Cabeza PrietaBalance in the Desert |
Balance in the Desert at Cabeza Prieta National Wildlife Refuge (NWR) in Arizona. Published by the U.S. Fish & Wildlife Service (USFWS).
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U.S. Fish & Wildlife Service
Balance in the Desert
Cabeza Prieta
National Wildlife Refuge
Balance in the Sonoran Desert
The Sonoran Desert Ecosystem is a complex
orchestra of plants, animals, geology and
climate. All members of this community
depend on each other for a harmonious and
balanced existence.
Here, wildlife has adapted to, and depends
on, daily heat and seasonal rain cycles. The
dramatic landscape is the result of the arid
climate and the geological history.
This field guide is an introduction to the
Sonoran Desert Ecosystem. We hope it will
help you fall in love with this beautiful area
and learn to respect its delicate balance.
the saguaro. Each spring, while drinking the
nectar from the blossoms, the bat pollinates
the flowers with pollen collected from
previous visited saguaros. During the
summer, the bats eat the saguaro’s fruit and
distribute its seed in their guano.
The Gila woodpecker carves pockets in the
thick flesh of the saguaro to use as safe
nesting places. The saguaro lines these
wounds with scab-like crusts, called boots.
When the woodpeckers abandon their
cavities, elf owls will nest and seek refuge
there.
The six plants discussed in this guide can be
found throughout the Sonoran Desert and in
the garden area in front of the Visitor
Center at the Cabeza Prieta National
Wildlife Refuge.
A young saguaro depends on shrubs and
trees for shelter. These nurse plants protect
the saguaro seeds, and young plants from
intense desert floor heat and trampling.
Most mature saguaros have outlived their
nurse plants. Saguaros may live to be 200
years old.
Caution: Please watch your step! Venomous
snakes and lizards in the area.
Foothill Palo Verde: Leaf or
Leafless?
Creosote is Everywhere!
The creosote bush is one of the most prolific
plants of North American deserts. Many
animals depend on this bush for food and
shelter. The creosote grasshopper lives and
feeds exclusively on this plant. It eats the
small resinous leaves that creosote has
developed to conserve water. The
threatened* California leaf-nosed bat will
descend upon a creosote in search of large
night flying insects.
The creosote bush is an ideal place for small
burrowing animals to excavate their homes.
The branches hide burrow entrances of
desert pocket mice and western whip-tail
lizards from their predators, bobcats and
American kestrels. The creosote’s broad and
shallow root system is well adapted to the
desert’s infrequent and light rains. The roots
also support the soil around the animals
burrows, which increase the water and air
supply to the creosote’s roots. Any material
that accumulates in the burrow, such as scat
or grass used for nests, will eventually
decompose and enrich the soil.
Saguaro: A Desert Giant
The saguaro is the most conspicuous cactus
of the Upper Sonoran Desert and bears the
state flower of Arizona. The lesser longnosed bat, an endangered species, has
developed a codependent relationship with
The foothill palo verde, from a distance, may
appear to have been stripped of its leaves
and dipped in paint. Actually, the tiny leaves
and photosynthetic bark are the tree’s
adaptations to conserve water. Under a palo
verde is a good place to find a black-tailed
jack rabbit feeding on the tree’s leaves and
seed pods. While the jack rabbit eats or
rests, it hides amongst the tree’s branches
from its sly and quick predator, the coyote.
Look for jack rabbit signs, their pellets are
larger than the desert cottontail’s. A moist
greenish pellet is a sign that the animal has
been here recently.
Once the seed pods are opened by the jack
rabbit, Merriam’s kangaroo rat will collect
the seeds that the rabbit missed, eat some,
and store the rest in caches up to 200 feet
away. Later, the rat returns for the
remainder of its collection - if it can find it.
Often, all of the seeds are not recovered; a
few of the ones left behind may germinate
and grow into new trees.
Bursage: A Stabilizing Savior
When it rains, water runs down the
mountain slopes and carries with it loose rock
material. As the speed and force of the water
decreases toward the base of the mountain,
rocks, gravel and sand are deposited in
graceful sweeping fan shapes at the mouths
of the canyons. These formations are called
alluvial fans. Over time the fans grow, merge
together and fill the valley floor, creating the
ever-changing and shifting, wash-creased
bajadas. Bursage grows on the bajadas, and
is one of the most important soil stabilizers in
the Sonoran Desert. Its roots help to keep
the loose soils from washing away during
rain. Bursage is often one of the first plants
to take root in a disturbed area. It is also an
important browse plant for the desert
cottontail and the endangered Sonoran
pronghorn.
A Thorny Fortress of Chainfruit
Cholla
The chainfruit cholla is one of many chollas
found in the Sonoran Desert. The cactus
wren builds its nest between the chainfruit’s
branches. Even the bush climbing Sonoran
whipsnake avoids the thicket of spines
guarding the nest and hatchlings.
Although the cholla’s spines make the plant
difficult to eat, the Harris antelope squirrel
feeds easily on its fruit. Like other chollas,
the chainfruit has jointed stems that detach
easily and take root when they fall to the
ground. Some of these joints are collected by
white-throated wood rats, which eat the
juicy flesh and use the spines to build
fortresses around their homes. The spines
help to ward off predators.
Desert Ironweed: A Hardy Host
The desert ironweed provides many plants
and animals with food, shelter and nesting
places. Phainopeplas nest in the ironweed
and eat the juicy berries of the desert
mistletoe, which grows on the tree’s
branches. When these birds fly from tree to
tree, they distribute the sticky mistletoe
seeds in their droppings. In winter, mule
deer also feed on mistletoe. The dry and
relatively ice-free climate in the Sonoran
Desert makes decomposition a slow process.
Generations of termites and desert
millipedes will gnaw, sometimes for hundreds
of years, at a majestic deadwood snag,
making the nutrients of the dead tree
available for the organisms in the ecosystem.
Now that you have had a brief glimpse at
this ecosystem, we hope you will soon find a
chance to sit, watch, and listen to the
wildlife, plants, landscape, and climate of
remote areas of the Sonoran Desert. If you
have any questions or comments, please
come see us in the Visitor Center.
Written by Magdalen A. Wilson