White-Throated Woodrat, Neotoma albigula
The white-throated woodrat (Neotoma albigula) can be found in a range that extends from Central Mexico in the South to Colorado and Utah in the North. Its western range extends from Texas to southeastern California, but it does not occur in the eastern areas of the United States. Populations of these rats occurring east of the Rio Grande in New Mexico and Trans-Pecos Texas are classified as the white-toothed woodrat. The white-throated woodrat holds fifteen subspecies that occur throughout its range.
The white-throated woodrat prefers a habitat within Chihuahuan and Sonoran desert grasslands and shrub lands. It is commonly found living in acacia, paloverde, mesquite, cacti, catclaw, and creosotebush, because these plants provide adequate cover, water, and food resources. It prefers areas with low tree canopy, rock, and high shrub cover. Studies conducted in Arizona and other areas of this rat’s range show that, depending on the type of habitat, cover preferences can vary.
The white-throated woodrat must have cover in order to regulate and keep a healthy body temperature. They can be found residing in either house like structures, built under plants or in dens created in rocks. They will also live in abandoned burrows, crevices and holes in cutbanks near washes, human created shelters, and piles of wood debris. Many generations can live in these burrows, maintaining them to make them last longer. The shelters are typically built using many materials and are three to ten inches in length, and up to three feet tall. They contain many rooms and runways, including a nest. The nests are usually made of soft plant materials and can reach a diameter of eight inches.
Depending on each habitat, the white-throated woodrat will build nests out of many materials. In woodlands, it will use sticks and other tree materials, while in deserts it will gather pieces of cacti, acacia, yucca, and mesquite to build homes. In desert regions, cacti is the prefers building material. These rats will also use bones, feces, and human objects in homes. One study conducted on one hundred white-throated woodrat homes located in the Santa Rita Experimental Range, showed that seventy-five materials were used to build the homes. Most materials are gathered close to the home. IN some areas, the materials used could not always be found.
The white-throated woodrat will use plants that occur in its range as a base for their homes. In Arizona, Utah, Texas, and California, these woodrats used mesquite for their homes, as these plants dominate the landscape. In San Diego County, California, where creosote bush and mesquite dominated, all of the woodrats were found under honey mesquite. Instead of the average three to ten inch tall mesquite, the rats preferred twenty to twenty-six foot honey mesquite, most likely because they provide better shelter and more food. Most likely, these rats will use whatever plant is most abundant within their habitat to build a home under.
Some habitats do not provide adequate plant shelter for the white-throated woodrat. In southeastern Utah, in deserts and juniper woodlands, these rats preferred to make homes under boulders. In Saguaro National Monument, where the plants where mostly dry and brittle, all one hundred dens located were found under boulders. Other sheltering areas include riverbanks, subterranean areas, and caves. At Carrizo Creek in San Diego County, where creosotebush and mesquite were abundant, the rats chose to live near riverbanks and in subterranean burrows most likely made by kangaroo rats. It is thought that they chose the homes because of a lack of good plant materials to build with, harsh weather, or the ease of burrowing in the loos sand under the rocks.
The white-throated woodrat reaches an average body length of 12.9 inches and a weight of 6.6 ounces for females and 7.9 ounces for males. Unless females are nursing young, each rat will live alone. They are nocturnal and do not hibernate. According to Newton, the lifespan of this rat is 72 months, but according to Brown and Zeng, it only lives for up to 45 months.
The mating season for the white-throated woodrat varies depending on its location. In Big Bend National Park, Texas, it is thought that mating can occur year round, but occurs at least during the months of January to November. In Arizona, mating occurs between the months of January to August, and in California, it is thought that this rat will mate between the months of February to May. In every area of its range, the white-throated woodrat is polygynous.
After approximately thirty-eight days of pregnancy, one or two young are born in early summer or spring. Young are weaned at sixty-two to seventy-two days after birth, but this varies in the white-throated rat’s subspecies. Young will reach sexual maturity at up to 176 days after birth.
The diet of the white-throated woodrat consists mainly of plant materials, but it is an opportunistic feeder. It eats mainly plant materials, like fruit, seeds, flowers, and greens, and they will eat small amounts of beetles, grasses, and reptiles. Among the most common plants eaten are stems, cacti flowers, fruits, and seeds. Despite this varied diet, food types consumed depend on availability and season. In some areas, these rats may store food.
In Great Basin, located in northern Arizona, where juniper woodland and desert scrub were abundant, the rat’s diet was varied, while in the Santa Rita Experimental Range found in Arizona, the rats ate mainly mesquite and cacti. The main source of water for these rats can be found in xerophytic plants that it eats, like cacti. In Organ Pipe National Monument, woodrats depend on buckhorn cholla, jumping cholla, teddybear cholla, and goatnut for hydration. White-throated woodrats located in Coconino County received their hydration from evergreen species.
There are many common predators of the white-throated woodrat include bobcats, weasels, coyotes, ring-tailed cats, great-horned owls, and rattlesnakes. This rat appears on the IUCN Red List with a conservation status of “Least Concern”.
Image Caption: Neotoma albigula (White-throated woodrat). Credit: Roger W. Barbour/Wikipedia