dry Forest vegetation. Northwestern Yucatan, the most arid part, is home to 10 of the Peninsula's 14 endemic cacti species.

The other day I was walking along the road running north to Río Lagartos, passing through the scrub zone, when Diego pulled up beside me in his car.

"Want to see Mammillaria gaumeri," he asked, knowing full well I'd be thrilled. Mammillaria gaumeri is one of those rare, narrowly endemic species that would delight any naturalist.

We found it growing not 50 feet from the highway, right along a trail Diego uses for his birding walks. You can see my picture of the ten-inch-high specimen at http://www.backyardnature.net/yucatan/mam-gaum.jpg.

I have no way of knowing for sure that this really is the endemic Mammillaria gaumeri since it's not flowering and I don't know what distinguishes the species from other Mammillarias. A specialist told Diego it was Mammillaria gaumeri and now Diego has told me. I'm sure it's a Mammillaria, and the Flora of Quintana Roo -- the state just east of here -- lists only one Mammillaria species for that state, and that's gaumeri, so probably it is.

Mammillarias are easy to identify as a group because their more or less spherical cactus bodies are composed of many protruding green bumps -- like a lot of green chili peppers packed together so their roundish bottoms face outward. The botanist who named the genus was thinking in terms of lots of round teats, thus the name Mammillaria, from the Latin "mamila," meaning "nipple- like."

If you want to learn about just one, easy-to-recognize cactus group, the genus Mammillaria makes a good choice. A website for learning all about the genus is at http://www.mammillarias.net/index.php.

By the way, here in the northern Yucatan I'm constantly running into unusual plants bearing the species name "gaumeri." Earlier we had Jatropha gaumeri. "Gaumeri" is the Latinized form of the name Gaumer. George Franklin Gaumer (1850-1929) was a US citizen residing in the Yucatan from 1884 to his death, and he collected a remarkable number of rare and endemic species, which he sent to specialists for identification or, if they were unknown to science, for naming. Many of those specialists named the undescribed plants after their discoverer, Gaumer. There's Acacia gaumeri, Caesalpinia gaumeri, Thevetia gaumeri, Vitex gaumeri, and many more.

What a heck of a lot of fun that guy must have had as he explored a land basically unknown to biologists!

*****

GIANT LEATHER FERNS
South of town, waterlogged mangrove doesn't always give way just to thin-soiled, cactus-rich, desert scrub. In some places mangrove yields to grassy marshes -- clumps of grass rooted in mud, with soil between clumps either submerged beneath saltwater or soaked. Often, even in this important, officially recognized "Biosphere Reserve," cattle graze these marshes.

Sometimes Giant Leather Ferns, ACROSTICHUM DANAEFOLIUM, emerge from the soggy grassland. Taking in their effect, one might say "emerge like a Viking on a beach." In fern terms, these are huge, coarse-looking things giving the impression of having been rooted exactly where they are since dinosaur times. You can see one such fern, with fronds soaring nearly nine feet (2.5 m) above the muck at http://www.backyardnature.net/yucatan/acrostic.jpg.

In the above picture the inset on the right shows a close-up of the fern's fertile pinnae. There you can see that this species produces its dusty, cinnamon-colored spores not in dainty clusters of spore-producing sporangia, like the North's little Woodsias and Shield Ferns, but rather they are randomly and abundantly spread across the entire lower surfaces of fertile pinnae.

Actually there are two species of Acrostichum fern found in places like ours, and I bet the other one, A. aureum, called Mangrove Fern, Golden Leather Fern, Swamp Fern and a host of other names, is found here, too. The "Flora of Quintana Roo" lists both species.

Speaking of that "Flora of Quintana Roo," which was written in Spanish and gives plant names in Latin, sometimes when you know what a plant's family or genus is it's helpful to have a list of species known to occur in the families and genera of the area you're studying, or next to. For example, I knew from experience that I had a Pedilanthus in the Mammillaria habitat shown above, but I had no idea which Pedilanthus it was. The "Flora of Quintana Roo" listed only Pedilanthus tithymaloides for that contiguous state, it looks like that species when I Google it, so a good guess is that what's shown in my picture is that species.

The "Flora of Quintana Roo" can be downloaded at http://biblio68.ibiologia.unam.mx/FullText/lfl2.html.

*****

SEAGULL-EATING PEREGRINE FALCON
Friday I heard from my old friend Sandro. When he needs money he signs on as a crewmember on a big fishing trawler in northern waters. He wrote that, apparently because of global warming, during this last fishing season his ship had fished exceptionally far north -- "about 60/90 miles off Cape Navarin Russia just north of the peninsula of Kamtchaka."

Then he told me how one day the crew started talking about "some kind of hawk or a falcon eating seagulls on the bow... I observed the pajarito everytime I had a chance, and boy let me tell you that he kept a full belly, all he did was hunting and go eat on top of one of the spare nets that we had on the bow, this lasted for about 5 days and then he left."

Sandro managed to get a snapshot of the seagull-eater smugly perched on a heap of netting, and he sent the picture to me.

It was an immature Peregrine Falcon, an Arctic subspecies. I showed the picture to Diego, Río Lagartos's master bird-guide, expressing my surprise that any raptor would eat a seagull. Diego said that Peregrine Falcons overwinter here, he's already begun seeing this year's crop, and he's seen them attack seagulls here.

"In mid-air he hits into the gull with his shoulder, then before the gull can get its balance the falcon has circled back and put its talons into it."

