El Pinacate y Gran Desierto de Altar Biosphere Reserve, January 23-24, 2016 => click on the thumbnail image to see the original larger image <=
El Pinacate y Gran Desierto de Altar Biosphere Reserve in Sonora, Mexico, below Arizona, is comprised of a volcanic group of peaks and cinder cones (the Pinacates) and a vast sand dune field, the largest in the Americas. I rode in the back seat behind Paul Dayton and Ed Parnell, to an ecological study site in a volcanic desert area, with the Pinacate Peaks in the background. They drove on an obscure, long track to the isolated study site... I would not call it a road.
El Elegante, a collapsed volcanic caldera	a'a lava flow, with cinder cone in distance	view from a'a lava flow, with more cinder cones
Hohokam pottery shards, c1000	Ed Parnell downloading rainfall data Pinacate Peaks in background	packrat midden under teddy bear cholla a nocturnal packrat leaves its midden at night, to gather cholla balls dropped on the ground; the packrat carries the cholla balls back to its midden, eats their insides, and places the cholla ball husks around its midden for defense against predators.
Paul Dayton counting buds fallen on the ground from a teddy bear cholla a surrounding chicken wire cage keeps the cholla balls from getting eaten by packrats Pinacate Peaks in background	mistletoe seeds trying to grow into a host plant birds eat the mistletoe berries, dropping the sticky seeds onto the branches on which they are perched; the mistletoe seeds then try to grow into that branch to parasitize the plant	teddy bear cholla these reproduce asexually by the fallen balls, and the fruits usually have no viable seed
young ocotillo sheltering under a teddy bear cholla the cholla acts as a nurse plant, both shading the young ocotillo from the desert sun and heat, and warding off jack rabbits and other animals that would eat the tender branches of the young ocotillo. Without the nurse plant, the young ocotillo may not survive, and it will outgrow the nurse plant with time.	an older ocotillo that has outgrown its creosote bush and cholla nurse plants you can see the cholla cactus wood laying on the ground	chain cholla
ocotillo blossom before opening	multiple young branches of an ocotillo that have been nibbled back by jack rabbits it's better to grow up and away from the nibbling jack rabbits.	saguaro cactus with owl hole up high
packrat runway from its midden to a cholla the packrat's regular visits to gather dropped cholla buds from its midden in the background to the cholla in foreground, create a furrowed runway	closer view of that packrat's midden under chain cholla	Paul Dayton counting dropped cholla buds from a caged cholla most of the caged chollas were very productive in dropping buds; uncaged chollas had far less dropped buds underneath because so many get eaten.
the jackrabbit may scratch out depressions, in which it deposits fecal pellets with time, these depressions can support plant growth, by pooling water from rainfall, with fecal pellets fertilizing the soil.	sun setting with Pinacate Peaks at left	Sonora desert scene near sunset
desert near sunset	saguaro adjacent to palo verde tree nurse plant (with a mistletoe clump)	extensive packrat midden
Hohokam Indian path, c1000	just before sunrise	upended teddy bear cholla bud, to show the roots it puts down into the desert soil
desert scene, Pinacate Peaks at left	desert scene with packrat midden in foreground	Senita cactus under palo verde tree nurse plant
desert scene	packrat midden in middle, with runway leading to left foreground Pinacate Peaks in background	closer view of packrat midden under cholla
packrat midden under Senita cactus	closer view of packrat midden under Senita cactus	red tailed hawk who would like to eat packrats
Senita cactus with palo verde tree nurse plant		desert scene