Conspicuously perching atop boulders along the trail leading from the crater on the northern slope there's a species even more exquisitely wedded to these high-elevation cold winds, low grass and rocks, for they spend their entire year here, not migrating north or south. They are endemic to the Mexican mountains from Chihuahua south to Oaxaca and my field guide says that they occur only in grassy openings, meadows and pine forests between 1500 and 4200 meters (5000-14,000 feet). Here we're a bit higher than 4200 meters. It's the Striped Sparrow.
It's always a special pleasure to meet organisms whose adaptations are so refined that their species' distribution and habitat requirements are very narrowly defined. It's like finding a geode with perfectly formed and preserved crystals inside: One senses the enormity of time needed for the step-by-step unfolding of such an exquisitely particular thing.
If one wishes to hear the landscape speaking, then surely nothing articulates more eloquently and beautifully than a lifeform evolved to exist exactly there and no place else.