JIM CONRAD'S
NATURALIST NEWSLETTER
Issued from Mayan Beach Garden Inn 20 kms north of Mahahual
on the Yucatán Peninsula's eastern coast just north of the Belize border,
in the state of Quintana Roo, MÉXICO
(N18°53'17", W87°38'27" )

May 1,  2011

I'VE MOVED
Last Monday morning I broke my usual routine. I piled things into a pickup truck and left Hacienda Chichen next to the Maya ruins of Chichén Itzá, where I've lived contentedly for the last year and a half. Unless plans change, for the next six months I'll be writing from Mayan Beach Gardens in southern Quintana Roo State, in the southeastern Yucatán Peninsula, not too far from the border with Belize. You can see Mayan Beach Gardens' web pages, with many interesting links, at http://www.mayanbeachgarden.com/.

Around October probably I'll return to Hacienda Chichen, the hut and my friends there, with whom I've become quite close. I do appreciate the generosity and friendship of the Hacienda's owners and employees more than words can say. While there I've certainly received much more than I can ever give.

But, now let's start looking at things here in the coastal environment.

*****

MY NEW LOCATION
Actually, we've been here before. The six Newsletters issued between December 1, 2008 and January 5, 2009 came from Mayan Beach Gardens. Already we've described the general landscape here, and profiled the dominant species. Here's a brief review:

First, if you have Google Earth, do a search for "Mayan Beach Gardens Yucatan" and you'll see that we're exactly on a beach facing the Caribbean. The shallow, blue waters immediately offshore are home to endless "prairies" of Turtle Grass, Thalassia testudinum, which we've looked and photographed at http://www.backyardnature.net/yucatan/thalassi.htm.

Here and there the Turtle Grass gives way to Shoal Grass, Halodule wrightii, examined at http://www.backyardnature.net/yucatan/shoal-gr.htm.

Mayan Beach Gardens and some private residences occupy a rather low, narrow ridge of white sand wedged between the Caribbean to the east and extensive mangrove swamps to the west. During the next six months we'll see and do many things in the mangroves, and the mangroves are enormously important to regional ecology, so you may want to review our mangrove page at http://www.backyardnature.net/yucatan/mangrov2.htm.

On our narrow sand ridge, species diversity is low but the species present are highly adapted to our special environment -- sand instead of soil, and sand and air with lots of salt in it.

The main trees are Coconut Palms and Chit Palms. You know what Coconut Palms look like. Our Chit page is at http://www.backyardnature.net/yucatan/chitpalm.htm.

Other ubiquitous and conspicuous plants include Seagrapes, Coccoloba uvifera, presented at http://www.backyardnature.net/yucatan/seagrape.htm.

Also there's the silvery- and fuzzy-leafed shrub sometimes known as Sea-Lavender or Sea-Rosemary, Tournefortia graphalodes, described at http://www.backyardnature.net/yucatan/sealaven.htm.

Sometimes you see sizable populations of Coastal Spiderlily, Hymenocallis littoralis, shown at http://www.backyardnature.net/yucatan/hymenoca.htm.

Few spiderlilies are flowering, but plenty of large, purple blossoms of the Goat's-foot Morning-Glory, Ipomoea pes-caprae, adorn extensive vines running across the sand, as seen at http://www.backyardnature.net/yucatan/goatfoot.htm.

The sand is wonderful to walk barefoot in, except for the Coastal Sandburs, Cenchrus spinifex, profiled at http://www.backyardnature.net/yucatan/sandbur.htm.

The most conspicuous birds right now are Magnificent Frigatebirds who sail down the beach looking primitive and menacing in the sky, Tropical Mockingbirds at the mangrove edge and Yucatan Jays flitting among the resort's palms.

And now, let's begin looking at the other things...

*****

SIAN KA'AN BIOSPHERE RESERVE
One reason I returned to Mayan Beach Garden is that it's within bicycle-riding distance of Sian Ka'an Biosphere Reserve, which is 1.3 million acres (528,147 hectares) of protected natural area. It's a World Heritage Site. Last Monday, Bruce, co-owner of Hacienda Chichen, not only trucked me to my new location but also the following morning drove us into Sian Ka'an.

