The white-throated woodrat (Neotoma albigula) is a species of rodent in the family Cricetidae. It is found from central Mexico north to Utah and Colorado in the United States. It is primarily a western species in the United States, extending from central Texas west to southeastern California. Populations east of the Rio Grande in New Mexico and Trans-Pecos Texas, previously considered to be variants of the white-throated woodrat, have since 1988 been assigned to the white-toothed woodrat (N. leucodon).
The animal lives mostly in the Upper and Lower Sonoran life zones, occurring from pinyon-juniper woodland in higher country to desert habitats at lower elevations.
As with other species of woodrats, the white-throated woodrat constructs middens of a variety of materials such as sticks, cactus parts, and miscellaneous debris. An above-ground chamber within the midden contains a nest lined with grasses and kept free of feces. In non-rocky areas, the den usually is several feet in diameter and most commonly built around the base of a shrub that gives additional cover. In areas of rocky outcrops, crevices often are utilized, with sticks and other materials preventing free access to the nesting chamber.
Molecular data suggest that this species separated from other species of the Neotoma floridana group (Neotoma floridana, Neotoma micropus, Neotoma leucodon) about 155,000 years ago during the Illinoian Stage of the Pleistocene. This is consistent with the oldest known fossils from Slaton, Texas. This rodent is a common fossil in Southwestern cave faunas, with over 20 fossil localities of Pleistocene age known from New Mexico alone.
Distribution The ranges of the white-throated woodrat and its subspecies are from the southeastern corners of Nevada and California across southern Utah and all of Arizona to southwestern Colorado, across west Texas and south to central Mexico.
N. a. albigula (Hartley) – Northern New Mexico and northeastern Arizona south along the east side of the Sierra Madre Oriental, to southern Coahuila, Mexico. Also central Texas to western Arizona, and south along the western side of the Sierra Madre Occidental to central Sonora N. a. brevicauda (Durrant) – Utah and Colorado N. a. durangae (J. A. Allen) – Southwestern Chihuahua and central Durango, Mexico N. a. laplataensis (F.W. Miller) – Utah, Colorado, and Arizona N. a. latifrons (Merriam) – Michoacán, Mexico N. a. leucodon (Merriam) – East of the Rio Grande in New Mexico, Texas, and Oklahoma; Durango, Zacatecas, San Luis Potosí, Guanajuato, Jalisco, Aguascalientes, Querétaro, Hidalgo, and southeastern Coahuila, Mexico N. a. mearnsi (Goldman) – Arizona N. a. melanura (Merriam) – Central Sonora, Chihuahua, and Sinaloa, Mexico N. a. melas (Dice) – New Mexico N. a. robusta (Blair) – Texas N. a. seri (Townsend) – Northeastern Sonora, Mexico N. a. sheldoni (Goldman) – Northeastern Sonora, Mexico N. a. subsolana (Alvarez) – Coahuila, Tamaulipas, Nuevo León, and Coahuila, Mexico N. a. venusta (True) – Colorado River valley in western Arizona south to Sonora and Baja California, Mexico N. a. warreni – Colorado, Oklahoma, northeastern New Mexico, and Texas
In general, white-throated woodrats occupy desert grasslands, semiarid shrublands, saguaro (Carnegiea gigantea) cactus communities, pinyon-juniper (Pinus-Juniperus spp.) woodlands, interior ponderosa pine (P. ponderosa var. scopulorum) forests, and Madrean evergreen woodland (Pinus spp.-Quercus spp.).
Preferred habitat The white-throated woodrat occupies a variety of plant communities from sea level to 9,200 feet (2,800 m) but is most common in Sonoran and Chihuahuan desert grassland and desert shrub habitats. The white-throated woodrat is generally associated with creosotebush, mesquite, cacti (particularly prickly-pear and cholla (Cylindropuntia spp.)), catclaw acacia, and paloverde. These plants provide cover and succulent plant food (>50% water by weight) (see section "Food habits"), the 2 most critical habitat requirements for white-throated woodrat.
White-throated woodrats prefer habitat with low tree canopy cover, high shrub and rock cover, and coarse woody debris. When available, natural and human constructed riparian habitat may be used by white-throated woodrats.
Tree, shrub, and rock cover In several studies in Arizona, white-throated woodrats preferred low tree cover and high shrub, rock, and litter cover.Boyett, William D. 2001. Habitat relations of rodents in the Hualapai Mountains of northwestern Arizona. Oshkosh, WI: University of Wisconsin Oshkosh. Thesis In ponderosa pine-Gambel oak habitat in the Hualapai Mountains in Arizona, white-throated woodrat presence was negatively associated with high tree cover and high herbaceous cover and positively associated with high shrub and rock cover. On plots where white-throated woodrats were trapped, mean tree canopy cover ranged from 30% to 57%, mean herbaceous cover ranged from 2% to 10%, mean shrub cover ranged from 5% to 19%, and mean rock cover ranged from 3% to 14%.
