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Description:The pronghorn antelope is a small ungulate, and the only member of the family, Antilocapridae. Antelopes average 4.6 feet (141 cm) long and 2.8 feet (87 cm) tall and weigh from 77-154 pounds (35-70 kg), depending on sex and life stage. Pronghorn antelopes vary in color from light tan to brown, with large white patches beneath the tail and on the underbelly. Dark brown to black hair runs down the back of its neck, creating a thick mane; and males have a black "mask" of hair on their face. Both males and females have horns, however the female horns are quite small, whereas male horns can get up to 18 inches (45 cm) long in a season. Antelopes shed their horns every year.
Life History:Female pronghorn antelopes reach sexual maturity at about 16 months; however males often do not breed until three years of age due to competition from older males. They breed once per year and mating occurs from July to October, with males aggressively defending their territory from March-October. Gestation averages 252 days, and in late May or early June, 1-2 fawns are born. Fawns are weaned in approximately 3 weeks and become independent after 1-1.5 years. The range of this species is highly dependent on food supply but can span from 2.5-5 square miles in summer and 6.5-22.5 square miles in winter. Pronghorn antelope can run at speeds of up to 60 miles per hour. The average lifespan of a is nine years and they are preyed upon by coyotes, mountain lions, bobcats, and wolves. Antelopes are herbivores, feeding on grasses, shrubs, stems and leaves. Sagebrush is the preferred browse in winter and forbs with high water content are preferred in summer.
Habitat:Pronghorn antelopes live in desert, sage scrub, and grassland habitats. Pronghorn antelopes prefer a wide variety of plants in their diet.
Distribution:Antilocapra americana
are native to North America and are found on the Great Plains and Western US from northern Mexico to southern Canada.
Status:The pronghorn antelope was historically overhunted from colonization until the mid 20th century, when the numbers dropped from 35 million to 20,000 individuals. However, because antelope are an important game species, their populations are now well-managed and the species is rebounding.
The Warm Deserts ecoregion is characterized by mountains, deserts, valleys, and desert scrubland. This ecoregion can be divided into three main subregions: Chihuahuan Desert, Sonoran Desert and Mojave Basin and Range.
Climate & Topography
The soils in this ecoregion are dry, alkaline, coarse and rocky soils. The only exception is in the Chihuahuan Desert Grasslands, which contains more fine-textured silts and clays, allowing it to support native bunchgrasses. The elevation ranges from 280 feet (85 m) below sea level in Death Valley to 10,800 feet (3300 m) in the mountains. Average precipitation ranges from 7-14 inches (17-34 cm) across most of the region, occurring from July to October. Precipitation extremes occur in the desert vallleys and mountains where precipitation amounts range from 0.2 inches (0.5 cm) to 36 inches (90 cm) a year. The average temperature ranges from 55-70 degrees F (5-24 deg C) and the growing season lasts from 150-365 days. Hydrology in this region consists of mostly intermittent and ephemeral streams, with a few large perennial streams such as the Rio Grande, Pecos and Colorado Rivers.
Vegetation & Wildlife
At the highest elevations in the mountains where there are larger amounts of precipitation, wooded areas of southwestern white pine, ponderosa pine, and whiteleaf oak forests can be found. These are often interspersed with riparian woodlands of little walnut, oak chaparral, and grapevines. The major vegetation types found in this ecoregion include the trans-Pecos shrub savanna, grama-tobosa desert grasslands, oak-juniper woodland and mesquite-tarbrush desert scrub. Topography generally dictates what type of vegetation will be found in an area. Some examples of wildlife found in this ecoregion are: mule deer, desert bighorn sheep, pronghorn antelope, bobcat, collared peccary, coyote, Montezuma quail, bronzed cowbird, black-capped vireo, western spadefoot toad, crevice spin lizard, Big Bend gecko, little striped whiptail, gray-banded kingsnake, Texas-Pecos rat snake, and the black-tailed rattlesnake.