You can see a typical stretch of the sand track we took along the beach to road's end at Punta Herrero at http://www.backyardnature.net/n/11/110501sl.jpg.

A typical view of the seemingly unending beach is at http://www.backyardnature.net/n/11/110501sk.jpg.

A brief overview of plants, animals and ecosystems to be found within Sian Ka'an reserve is provided at http://whc.unesco.org/en/list/410.

About 339 bird species have been recorded within the reserve, as well as 103 species of mammal, including five species of cat -- jaguar, puma, ocelot, margay and jaguarondi. Other mammals include Central American Tapir, Caribbean Manatee, Spider and Howler Monkeys, Kinkajou, White-tailed and Red Brocket Deer, White-lipped Peccary, Paca, Tayra and Collared Anteater.

Often we've stated that in the Yucatan it's rainiest and therefore the vegetation is most lush, and species diversity is the greatest, in the southeast. The farther northwest you go, the drier it gets, until in the extreme northwest, around Sisal, the woody vegetation is very low, scrubby and spiny. At Hacienda Chichen we were in the central Yucatán. Now we're down in the rainy, lush area, where we'll see species not to be encountered farther into the less rainy northwest.

*****

LATE LAUGHING GULLS
During my earlier, winter stay at Mayan Beach Garden seagulls commonly ranged up and down the beach the whole day. This time there were none. When I thought about it, it made sense, though, because the main gull here, the Laughing Gull, is only a winter visitor. You can see the Laughing Gull's winter plumage at http://www.backyardnature.net/yucatan/gull-laf.jpg.

Sian Ka'an's southern entrance road ends at Punta Herrero, a fishing village of about fifty, at the very tip of a long peninsula. There we found two Laughing Gulls in their black-headed breeding plumage, shown at http://www.backyardnature.net/n/11/110501gu.jpg.

In A Guide to The Birds of Mexico and Northern Central America Howell describes Laughing Gulls as winter visitors in this area from September through April. Last Tuesday was pretty late in April, so the gulls in the picture surely were just resting during their passage northward. The species overwinters as far south as northern South America, so the birds in the picture well may be part of the southernmost population, maybe fresh off the beaches of Venezuela or Columbia.

These might be the last gulls I see all summer, for no gull species regularly breeds during the summer along the Yucatan's coast. It's about the same situation with similar-looking terns -- all tern species leaving the Yucatan during the summer, though small numbers of a species or two may remain nesting in certain isolated spots, as on islands.

So, this is a curious feature of this beach during the northern summer -- the conspicuous absence of gulls and terns.

*****

CAST NETTING FOR "SARDINES"
Up the beach I ran into an old guy with a bucket and a net. He said he was going to catch Sardinas to use as bait. Spotting my camera, he told me to watch and take pictures "para su reportaje," "for your report." I guess he has figured out that the reason we gringos take so many pictures is that we're all doing reports. With his net under his arm he waded into the shallows, straightened out his net, walked around gazing into the water like a stork, and then suddenly he cast his net, and you can see my report for that pretty moment at http://www.backyardnature.net/n/11/110501sb.jpg.

He needed only one cast. The old guy is showing off at http://www.backyardnature.net/n/11/110501sc.jpg.

Up on the beach he tossed his catch before me, seen at http://www.backyardnature.net/n/11/110501sa.jpg.

A close-up of a single fish is shown at http://www.backyardnature.net/n/11/110501s~.jpg.

A conspicuous field mark for this species seems to be that reddish-orange spot behind the eye. Back at Mayan Beach Garden's little nature library I dug out Humann and Deloach's Reef Fish Identification: Florida Caribbean Bahamas and, looking for a small, silvery fish with a reddish-orange spot behind the eye, soon matched my "Sardinas" with a picture.

It looks like the fish are Redear Herrings, sometimes called Redear Sardines, HARENGULA HUMERALIS. Plenty of pictures of the species appear on the Internet but there's not much information about them, other than that in shallow water they swim in dense schools and are much sought after as bait. One study finds that they reproduce year round, but mostly from January to August.

*****

ICACO
On Wednesday morning some visitors needed to be dropped on the beach in Sian Ka'an so they could beach-hike for about ten miles, then be picked up later, so I rode up with Marcia, co-owner of Mayan Beach Garden. You can see Marcia -- who you'll hear about a lot because she knows so much about this area -- standing beside an interesting bush found there at http://www.backyardnature.net/n/11/110501ic.jpg.