In desert riparian floodplain habitat at Montezuma Castle National Monument, Arizona, white-throated woodrats were more abundant in an active riparian channel and floodplain that had lower tree cover and a higher percentage of forbs and rocks than a mesquite bosque. The active riparian channel and floodplain was dominated by desert willow, velvet ash (Fraxinus velutina), Arizona sycamore (Platanus wrightii), and velvet mesquite. The mesquite bosque was dominated by velvet mesquite, catclaw acacia, and broom snakeweed.
In pinyon-juniper woodlands in Grant County, New Mexico, total overstory density was more important than overstory species composition in influencing white-throated woodrat occurrence. The greatest densities of white-throated woodrat houses were on plots containing 376 to 750 overstory plants per hectare:
White-throated woodrats prefer rocky areas within forested habitat, including ledges, slides, cliffs, and canyons. In a ponderosa pine forest on the Beaver Creek Watershed in the Coconino National Forest, all white-throated woodrats were captured within of rocky habitat. In ponderosa pine-Gambel oak habitat in the Hualapai Mountains, white-throated woodrat presence was positively associated with high (3% to 19%) rock cover.
Riparian The white-throated woodrat is well-adapted to xeric habitats, but may also be found in riparian areas. They may utilize both natural and human-constructed areas when available.
Natural At Montezuma Castle National Monument, white-throated woodrat abundance was generally greater in an active riparian channel and floodplain than a mesquite bosque that was above the channel and floodplain and not subject to flooding. The active riparian channel and floodplain was dominated by desert willow, velvet ash, Arizona sycamore, and velvet mesquite. The mesquite bosque was dominated by velvet mesquite, catclaw acacia, and broom snakeweed. Despite greater abundance of white-throated woodrat in the active riparian channel and floodplain, body weights of male white-throated woodrat were significantly (P<0.05) higher in the mesquite bosque, suggesting that it was "higher quality" habitat.
Although preferred habitat differed between male and female white-throated woodrats on the Santa Rita Experimental Range, Arizona, both genders showed some preference for riparian woodland typified by Arizona white oak and netleaf hackberry:
Human constructed Construction of water developments in xeric habitat in Arizona may provide habitat and water for white-throated woodrats. On the Cabeza Prieta National Wildlife Refuge in southwestern Arizona, white-throated woodrats were trapped most often in velvet Mesquite Bosque thickets that grew closest to a human constructed water development. White-throated woodrats were trapped least often in habitat dominated by creosotebush and furthest away (distance not given) from the water development. No white-throated woodrats were trapped at a nearby dry water development.
White-throated woodrats also occupied a human constructed desert riparian habitat at No Name Lake on the Colorado River Indian Reservation on the Arizona side of the Colorado River. The area was cleared of nonnative tamarisk (Tamarix spp.) and 80% of the area was planted with native Fremont cottonwood and honey mesquite. Other vegetation included Goodding's willow Salix gooddingii, blue paloverde (Parkinsonia florida), big saltbush (Atriplex lentiformis), and California fan palm (Washingtonia filifera).
Coarse woody debris Habitat with abundant coarse woody debris is preferred by white-throated woodrats for cover (see Cover). In pinyon-juniper woodlands at the Piñon Canyon Maneuver site near Trinidad, Colorado, white-throated woodrats were captured most often in areas with coarse woody debris. In an actively flooded riparian channel and floodplain at Montezuma Castle National Monument, white-throated woodrat occurrence was significantly (P<0.05) greater in areas containing coarse woody debris than areas without coarse woody debris.
In a pinyon-juniper woodland in the Gila National Forest, New Mexico, white-throated woodrats responded favorably to mechanical treatments that increased the amount of coarse woody debris. Of 4 treatments (untreated; bulldozed/piled/burned; bulldozed; and thinned), white-throated woodrats were most abundant on bulldozed plots and thinned plots, where slash accumulations were 2.5 to 3 times greater than on other plots. On bulldozed plots, Colorado pinyon, one-seed juniper, and alligator juniper trees were pushed over and left in place. On thinned plots, Colorado pinyon and juniper were cut to a minimum spacing of and left in place. The table below shows total numbers of woodrats on 4 plots:
White-throated woodrat density increased in a pinyon-juniper woodland in Grant County, New Mexico, where trees were uprooted and piled to improve livestock grazing. The felled trees provided white-throated woodrats with cover and building materials.
Cover requirements White-throated woodrats must rely on self-constructed, ground-level shelter to lower the energetic costs of thermoregulation in extreme environments. White-throated woodrats typically use 2 types of shelter: houses, constructed at the base of plants, and dens in rock crevices. Other shelter types include holes and crevices in cutbanks along washes, burrows of other animals, piles of coarse woody debris, and human habitations and structures. Houses and dens are often maintained by successive generations of white-throated woodrats.
Houses are built by white-throated woodrats at the base of trees, shrubs, and cacti or in piles of coarse woody debris. White-throated woodrats prefer to construct houses at the bases of plants that provide both adequate shelter and food. Houses are constructed of various materials and are typically 3 to 10 feet (1–3 m) in diameter and up to 3 feet tall. Dens function as houses but are located in rock crevices, rock fissures, and under boulder piles.
Houses and dens enclose a system of runways and chambers, including the white-throated woodrat's nest. The nest averages in diameter and is composed of soft, fine material including grass, shredded prickly-pear fibers, or juniper bark.
Building materials