The Cactus Wren-dition, Spring
2002, newsletter of the Maricopa Audubon Society, Phoenix, Arizona
An educational tool about cattle grazing
In the relations of man with the animals, with the flowers, with the
objects of creation, there is a great ethic scarcely perceived as yet, which
will at length break forth into light. —Victor Hugo
by Bob Witzeman
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
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. 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
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.
On the left side of the two dioramas is a water seep,
spring or wetland that would normally have lush grass, or cattails and
bulrushes. These wetland plants are also “ice cream” plants to cattle.
With the arrival of cattle in the 1870’s such vegetation at these
springs and wetland seeps was rapidly and systematically obliterated.
Ranchers erected small dams, stock tank impoundments, or windmills at
these areas. Such areas are now deathtraps for wildlife that approach these
defoliated, cattle-blasted moonscapes. Without the protective cover of
vegetation, wildlife fear approaching, and if they do they become easy prey from
predators, or from diseases from cattle-polluted water. Birds, mammals,
amphibians, and other reptiles, dependent on these vital watering spots in the
desert, have suffered greatly.
Many destructive species of exotic grasses introduced by
the government for the cattle industry have replaced our native grasses and
vegetation. Some introduced grasses
burn hotter than the native grasses. The
intense heat from these fires can kill our unique saguaro forests. Other
introduced grasses have shallow root systems, frustrating groundwater recharge
and increasing storm run-off. This
results in more soil erosion and frequent washouts of the cottonwood/willow
galleries during desert cloudbursts and monsoon storms.
Audubon members should make a game or puzzle out of trying
to find out why and how cattle grazing harms (or helps) each of the various
species listed in the graphic. The Maricopa Audubon Society will hold workshops
on grazing- watch our Cactus-Wren-dition newsletter for dates.
MAS will make poster enlargements of these compelling dioramas of Karen
Klitz so we Audubon volunteers can explain it to Arizonans at public display
The Maricopa Audubon Society, besides extending its deep appreciation and thanks to Karen Klitz, also wishes to thank Dr. Martin Taylor of the Center For Biodiversity, and Dr. Robert Ohmart of Arizona State University, for their assistance and guidance in this project.