In English the bush is called Icaco or Cocoplum. It's CHRYSOBALANUS ICACO, a member of the Chrysobalanus Family, little known to Northern nature lovers, because its approximately 460 species in 17 genera are restricted to the American tropics and subtropics. The family is close to the Rose Family.

The eye-catching feature about this bush was that it was loaded with plum-size, white fruits, as seen at http://www.backyardnature.net/n/11/110501id.jpg.

The white one was mature and rather nice to eat. White, sweet, melon-textured flesh surrounded a large seed. If you're hot and hungry while hiking the beach, you'd welcome finding this bush heavy with fruits. In fact, I hear that the fruits make a fine jam.

Among the fruits there were a few tiny blossoms, shown at http://www.backyardnature.net/n/11/110501ie.jpg.

That picture is interesting because it shows two blossoms side by side, but the flowers are different. The older, fading one at the left bears numerous male stamens -- the items with slender filaments (stems) topped with oval, pollen-producing anthers. However, on the younger flower at the right, there's no sign of stamens. In that flower's center you see a round-topped, pollen-receiving stigma atop a slender style leading down into the flower, to the ovary nestled there like an upright egg in a bowl.

Bearing two such different flowers is possible for Icaco because the bushes can be "hermaphroditic, or andromonoecious, or gynomonoecious." Hermaphroditic plants are those on which all flowers bear both male and female parts. Andromonoecious plants bear both bisexual and strictly male flowers on the same plant. Gynomonoecious plants bear both bisexual and strictly female flowers on the same plant. It looks as if our flower picture shows a plant that's gynomonoecious, because the flower on the right is strictly female, while the older flower on the left appears to bear both male and female parts.

I searched for studies explaining how such a curious sexual orientation could be adaptive for an organism, but it appears that no one really knows. Lots of theories, but no clear experimental results.

Icaco is native from Mexico to northwestern South America, as well as the Caribbean and tropical western Africa. It's been naturalized in several places in Asia and Oceania.

*****

LETHAL YELLOWING DISEASE IN SIAN KA'AN
As Bruce and I traveled through Sian Ka'an we saw many dead and dying palms, but we weren't sure whether they were diseased, or damaged by Hurricane Dean, which devastated this area in January of 2008. On my trip up the next day, Marcia told me, because scientists studying the situation stay at Mayan Beach Garden, and tell her all about it.

On the Web an author with the United Nations Environment Program writes that during the ten years between 1998 and 2008, 95% of Sian Ka'an's Coconut Palms were destroyed by Lethal Yellowing Disease, often known as LYD. The main reason for such a disastrous decline is that over the years people had replaced native ecotypes of relatively slow-growing Coconut Palms producing odd-shaped and often smaller coconuts, with a fast-growing kind producing very large, spherical coconuts. So, at the root of the problem is displacement of diverse, native Coconut ecotypes with a monoculture.

You can see a typical Coconut Palm dying of Lethal Yellowing Disease in Sian Ka'an at http://www.backyardnature.net/n/11/110501y0.jpg.

A close-up of a typical infected frond is shown at http://www.backyardnature.net/n/11/110501y3.jpg.

LYD is caused by a special kind of bacteria known as a phytoplasma. Phytoplasmas were unknown to science before 1976. They live only in plant phloem -- phloem being the part of a plant's vascular system transporting photosynthesized glucose and other organic nutrients to all parts of the plant. The phytoplasma disease organism is transported from plant to plant by common, piercing-and-sucking insects known as planthoppers.

In Sian Ka'an it's often the case that palms weakened by LYD are attacked by a very large beetle, the Palmetto Beetle, Rhynchophorus cruentatus, whose grubs tunnel through palm-trunk centers, killing the palms faster than if only the disease were involved. As we drove around, Marcia showed me how to distinguish between palms dead and dying from LYD, and those killed by beetles attacking trees weakened by LYD. Those dying strictly from LYD first lose their lower fronds. Dead fronds surround the trunk while yellow to greenish fronds rise in the center, as shown at http://www.backyardnature.net/n/11/110501y0.jpg.

