April 28, 2007
MOJARRA THE AQUATIC CHICKEN
Last Sunday morning a little after sunrise I was down below the dam's overflow sluiceway atop a limestone rock next to a little pond that was emerald green with algae. It was a peaceful, lush oasis surrounded by steep, scrubby slopes heating up fast. Cicadas droned on and on upslope.
Then two young men, Marciel and Ernesto, emerged from behind some bushes carrying two fish on a string, which they lay on the grass next to me. The fish, whose tails were attractively banded, differed from carp or bass in that their top fins, the dorsal fins, arose right behind their heads and ran continuously almost all the way to their tails, where they were actually at their longest. I asked Maraciel if the fish were tilapia. He looked a bit confused and said that they were Mojarra (mo-HARR-ah, the rr trilled). You can see the two fish lying in the grass next to me at http://www.backyardnature.net/n/07/070428mt.jpg.
When I got back to my computer I compared my picture with what I could find with Google and figured out that both Marciel and I had been right, for the Spanish name for the fish is Mojarra Tilapia. They're TILAPIA NILOTICA.
This is a famous species, nowadays grown worldwide in prodigious numbers and sold in so many restaurants that they're sometimes called "aquatic chickens." Native to eastern Africa, development agencies such as USAID and the World Bank have pushed so hard for the spread of tilapia farming that now the species is grown in more than 85 countries. Because big money is involved there's so much hype about the species that you don't know what to believe. A review of the situation is at http://www.treehugger.com/files/2005/03/aquatic_chicken_1.php.
You can see a large tilapia farm in Arizona at http://www.desertspringstilapia.com/desertspringstilapia-en/index.htm.
Interesting points made at the above site are that Tilapia nilotica is 98% vegetarian, can live in either fresh or brackish water, can thrive on agricultural waste, and grow rapidly in hot temperatures. They must be tough fish to do so well in the alga-green pool below the dam where the oxygen level surely drops low at night, and I'll bet that there's plenty of agricultural chemical runoff in the water, too. Environmentalists are concerned that in warm areas introduced and escaped tilapia may crowd out native species.
As I took my picture Marciel stripped to his shorts and waded into the water. Briefly he submerged and came up with a string of four more Mojarra Tilapias, which earlier he'd tied to an underwater tree stump for safe keeping. Then he waded to another submerged stump and came up with yet another string. You can see what Marciel looked like emerging with his fish at http://www.backyardnature.net/n/07/070428mm.jpg.
Marciel says that our reservoir is full of tilapia, carp, bass, catfish and trout, all introduced species. I'd always considered this area as too hot for trout but if you look closely at the string in Marciel's right hand (our left) you'll see a fish he called trucha, which is trout, and it sure does look like a Rainbow Trout.
Marciel explained that late Saturday he'd strung a gillnet across the pond. Fish try to get through the net, can't make it, start backing out, but can't, and get the net stuck in their gills.
When Ernesto started walking away carrying the strings one string came undone, his catch plopped onto the ground, and his biggest tilapia flopped into the water and swam away. I was glad for the tilapia but when I saw the look on Ernesto's face I felt sorry for him, too.
SPLASH OF THE GREEN KINGFISHER
Right before Marciel and Ernesto came along, I'd been rather abstractedly communing with the pond ecosystem, and more than once just a few feet away I'd heard a small splash as if someone had tossed a pebble into the water. When I'd looked in that direction, however, what I'd seen had been a little Green Kingfisher the size of a Hairy Woodpecker flying away. You can see a Green Kingfisher at http://www.worldbirdingcenter.org/bird_info/green_kingfisher.phtml.
Green Kingfishers are a little more than half the size of North America's Belted Kingfisher. Anyone used to the Belted's spectacular splatterings when diving for fish will be struck by the Green's much more modest little ker-plunk. It's clear that the physics of a small bird diving into water differs a lot from that for a big one. It's as if water becomes thicker for smaller birds, and therefore harder to penetrate. If you extrapolate the concept on downward you come to insects walking atop water.
Green Kingfishers are by no means Mexico's smallest kingfisher species. The Green is ±7.5 inches long but the Pygmy of southern Mexico and the Yucatan is only ±5.5 inches (20 & 13 cm, respectively). At Río Lagartos occasionally I saw Pygmys in the mangroves. Mexico is home to five kingfisher species, and one, the Ringed, is noticeably larger than the Belted common in much of North America. Our Green Kingfisher occurs from southern Texas all through Mexico and Central America to northern Chile and Argentina. Along the Amazon's steamy banks the Green Kingfisher is hard to miss.
