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Thanks to the outstanding talents of artist Karen Klitz of
Berkeley, California, conservationists here in the Southwest
now have an exciting new educational tool.
The graphics accompanying this article depict some of
the before and after impacts of cattle grazing in the arid
Southwest. In the U.S., cattle grazing is the largest single
factor in species imperilment.
Here in Arizona our state Game and Fish Department
biologists have determined that livestock grazing has been a
factor in some 70 of the 116 species of state-listed animals
threatened or already extirpated from Arizona. This includes
23 of the 29 birds threatened in this state, 21 out of 25 of
our threatened native fish, 9 of our 20 listed herpetiformes
(e.g. reptiles, amphibians), 14 of our 21 threatened mammals,
and four of our 21 listed invertebrates.
These state-listed threatened species are not necessarily
threatened in the U.S. or in their ranges in the world, but
they are threatened as breeding members of our state’s
fauna. Two bird species have cattle grazing as a factor in
their extirpation in Arizona, namely, Aplomado Falcon and
Masked Bobwhite. Shooting, poisoning or trapping by the cattle
industry has been responsible for the extirpation of at least
five of Arizona’s mammals:
Mexican wolf, grizzly bear, black-tailed prairie dog,
black-footed ferret, and jaguar.
Twenty-three of our 29 threatened bird species have impacts
from cattle grazing while only 3 on that list have threats
from logging.
There are some 265 million acres of BLM and USFS lands.
Eighty percent of these are grazed. These lands belong to ALL
of the citizens of the U.S.
The U.S. Supreme Court has determined that grazing on
these lands is not a right but a privilege.
These lands produce only some 2% of the nation’s
forage for cattle. Public lands grazing costs the federal
government a net loss of half a billion dollars annually in
subsidies and damage costs exceed grazing receipts from
ranchers. BLM, USFS and State Lands together make up 55% of
Arizona. Eighty
percent of these lands are grazed.
When one adds grazed Indian lands in Arizona, much more
than half of Arizona has systematically undergone
desertification and destruction from livestock grazing over
the last 130 years.
The impact of removing cattle from OUR public lands would
have an invisible impact upon U.S. beef production. But it would have a highly visible impact upon our streams,
soils and landscape vegetation.
In the accompanying “before” and “after” cattle
grazing illustrations, note how the water table has dropped
after livestock introduction.
The illustration shows how the roots of the cottonwood,
willows, and mesquite and other riparian vegetation are no
longer able to reach the water table.
Grazing with its destruction of native grasses and
forbs causes rapid run-off following rainstorms.
Rapid run-off prevents sufficient time for the water to
percolate into the water table. In addition, groundwater
pumping such as for livestock windmills and water catchments,
and for irrigated fields for alfalfa and other cattle forage,
are key factors in lowering water tables.
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Groundwater extraction adjacent to our desert watercourses
causes reduction of in-stream flows, as well as lowering the
water table and impacting riparian root zones (see
illustrations). As
a result, Arizona’s once lush desert watercourses like the
San Pedro, Verde, Salt, Gila, Bill Williams and Big Sandy
Rivers have lost much of their native fish, wildlife and
esthetic values. As the graphics show, these riparian areas
are needed by the majority of Arizona’s birds, mammals and
other wildlife at some point in their life cycles.
Arizona once had many beautiful grassland habitats.
They have now undergone desertification and become
desert-scrub at best, and often simply moonscapes.
Grassland species such as Grasshopper, Baird’s,
Botteri’s, and Cassin’s Sparrows, Montezuma Quail,
Sprague’s Pipit, and longspurs, are just a few avifauna that
have suffered from the desertification and conversion of the
Southwest’s grasslands to desert wasteland.
The “after cattle” illustration shows mesquite and
prickly pear replacing grassland.
Cattle feces carry mesquite seeds.
These stunted mesquite are unable to support wildlife
in the productive manner of riparian mesquite bosques.
Riparian bosques, even though often some distance from
the actual streams, can survive so long as their taproots can
still reach the water table. They support an immense variety of wildlife and
cavity-nesting species.
Few realize that cattle preferentially eat willow and
cottonwood seedlings and saplings as if they were ice cream. They are able to straddle and push over between their front
legs a 12-foot cottonwood or willow and by defoliation kill
the sapling.
One important role of the Southwest’s riparian trees such
as willow, cottonwood, sycamore, ash, alder and mesquite is
that these trees create a canopy over the river which reduces
sunlight and reduces stream temperatures. The humidity
envelope of the overhead canopy creates a prolific bird and
insect ecosystem. The reduced water temperatures also are
essential to healthy native fish populations.
Also since insects are more plentiful and fall from the
overhanging trees, this means more prey for wildlife.
Cattle feces and urine causes eutrophication or algal bloom
in rivers. Since
the cows have eaten the trees that would have shaded the water
and kept it cool, the resulting increased stream temperatures
and nitrogen-loading intensify eutrophication. The subsequent
low oxygen levels and fish kills are not the only problem.
Increased stream sedimentation from soil erosion due to
overgrazing in uplands as well as cattle hoof destruction of
streambanks increases water turbidity.
Besides directly killing many fish species, this
impedes the ability of the endangered desert-nesting Bald
Eagles to see and capture fish prey. This also means less prey
for other fish-eating birds and mammals.
Equally serious, eagles have better reproductive survival if
they nest in riparian trees rather than on cliffs. Not only are the nests along Arizona’ s desert cliffs
overheated, they have more nest parasites which attack the
eaglets.
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