Naturalist Newsletter of October 29, 2007
issued from Yerba Buena Clinic just outside
Pueblo Nuevo Solistahuacan, Chiapas, MÉXICO
about 1740 meters in elevation, ± LAT. 17° 11' 27"N, LONG. -92° 53' 35"W
The first half of this week it rained day and night. Sometimes it was torrential but mostly it was the kind of billowy fog-drizzle you'd expect on the coast of England, not upland southern Mexico. On the Gulf slope avalanches blocked roads while here trees toppled and electricity came and went. During one long blackout I took a walk in fog-rain to see what the birds were up to.
Big trees with trunks and branches heavily festooned with bromeliads, ferns and orchids formed colorless silhouettes in the fog. Sounds were muted and all one heard was rain splattering on the ground and leaves. Every pine needle and ever blade of grass, the tip of every ray-flower on every composite blossom bore a silvery droplet, and after a while so did every hair in my beard and eyebrows, and atop my hands.
Eventually the somberness was broken by a small flock of robins behaving like kids in a playground as they ranged through treetop after treetop, an occasional pair making a lusty chase that ended in nothing. Their nasal kweh-kweh-kwehs cut through the fog, sounding just like any playful little band of backyard American Robins in the north.
Though they sounded almost exactly like American Robins and their silhouettes in the fog looked like American Robins, they weren't. They were Rufous-collared Robins, sometimes called Rufous-collared Thrushes, TURDUS RUFITORQUES, a species endemic just to the highlands of Chiapas, Guatemala and rarely spotted in neighboring El Salvador and Honduras. Often as I'm typing, a few feet outside my window, Rufous-collared Robins hop in the grass with their high-raised heads turning this way and that, looking for prey down in the grass. In so many ways Rufous-collared Robins are exactly like American Robins, except for conspicuous rufous collars, which basically are the American Robin's "red breast" extended onto and around the neck, as seen at http://www.xelapages.com/gbrc/Rufouscollarthrush.gif.
American Robins, Turdus migratorius, don't live this far south. They're one of those north-centered species whose distribution follows Mexico's highlands southward only as far as the lowland Isthmus of Tehuantepec.
In the title I mention our local robin "theme." I'm referring to my oft-repeated notion that the Creator is an artist, and living things constitute Her art. In bird terms, robins -- by which I mean the genus Turdus -- constitute a theme the same way a melody might in a Bach fugue. As Bach gave us many delicious variations on his fugues' themes, the Creator has given us variations on themes of Her species.
Just in Mexico we have eight variations on the robin theme -- eight species of the genus Turdus. There's an all-black one, like Europe's Blackbird, endemic to southern Mexican cloudforests. There's a "Clay-colored" one found all through the Gulf lowlands, and a "White-throated" one with black stripes on the white throat, and one, Turdus graysoni, that in the whole world is found only around San Blas in the state of Nayarit on the Pacific coast, and the Tes Marías Islands just offshore. Some species have yellow eye-rings but most don't, some have yellow legs while ohers have flesh- colored ones or dark ones. None of the others have our Rufous-collared's rufous collar, though.
The most widespread of all our Turduses is the American Robin, so that's Mexico's main robin melody. The Rufous-collared Robin outside my window right now is a lovely Chiapan/Guatemalan highland variation on that Turdus theme, maybe one with a marimba, pine-scented beat.