Actually, relative to the rest of the world, the Kingfisher Family is poorly represented in the Americas, which hosts only six species. The part of the world richest in kingfishers is the Australasian Region, followed by Africa and Asia. Not all kingfishers dive into water for fish. At http://animaldiversity.ummz.umich.edu/site/accounts/information/Alcedinidae.html I read that "About 44 species live in closed-canopy forests (primary and secondary), 17 species in wooded savannas, and 31 species in aquatic habitats including seashores, mangrove swamps, lakes, rivers and streams. One species lives in desert scrub."
There's a lot of life-history information about kingfishers at the above address, too.
AQUICHE AT ITS UGLY TIME
Early this week I accompanied a group of foreign visitors on a late-afternoon hike down the reservoir road. One plant that really got that group's attention was the Aquiche. For one thing, Aquiche is probably our second-most abundant roadside tree, after the Sweet Acacia. For another, people just couldn't believe a tree could look so disheveled and ugly. The poor scraggly thing was mostly leafless, with only a few tattered, faded, bug-eaten leaves giving it a hang-dog look, and then it was absolutely loaded with black, bumpy-looking, hard, scratchy fruits. You can see what I'm talking about at http://www.backyardnature.net/n/07/070428g0.jpg.
You can see a close-up of some fruits in my hand at http://www.backyardnature.net/n/07/070428g9.jpg.
Actually, I've told you about Aquiche before, because also back in the Yucatan this was one of the most common roadside "weed trees." In the Yucatan the Maya call it Pixoy, and in other parts of Mexico it's often called Guácima. It's GUAZUMA ULMIFOLIA, a member of the same family the Cacao tree of chocolate fame belongs to, the Sterculiaceae.
Beneath many Aquiche trees nowadays the ground is thick with black fruits. When you approach such a tree on a hot, sunny day a strong honey odor hangs in the air. That's because the fruits are very slightly sweet. In sunlight you can see "honey droplets" glistening in cracks between the fruits' bumps. In fact, when you're real hungry you can actually eat the fruits, being careful not to break a tooth. Here Nature has done a masterful job making a fruit that's too hard for most animals to fool with, but just sweet enough to entice someone every now and then to gnaw on one. It's a lot like eating the crusty backbones of Honeylocust fruits. On the Internet I find a report of White-faced Monkeys eating Aquiche fruits in Costa Rica, but only infrequently.
Livestock eat the leaves and workable fiber can be drawn from the branches. My "Plantas Medicinales de Mexico" says that traditionally the tree's bark was used to cure malaria, skin diseases, elephantiasis, leprosy and other ailments.
Some trees loaded with fruits already bear little yellow flowers. Apparently it takes about a year for those tough fruits to mature.
Catching the foreign visitors' attention even more than the Aquiches were the abundant tufted clumps of epiphytic, or tree-branch-living, plants about 15 inches across, with grayish-green, grasslike leaves and long-stemmed, mostly red flower-clusters.
"Are they orchids?" people asked several times, apparently finding it hard to believe that such attractive, epiphytic plants wouldn't be orchids. In fact, until recently there were indeed plenty of yellow-flowering orchids -- the yellow-flowered Oncidiums I told you about in the March 24th Newsletter -- but it looks like someone has gone done the road collecting them. I didn't see a single orchid during our whole walk.
Anyway, the plant putting on our show was a bromeliad, probably TILLANDSIA SCHIEDEANA, a fairly common plant at this elevation from Mexico through Central America to Venezuela and Columbia. You can see one we looked at at http://www.backyardnature.net/n/07/070428tl.jpg.
In that picture the red items in the inflorescence are "bracts," or modified leaves, while the flowers are the slender, yellow things extending beyond the bracts. Bromeliad flower structure isn't like that of most garden blossoms.
If you see a tufted plant growing in a tree and its flowers are arranged in dense spikes, the blossoms themselves are small and inconspicuous but the bracts below the flowers are bright and colorful, a good guess is always "bromeliad." One way to avoid confusing epiphytic orchids with bromeliads is to remember that orchid inflorescences usually lack large, colorful bracts below each flower, and usually orchid roots attached to a tree's bark are thickish and white, while bromeliad roots are typically wiry and dark.
