Sonoran
Pronghorn Antelope Pronghorn
Antelopes are native to America and are found
nowhere else in the world. They are the last
surviving member of the Antilocarpidae family. Once
they were as abundant as the buffalo. But by the
1920s only about 13,000 animals remained. Due to
conservation and range management there are now
about 500,000 pronghorns in the United States and
Canada. The Mexican population isn't doing as well
and it is estimated that only 1,200 animals
remain. Part of
this dwindling population consists of the Sonoran
Pronghorn Antelope, a desert sub--species of the
pronghorn. Only about 480 animals remain in North
America and they are on the brink of extinction.
They are found only in two small areas of the
Sonoran Desert of southwestern Arizona and northern
Mexico. In Arizona they are found in
alluvial valleys,
separated by mountains and mesas. It rains in the
winter and summer, but spring and autumn bring very
dry, arid weather. The landscape is dry and
sparsely vegetated with cactus, creosote bush,
tumbleweed, and ocotillo. Smaller
than a white-tailed deer, the Sonoran pronghorns
stand less than 3 feet at the shoulders. Their
overall body length, including their short tail, is
48 to 57 inches. Males can weigh 90 to 130 lbs. and
females 75 to 110 lbs. Females are about 10%
smaller than the males. The upper part of the
Sonoran pronghorn is a rich tan color. Their
underpart, rump , and two bands across their neck
are white. A short 2-4 inch black mane runs down
the back of their neck. Males have a black mask and
black cheek patches. Their eyes
are set high on their heads, and are very large in
comparison to their body. They can see something
moving as far as 4 miles away. The pronghorn has a
unique ability to raise patches of its stiff,
hollow hair to release body heat in the hot summer.
In the winter months the hairs insulate them
against the cold. The pronghorn also has very
special horns. Both males and females have antlers.
The female antlers are short. The male has large,
straight pronged antlers about 12 inches long which
curve back at the ends. They are made of an outer
sheath of black keratin which grows around a
permanent bony core. After the breeding season they
lose the sheath, but the short horn underneath
remains. Next year new antlers grow back over the
bony horn. Sonoran
pronghorns are lightly built and have long, slender
legs which allow them to run faster than any mammal
in North America. They can reach speeds of 60 miles
per hour for short bursts, but can run at 35 miles
per hour for long distances. Both their speed and
keen eyesight help them avoid predators. They are
able to make the white hairs on their rump stand
straight up to signal danger. This white flag can
be seen from a long distance. Their one weakness is
their curiosity. They will often return to see what
scared them in the first place. Native Americans
and early settlers used this weakness to lure them
into a trap by waving a piece of cloth or
branch. Pronghorn
does can breed at 16 months, and bucks are ready
when they are 1 year old. The Sonoran pronghorn
breeds from July to September. Their gestation
period is about 245 days. The doe gives birth to 1
and sometimes 2 fawns which weigh about 5 to 7 lbs.
She will hide her fawns in separate places in dips
or swales, and come back to feed them twice a day.
The fawns have no smell, and lie very still, which
makes it difficult for predators to find them. They
are weaned at 4 to 5 months and reach their mature
size at 6 months. Pronghorns
are ruminants. They have a four part stomach which
lets them digest rough textured food and get more
moisture from it. The Sonoran
pronghorns are listed on the U.S. Endangered
Species Act, and endangered by the IUNC, or
International Union for the Conservation of Nature.
It is also listed as CITES Appendix I. The
Convention on International Trade in Endangered
Species is a United Nations treaty which regulates
international trade in wild animals and plants.
Poaching, habitat loss from overgrazing of cattle,
and restriction of movement by fencing (pronghorns
don't jump) are all threats to its survival. Fawns
are vulnerable to coyotes, bobcats, and golden
eagles. 2002
bibliography: Photo courtesy of the US Air Force "The Pronghorn Antelope", http://www.ngpc.state.ne.us/wildlife/antelope.html, (9/8/02). "The Pronghorn &endash; Antilocapra americana (Desert USA)", http://www.desertusa.com/mag99/may/papr/pronghorn.html, (9/8/02). Ingmarsson, Lisa. "Antilocapra americana sonoriensis (Sonoran Pronghorn): Narrative", http://animaldiversity.ummz.edu/accounts/antilocapra/a._americana_ sonoriensis$narrtive.html , (9/8/02). "Species Profile for Sonoran pronghorn", http://eos.fws.gov/servlet/SpeciesProfile?spode=A009 , (9/8/02). "Rolling Hills Refuge &endash; Wildlife Conservation Center", http://www.rhrwildlife.com/theanimals/p/pronghorn/ , (9/8/02). "Defenders of Wildlife &endash; Habitat & Highways Campaign", http://www.defenders.org/habitat/highways/new/target/pronghorn. html , (9/8/02). "Sonoran Pronghorn Antelope", http://www.co.pima.az.us/cmo/sdcp2/fsheets/sp.html , (9/8/02). |