Red Fox - Photo by Lee Kaiser
Almost
50 species of mammal are known to live in Arches.
Some, like desert cottontails, kangaroo rats and mule
deer, are common and may be seen by a majority of visitors.
However, many desert animals are inactive during daylight
hours or are wary of humans, so sightings can be truly
special events. Tracks and scat are the most common
signs of an animal’s presence.
Arches’ hot
climate and lack of water favors small mammals. Because
of their size, these animals are less able to migrate,
but have an easier time finding shelter and require
less food and water to live. Rodents are numerous:
there are eleven species of mice and rats alone.
One animal uniquely adapted to life in the desert
is the kangaroo rat. This rat lives its entire life
consuming nothing but plant matter. Its body produces
water by metabolizing the food it eats. However, even
the kangaroo rat is prone to spending the hottest daylight
hours sleeping in a cool underground burrow and may
even plug the opening with dirt or debris for insulation.
Larger
mammals, like mule deer and mountain lions, must
cover more territory in order to find food and water,
and sometimes migrate to nearby mountains during
summer. In Utah, around 80% of a mountain lion’s
diet consists of mule deer, so these animals are never
far apart. However, unlike mule deer, mountain lion
sightings are very rare.
Desert bighorn sheep live year-round in Arches, and
are frequently sighted along Highway 191 south of the
visitor center. These animals roam the talus slopes
and side canyons near the Colorado River, foraging
on plants and negotiating the steep, rocky terrain
with the greatest of ease. Once in danger of becoming
extinct, the desert bighorn are now making a tentative
comeback that has been fueled by the healthy herds
in nearby Canyonlands National Park.
DESERT BIGHORN SHEEP
Desert
bighorn sheep are some of the most intriguing
mammals
of canyon country. They are wary of human
contact, and blend so well into the terrain
they inhabit, that sightings are a special
event. Once feared of becoming extinct, the
desert bighorn are making a tentative comeback
in southeast Utah due to a comprehensive
reintroduction effort by the National Park
Service.
Desert or Nelson’s bighorn sheep (ovis
canadensis nelsoni) are considered by most
biologists to be a unique subspecies. Desert
bighorns have adapted to hot, dry climates,
unlike their Rocky Mountain cousins, and have
longer legs, lighter coats and smaller bodies.
Bighorn sheep are common in ancestral Puebloan
and Fremont pictographs, an indication of their
presence and prominence in indigenous cultures.
Explorers in the late 1600s estimated that
more than two million desert bighorn once roamed
the southwest.
By the late 1800s however, bighorn sheep had
disappeared or declined in many areas. Extremely
vulnerable to diseases from livestock, herd
after herd of wild sheep were decimated by
pathogens like scabies (an ear mite) and anthrax
(a bacterial disease) introduced by domestic
sheep. Bighorns were also killed by early explorers,
settlers and trophy hunters. Increased competition
with domesticated cattle and sheep for food
didn’t help the situation. In 1975, Utah’s
population numbered around 1,000 sheep.
In the early 1980s, biologists began relocating
bighorns from a native population in Canyonlands
National Park in order to establish new herds.
Since sheep are poor dispersers, this is the
only way to return them to their historic ranges.
To accomplish this, sheep are captured in nets
fired from helicopters, their health and age
assessed, and suitable animals are transported
by ground to a relocation area.
Since the program began, sheep have been reestablished
in Arches National Park, Capitol Reef National
Park and Glen Canyon National Recreation Area.
Sheep relocated to the San Rafael Swell west
of Arches have created two herds totaling more
than 600 animals. Today, the bighorn population
in Utah is estimated at 3,000 animals. There
are roughly 75 sheep in Arches, and animals
are often sighted along Highway 191 south of
the visitor center.
Human activity and development continue to
threaten the desert bighorn sheep. The mortality
rate of first-year lambs at Arches has been
alarming in recent years. Though no specific
cause has been identified, this trend may be
due to increased vehicle traffic along highways
coming into Moab. For the remaining herds to
survive, intensive management and conservation
measures may be necessary. The protection of
undeveloped land and wilderness areas is critical
to the species’ survival, and Arches
will continue to play a large role in this
effort. |
MULE DEER
Though
the natural quiet of Arches
often creates the impression
of lifelessness, many animals
live here. Birds, lizards
and some rodents are seen
most frequently, though
seasons and weather play
a large role in determining
what animals are active.
Desert animals have
a variety of adaptations
for dealing with the
temperature and moisture
stresses present in Arches.
Most desert animals are
nocturnal, being most
active at night. This
can be an adaptation
to both predation and
hot summer daytime temperatures.
Mostly nocturnal animals
include kangaroo rats,
woodrats (also called
packrats), and most other
small desert rodents,
skunks, ringtails, foxes,
bobcats, mountain lions,
bats and owls.
Animals
that are most active
at dawn and dusk are
called “crepuscular.” These
times of day are cooler
than mid-day. The half-dark
makes prey animals less
visible, yet visibility
is good enough to locate
food. Some animals are
crepuscular mostly because
their prey is crepuscular.