The Reserve's Management Program book lists 19 bromeliad species -- members of the Bromeliad Family, the Bromeliaceae -- of which 13 species belong to the genus Tilandsia.
What a treat to be walking down a road and see something as pretty as this Tilandsia simply growing in a tree next to you. But, what a pain that somebody has gone down that same road stealing the orchids from us all!
AN UNUSUAL BROMELIAD
This Wednesday I joined up with a group of Peace Corps volunteers receiving their orientation to the Mexican experience by visiting various communities in the Reserve area. Soon the volunteers will be dispersed throughout the country for two years of many kinds of service. During their two days here we visited projects, hiked and climbed.
On Thursday at San Juan de los Durán, Don Tacho guided us up the very steep trail behind San Juan's eco- bungalows so we could enjoy the view across the valley. It was hard to keep from slipping on the trail not only because of its steepness but also because dry oak leaves created a very slippery surface.
However, the view from the top was worth the trouble. You can see part of the group perched on the cliff-top's jagged limestone, with San Juan in the valley below, where with binoculars we could see a mule walking circles, pressing syrup from sugarcane stems, at http://www.backyardnature.net/n/07/070428sj.jpg.
In that picture, if you look in the lower, left corner, you can make out a cluster of red flowers. You can see a close-up of the plant issuing those flowers at http://www.backyardnature.net/n/07/070428pt.jpg.
Before I could analyze one of the flowers I thought the plant was a Lily-Family member, but soon I realized that we had another bromeliad. However, what a curious bromeliad this was!
First, as pointed out above, the vast majority of bromeliads are epiphytes -- growing on trees -- but this one was clearly rooted among limestone rocks. Second, unlike most bromeliads, the bracts below each blossom in the inflorescence were small and inconspicuous.
Though I can't find illustrations to match this plant, my guess is that it's PITCAIRNIA RINGENS, which has been identified in the area. The genus Pitcairnia is distinguished by most of its species growing in the ground or on cliffs and other rock piles, and having brightly colored inflorescences and flowers. I can find pictures of other Pitcairnia species similar to this.
It was worth the leaf-slippery, arduous climb up the cliff just to see this amazing bromeliad at this most gorgeous stage of its life cycle!
A TROPICAL JACK-IN-THE-PULPIT
There along the high backbone of the Eastern Sierra Madres one of the main features of the vegetation is the thing I've often mentioned here -- that many species are "relict," their ancestors having found refuge on those cool mountaintops when, at the end of the last Ice Age, the glaciers far to the north withdrew, taking their cooler climate with them. I've told you how magnolias, Sweetgums, hickories and many other species at our higher elevations give the forests a decidedly Appalachian feeling -- until you notice the orchids and bromeliads also present.
Still, on that steep slope above San Juan I was surprised when one of the volunteers discovered something close to North America's Jack-in-the-pulpit. It was ARISAEMA MACROSPATHUM, shown at http://www.backyardnature.net/n/07/070428jp.jpg.
In that picture you can see that this plant's pencil- like "Jack" (the flower-bearing spadix) inside the enclosing, cylindrical "pulpit" (the spathe) is much longer than the spadix of the North's Jack-in-the-pulpit. In fact, this species is much more closely related to the lesser-known "Green Dragon," Arisaema dracontium, than the regular Jack.
Our tropical Jack was still unfurling its leaves. I've seen many Jack-in-the-pulpits at this stage up north, but only when it was still cool to cold during early Spring. On our slope we were all sweating like the dickens, so it felt a little surreal seeing this species so at home here in the tropics.
A MOUNTAIN SPINY LIZARD
During car trips between destinations I rode with Roy, the Peace Corps coordinator for this part of the world. Not only did Roy entertain us with stories from a life spent in Africa, Latin America and the South Pacific, but also he was a herper -- an enthusiast of reptiles and amphibians. Wherever we went Roy was always turning over rocks and on roads he always stopped to examine scaly roadkill.