Land Use & Environmental Impacts
Common land use practices are irrigated agriculture, grazing and mining. Human impacts on this region include overgrazing of cattle on desert grasslands. Overgrazing combined with drought has allowed invasive thorny shrubs such as honey mesquite to replace many of the native grama species. The riparian areas in this region have also been severely impacted by the invasives giant reed and saltcedar.
Invasive Species Spotlight: Giant Reed
[Photo: John M. Randall, The Nature Conservancy, Bugwood.org]
Giant Reed Arundo donax
Description:Giant Reed is an herbaceous, perennial grass of the Poaceace family that can grow over 20 feet tall. "Corn-like" stems up to 2 inches (5 cm) thick form dense masses from which penetrating roots reach deep into the soil. The leaves are bluish green and elongate, 1-2 inches (2.5-5 cm) wide and 1 foot (30 cm) long.
Life History:The seeds of giant reed are not viable, thus it reproduces vegetatively, via rhizomal sprouting. Giant reed flowers from August to September in the form of 2 foot long (60 cm) panicles.
Habitat:Giant reed tolerates a wide variety of environmental conditions including many different soil types from coarse sands to fine-textured clays and high salinity soils. Giant reed prefers well-drained moist soils and grows well in ditches, stream, and on riverbanks and in other places with a high water table.
Distribution:Arundo donax
is native to India, but was brought to California in the early 1800s. Giant reed is found throughout most of the southern US and is prevalent in the Central Southwest.
Status:Giant reed forms dense stands in riparian ecosystems, which alters stream hydrology and crowds out native plants, and alters habitat for wildlife. This species is also highly flammable and increases the fire potential in an area.
[Photo: R. Sivinski, New Mexico Rare Plants, nmrareplants.unm.edu]
Pecos Sunflower Helianthus paradoxus
Description:The Pecos sunflower is an annual forb of the Asteraceae family, which grows from 3.3-9.9 feet (1-3 m) tall. The Pecos sunflower has several solitary flowering heads, with yellow, flowering rays, which are 2.0-2.8 inches (5-7 cm) across and have purplish-brown disc flowers in the center. The leaves are green and lanceolate, 6.9 inches (17.5 cm) long, and 3.3 inches (8.5 cm) wide.
Life History:The Pecos sunflower grows in dense stands where suitable habitat is found. This species reproduces from seed and is pollinated by a variety of insects. The Pecos sunflower blooms from September through October. Seeds germinate two to three months later with some seeds exhibiting much longer dormancy periods.
Habitat:The Pecos sunflower only grows in desert wetlands (cienegas) associated with desert springs found in the Chihuahuan Desert. This species requires saturated soils for growth and tolerates the highly saline conditions found in desert wetlands. This species grows at elevations of 3300-6600 feet (1000-2000 m).
Distribution:Helianthus paradoxus
is found in five counties in eastern New Mexico and two counties in west Texas (Pecos and Reeves counties).
Status:The Pecos sunflower was listed as a federally threatened species in 1999. This species was listed due to its small range and threats from habitat modification. Factors that may affect this species' habitat are erosion, groundwater depletion, filling of wetlands and exotic saltcedar invasion. These plants are also threatened by livestock grazing and hybridization. Several of the populations of the Pecos sunflower are located on federal and state lands and other privately protected lands (i.e. Nature Conservancy lands).
![Image of Giant Reed, courtesy of John M. Randall, The Nature Conservancy, Bugwood.org]](https://cybercemetery.unt.edu/archive/nbii/20120113005500im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_26151_1815_6640_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/geographic/central_sw_gulf/ecoregions_of_cswgcin__warm_deserts___invasive_species_spotlight__narrow_/warm_deserts___invasive_species_spotlight__wide__1.jpg)
![Image of Pecos Sunflower, courtesy of [Photo: R. Sivinski, New Mexico Rare Plants, nmrareplants.unm.edu]](https://cybercemetery.unt.edu/archive/nbii/20120113005500im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_26149_1815_6640_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/geographic/central_sw_gulf/ecoregions_of_cswgcin__warm_deserts___endangered_species_spotlight__narrow_/warm_deserts___endangered_species_spotlight__narrow__1.jpg)