I've seen Peregrin Falcons referred to as "the planet's fastest animal," and I've seen what a blur they are when they pass by, so I have no doubt that they could take advantage of a clumsy old seagull suddenly shouldered out of the sky.

*****

CHECKERED PUFFERS
For me the most attention-getting fish easily and habitually seen almost anytime I go walking along the storm wall or look into the shallow waters between boats tied up along shore is the Checkered Puffer, SPHOEROIDES TESTUDINEUS. You can see one, maybe 10 inches long, here.

That image shows a heavily spotted, big-headed, thick-bodied fish with bulging, froglike eyes. The fish in the picture is lying on the bottom, but the ones I see are always unhurriedly swimming along, so exposed to the world you have to guess that they possess some kind of secret weapon. I have no fish books so to get a name I had to ask a kid.

"Pez Globo," the boy said, absolutely amazed that a huge, bald gringo would simply walk up and ask something like that. The name means "Balloon Fish," and I said I couldn't see anything about it that reminded me of a balloon.

"When the fish gets scared, he blows himself up, all at once, like this, a GLOBO..."

Later I spoke with a fisherman and asked him whether that clumsy looking fish happening to be swimming by really was a Pez Globo.

"Yes, and we sell them to the Japanese. The Japanese eat everything from the water other people don't eat, even these, which are so poisonous. Yes, POISONOUS. You have to prepare the fish very carefully because if poison from the poison gland gets onto what you eat it'll kill you. In Japan they make people who order it sign a legal paper saying they've been warned and if they get sick or die the restaurant isn't liable, and still people want to eat it!"

The fish's poison is one known technically as a saxitoxin. In some places the fish has been used to kill dogs and cats and in Haiti it's been documented as an ingredient in a potion concocted to turn people into zombies. If you want follow up on that, go to http://www.flmnh.ufl.edu/caribarch/zombi.htm.

So, being able to blow yourself into a balloon too big to fit between a predator's jaws, and having a poison gland that can kill enemies or maybe turn them into zombies -- no wonder this fish of all the estuary's species feels so at ease that it can swim in broad daylight in shallow water next to shore!

Up North English speakers call the fish Checkered Puffer, and the species is found all along the Gulf Coast and a good deal north along the Atlantic Coast. Southward it extends all the way to Brazil.

I've only seen Checkered Puffers try to catch immature, big-eyed shrimp moving along the storm wall but I read that the species eats bivalves, gastropods, foraminiferans and several other invertebrates, including it's main meal, crusty crustaceans like my shrimp, which it crushes with powerful teeth.

*****

BAKING TAMALES IN A PIT
On Thursday morning I was walking to the famous freshwater swimming hole just east of town when I saw several men very busy around a large hole in the ground maybe 20 feet from the mangroves, and with a good view of the estuary to the north. Smoke rose from the pit. I figured I was seeing the traditional method of preparing a special, oversized tamale in earthen pits, so I just had to walk over and make the acquaintance of these men. When I got there I could see that they'd just gotten a small fire going and were about to add larger chunks of dried wood.

"Once we have a big fire, then we pile on these rocks and make them very hot. Right now the señora is at home making tamales. Later today when the rocks are as hot as they can be we'll bring the tamales and spread them over the rocks, and cover them to keep the heat from escaping. About sundown, then we'll come and remove the tamales."

I asked if I could come, too, and see what it all looked like.

I arrived as the sun was setting and an older couple and a young man were just removing the palm fronds and a large, quadrangular, metal plate from above the pit. Actually the pit had been fairly well camouflaged and I wondered what might have happened if I'd been there chasing a bird, not paying much attention to where I stepped, and suddenly made the acquaintance of that hot little pit. Anyway, you can see how it was immediately after the metal plate was removed, with the plate lying in the background and the pit absolutely crammed with tamales wrapped in palm fronds and baked to perfection at http://www.backyardnature.net/n/06/061113t.jpg.

Another shot showing how they also were baking "camotes," or sweet potatoes, in aluminum foil, as well as some hard-shelled squash, is shown at http://www.backyardnature.net/n/06/061113u.jpg.

The palm fronds wrapped around the tamales are similar to thatch fronds used for roofing buildings, except much smaller. Thatch Palms have regular trunks but these are a trunkless, palmetto-like species, maybe Thrinax radiata.

I was offered one of these special, oversized tamales, which the locals call "chachacua" in Yucatec Maya, and then there was the awkwardness of explaining my vegetarianism. However, I still walked away with a fine, foil-wrapped camote.

The wandering sprits then took their revenge on me for my culture having made the Day of the Dead -- which these chachacua were being baked to celebrate the end of -- into something as void of meaning as Halloween. For, I was so pleased with my very hot sweet potato that I bit off too much. Somehow it didn't burn my mouth at all but when it hit my stomach is caused a burning pain more intense than I've experienced in years. And there was nothing to drink. I tried to induce saliva and swallow, but of course my mouth had gone dry. It hurt so badly that I actually started running toward the estuary with plans to drink what I could of that sewage-rich brew, and I'd have done so if the storm wall's top hadn't been so high above the water.

In the end I just lay atop the wall until the misery passed and it was dark, and then I ate my camote more intelligently. From the grimmace on my face passersby might have judged me a philosopher wrestling with decades-accumulated Weltschmerz, but, really, there was nothing going on there but a sweet-potato bellyache.

I don't hear of things like this happening to other 59-year-old people. Sometimes I wonder how I've made it this far.

*****

Best wishes to all Newsletter subscribers,

Jim

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