Therefore, on our first night out when I was putting up my tent and noticed a bluish lizard with a striking black collar around its neck, I called for Roy. As I tilted up the piece of plywood the lizard had hidden beneath, Roy jumped for the critter, missed him a few times, but then caught him with his hands, being sure not to grab the tail because he didn't want that to come off in his hands. Immediately Roy identified his catch as SCELOPORUS JARROVI, sometimes called the Mountain Spiny Lizard. You can see it in Roy's hands at http://www.backyardnature.net/n/07/070428ly.jpg.
Seven species of Sceloporus are officially listed for the Reserve. I've already introduced you to Sceloporus grammicus (Mesquite Lizard), which is abundant on exposed rocks everywhere. That species is pretty bland looking, but this one with its black collar with a white fringe, and a bluish body really has pizzazz.
Of course we released the critter. No collecting is permitted inside the reserve without a hard-to-get permit. And we wouldn't have wanted to remove the animal from his ecosystem, anyway.
A HUNDRED SPECKLED BUTTERFLIES ON A ROCK
One of the most spectacular encounters of the whole trip wasn't a planned one. On the road up to San Juan we stopped in a mixed juniper/oak forest to admire big cycads and look for snakes. One of the volunteers found the real stars of the stop, however, down in a shaded, protected, arroyo bed. At least a hundred butterflies with black wings heavily speckled with white spots clustered close together beneath a slightly overhanging rock. You can see a volunteer photographing the quiescent flutter at http://www.backyardnature.net/n/07/070428bu.jpg.
There's a close-up of two individual butterflies at http://www.backyardnature.net/n/07/070428bv.jpg.
Not having a field guide, I have no idea what name these butterflies go by. I'm guessing they're in or near the Ageroniini tribe of the subfamily Biblidinae of the huge family Nymphalidae. If someone can help me narrow it down more than that I'd appreciate it. They were found at about 4500 feet in elevation (1360 m) in far eastern Querétaro state, on the western slope of the Eastern Sierra Madres.
Of course, when a bunch of butterflies brings as much pleasure to a group as these did us, the name is hardly relevant. Still, I'd like to know whether the species is rare, thus constituting another reason to preserve the reserve's ecosystems.
Right before the Peace Corps volunteers arrived I'd been discussing the phenomenon of "altruism in Nature" with my naturalist friend Denise in Australia. Therefore, this week has been a good one in which to firm up my thoughts on the matter of altruism.
In biological terms, altruism is behavior of an individual whose action reduces the number of offspring it itself is likely to produce, but enhances the likelihood that one or more other organisms will be able to reproduce.
For example, when a sparrow issues an alarm call to warn others of an approaching hawk it draws attention to itself thus reducing its own potential for producing offspring, while increasing that of others. Someone jumping into a swimming pool to save a drowning stranger does the same thing.
Since altruism reduces an individual¹s reproductive potential, we should expect the workings of Darwin's natural selection to select against the altruistic trait and eventually reduce its presence within a population to zero. Even if a population were composed only of altruists, it would be vulnerable to subversion from within because a single, mutant selfish individual could exploit the altruistic tendencies of his neighbors.
Therefore, it's hard to explain how altruism evolved. In fact, more than in the past, nowadays the subject of "altruism" enters into some of the most vigorous theoretical debates about the mechanics of evolution. You might enjoy looking over a page on the subject, provided by Stanford University, at http://plato.stanford.edu/entries/altruism-biological/.
I have my own opinion about where altruism comes from. I'm not sure, but here's my best hypothesis:
The thing that is "me" is not the organism from which the altruistic urge arises. Nor is "humanity" the organism, and maybe not even "the Earthly biosphere," or "Gaia." My own humble opinion is that altruism blossoms from the body of the Infinite One, the Universal Creative Force, the pantheistic Nature that is both God and all things, and sometimes organisms find the need to harmonize with that blossoming.
When the sparrow calls to his mates that a hawk approaches, when Jarrod and Jennifer join the Peace Corps, when an individual, for the sake of the environment, decides to walk to the local store instead of driving to the mall on the edge of town, it is a firing of a synapse of the nervous system of the evolving, maturing Altruistic Everything.
To be a sentient being evolved and matured enough to be able to reflect on all this, and to consciously choose to harmonize my own behavior with the sweet, fragrant, rainbow ribbons of altruistic urges emanating from the soul of the Universal Creative Force and flowing majestically through all of time and space -- how pretty, how pretty...
Best wishes to all Newsletter subscribers,
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