Palms killed by beetle grubs die from the inside-out, all fronds collapsing together, as pathetically shown at http://www.backyardnature.net/n/11/110501y2.jpg.

At least 36 palm species have been documented suffering from LYD, and the Chit Palm, the other abundant palm, a fan palm, so characteristic of this area, is one of those vulnerable to the disease. However it seems to be more resistant than Coconut Palms.

Needless to say, anyone planting Coconut Palms should avoid using the fast-growing variety producing large, round coconuts. Instead, native ecotypes that may be slower growing and producing small, irregular-shaped coconuts should be chosen.

*****

SEASIDE GENTIAN
I'm on a narrow sand ridge between the ocean to the east and extensive mangrove swamp to the west. Organisms occupying this sand-ridge environment deal with extreme environmental conditions -- sizzling heat, dazzling sunlight on white sand, sand through which rainwater drains very quickly leaving very dry rooting conditions, and everything is salty.

A knee-high plant flowering nowadays not looking nearly tough enough to survive such extremes is shown at http://www.backyardnature.net/n/11/110501bb.jpg.

A close-up showing the spectacularly patterned interior of a two-inch-across (5cm) flower is at http://www.backyardnature.net/n/11/110501bc.jpg.

This pretty member of the Gentian Family, common along roadsides, is native not only to much of Mexico, the West Indies and parts of South America, but also to the US where it's found from Florida west to California and north in the interior to Montana and South Dakota. Since it's so eye-catching, it goes by many common English names, including Catchfly Prairie Gentian, Showy Prairie Gentian, Bluebell Gentian, Western Blue Gentian, Blue Marsh Lily, Small Bluebell, Catchfly Gentian, Catchfly Prairie-Gentian, Beach Gentian, Seaside Gentian and in Texas of course they call it the Texas Bluebell. Since here we're on the beach, I'll call it Beach Gentian. It's EUSTOMA EXALTATUM.

Though it's in the Gentian Family, it's not really a gentian. To be a gentian it'd have to belong to the genus Gentiana, but you see that it's in the genus Eustoma.

Not only is Beach Gentian widely distributed, but also it's highly adaptive, living in sandy coastal areas such as ours as well as moist places in prairies and fields, and saline to freshwater marshes.

*****

ALIVE ON THE BEACH
At this new location you always hear waves breaking on the sand beach. In slow motion clouds come ashore, sometimes sharply defined, sometimes just vague curdles, but always moving, regrouping, coming and going. Nearly always a stiff breeze flows through the windows of my second-story room facing the sea.

Outside the window, always you see white-capped waves moving shoreward and, beneath the window, the tops of young palms and Tropical Almonds gyrating in wind. Walking along the beach, sand peppers your ankles, salt spray fogs your glasses and Frigatebirds float above you. Movement, movement, movement.

All that interminable movement affects the nervous system. It's not that it makes one nervous, but it does create in the spirit a kind of raw edginess. It's not unpleasant, but maybe it is a little intoxicating, even addictive. That's OK. It's OK like falling in love knowing that it'll all end soon. But, somehow you want, you need, the flowing, the churning, the blowing and breaking, the movement, even when you know about the hurt soon to come.

From experience I know that when finally I have to go far enough inland to not hear the surf, not feel wind off the water, where Frigatebirds don't hang in the sky, I'll feel some kind of void, an emptiness, the tragic end of something. Dumbly I'll sit or stand wondering what will take the place of all that obsessive, distracting agitation.

But, for now, I don't have to worry about that, for I'm in the midst of it all, addicted, obsessing, alive on the beach.

In fact, these days and nights, I do herby exquisitely consciously and with utmost purpose declare my determination to exult in rawness of wind-blown wave- foam, edginess of Frigatebird silhouette in dazzling sky, do set forth my sweaty leg for windblown sand to stick to, do suck deeply this salty, fish-smelling wind and take it into me so hungrily and violently that it flaps my jowls and whistles down my throat into bottomless me.

Well, at some point on every beach walk you turn toward the ocean where it's deepest and there, long and long, you stand staring, so vividly alive.

That's where we're at right now.

*****

Best wishes to all Newsletter subscribers,

Jim

All previous Newsletters are archived at www.backyardnature.net/n/.

Visit Jim's backyard nature site at www.backyardnature.net