Crepuscular animals include
mule deer, coyotes, porcupines,
desert cottontails, black-tailed
jackrabbits, and many songbirds.
A
few desert animals are
primarily active during
the day, or “diurnal.” These
include rock squirrels,
antelope squirrels, chipmunks,
lizards, snakes, hawks,
and eagles. Many animals
have a temperature range
in which they are active,
so alter their active times
of day depending on the
season. Snakes and lizards
go into an inactive state
of torpor during the winter,
are active during the day
during the late spring
and early fall, and become
crepuscular during the
heat of summer. Many insects
alter their times of activity.
Mosquitoes, for example,
may be out at night, at
dawn, dusk or all day but
not at night, depending
on the temperatures. |
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PEREGRINE
FALCON
The Peregrine
Falcon has the most extensive
distribution of any  bird
in the world. The American
peregrine falcon is found
in Arches, typically nesting
in shallow caves high on
cliff walls along the Colorado
River. Their diet consists
almost exclusively of birds,
and the sound created as
they attack their prey can
be startling. In a dive,
peregrines may attain speeds
exceeding 200 miles an hour,
making them without a doubt
the fastest bird.
From 1940 through the early
1970s, the use of DDT as
a pesticide caused a precipitous
decline in the peregrine
population. This chemical
agent caused eggshell thinning
and breakage, and in some
areas successful reproduction
stopped altogether. The peregrine
was listed as a federally
endangered species in 1973.
Restrictions on DDT pesticides
and coordinated recovery
efforts have led to a remarkable
comeback. From a low of about
324 nesting pairs in the
U.S. and Canada in 1975,
roughly 1,650 nesting pairs
were counted in 1999. In
1999, the American peregrine
falcon was removed from the
endangered species list,
though the species is not
fully recovered throughout
its range; rather, it is “no
longer threatened with extinction
in the foreseeable future.” Peregrines
are still on the state endangered
species list in Utah, but
the species is fairly common
in the canyons of southeast
Utah.
In 1989, the National Park
Service began a three-year
program to determine peregrine
populations in western parks.
Arches continues to monitor
peregrines today, and one
pair is known to nest in
the park.
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Along with cacti and sand
dunes, reptiles have become icons of the
desert. The only reptiles found in Arches
are snakes and lizards, underappreciated,
sometimes feared, animals that play an important
role in the high desert ecosystem. Lizards
and snakes help control insect and rodent
populations. In turn, both are potential
meals for birds and mammals.
All
reptiles are cold-blooded or, more accurately, “ectothermic,” regulating
body temperature via external sources rather
than internal metabolism. A reptile’s
metabolic rate is very low, but so are
its energy needs. Since keeping warm in
the desert does not require much work,
reptiles are well adapted to this environment.
What energy they do generate can be used
for reproduction and finding food instead
of heating and cooling.
Of
course, there are drawbacks to this lifestyle.
Since they don’t pant or sweat, reptiles
can’t endure extremely high temperatures
without shade. Nor can they endure prolonged
sub-zero temperatures. When it’s cold,
reptiles hibernate or enter into an inactive
torpor. Food stored as fat in their tails
helps lizards survive these long periods
of inactivity, so losing a tail can be life
threatening.
If you visit Arches during the summer, you
are sure to see lots of lizards. After birds,
these reptiles are the most active animals
once daytime temperatures reach 90 degrees
and higher. They are usually visible sunbathing
on rocks or chasing insects with their lightning-quick
reflexes. Lizards found here include the
northern whiptail, the desert spiny, and
the colorful western collared lizard.
Most of the snakes found in Arches are harmless
and nocturnal. All will escape from human
confrontations given the opportunity. The
midget-faded rattlesnake, a small subspecies
of the western rattlesnake, has extremely
toxic venom. However, full venom injections
occur in only one third of all bites. The
midget-faded rattlesnake lives in burrows
and rock crevices and is mostly active at
night. |
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Amphibians may
be the last thing people think
of when they visit Arches. However,
the park is home to a variety of
frogs and toads, as well as one
species of salamander. Witnessing
a chorus of toads may be one of
the most memorable experiences
canyon country has to offer. It
is an awesome event that can fill
a canyon with sound, sometimes
for hours.
Amphibians are animals that
have two life stages: a larval,
aquatic form and an adult, terrestrial
form. This is the difference
between a tadpole and a frog.
In Arches, amphibians lay their
eggs in the potholes, springs
and intermittent streams like
Courthouse Wash.
Adult amphibians may wander away
from water, but usually remain
nearby and wait out dry periods
in burrows. Breeding (and toad
choruses) usually occurs on spring
and summer nights after significant
rainfall. Male frogs and toads
do the vocalizing. Females lay
long strings of gelatin-covered
eggs which, depending on the species,
may hatch within hours. Metamorphosis
can take weeks, though the Great
Basin spadefoot toad transforms
to adulthood in as little as 14
days, the quickest of any amphibian. |
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WARNING:
Feeding wildlife can be very detrimental
to their health. It can destroy their
natural ability to find food and
create a dependency on humans. Animals
that develop such a dependency often
become aggressive toward humans and
must be relocated or even killed. |
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