Habitat

Most types of habitats are occupied by rodents. Some species are desert specialists. For instance, the red viscacha rat (Tympanoctomys barrerae) of the family Octodontidae occupies harsh desert habitats in parts of Argentina and demonstrates adaptations for feeding on plants with a high salt content. Kangaroo rats (Dipodomys) reveal several behavioral and physiological modifications for living in harsh desert environments, including a highly modified kidney that allows for concentration of urine and features of the nasal passage that aid in the extraction of water prior to exhaling through the nostrils. This species is active at night and occupies a closed burrow system during the day, and all the water necessary for survival is acquired through selective foraging of seeds high in water content. Other saltatorial rodents occupying similar desert habitats show strong physiological, behavioral, and morphological convergence, possessing many features analogous to the North American kangaroo rat. Squirrels are quite diverse in terms of habitat. Tree squirrels occur in most forested areas. Some species of squirrels (e.g., prairie dogs, ground squirrels, marmots) create elaborate burrow systems and can live in habitats ranging from grasslands to semidesert regions. The antelope ground squirrel (Ammo-spermophilus nelsoni) is a diurnal species that occupies desert areas in the southwestern United States. This particular species displays short activity bouts interrupted by periods in the shade where excess heat is released prior to the next foraging bout. The beaver, muskrat, and nutria prefer riparian habitats and wetlands. Some species of lemmings occur in tundra, and other microtines prefer either forest or grassland habitats. In many cases, rodents are essential components of the habitats that they occupy, and through their activities, plant communities can be modified as a result of foraging behavior, seed dispersal, and enhancing components of the soil. For instance, the plains viscacha (Lagostomus maximus) alters plant communities with forbs becoming more dominant than grasses in areas that are heavily grazed. Other studies on North American kangaroo rats have revealed significant changes in plant diversity in areas where a particular species has been removed.

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