El Pinacate y Gran Desierto de Altar Biosphere Reserve, January 23-24, 2016
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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