Burrowing rodents

Abstract

Burrowing rodents have unusually disproportionate effects on rangeland ecosystems because they (1) engineer their environment through burrow construc-tion and modification of vegetation structure, (2) influence ecosystem processes including aboveground plant production, nutrient cycling rates, and water infiltra-tion patterns, (3) alter plant community composition, and (4) provide a prey base for a diverse array of predators. In some cases, engineering effects create habitat for certain faunal species that inhabit burrows or colonies of these rodents. We review the ecology and management of burrowing rodents that function as ecosystem engi-neers in western North America, which includes prairie dogs (five species in the genus Cynomys), ground squirrels (11 species in the genera Otospermophilus, Poliocitellus, and Urocitellus), pocket gophers (16 widespread species in the genera Cratogeomys, Geomys, and Thomomys), and kangaroo rats (eight widespread species in the genus Dipodomys). Effects of burrowing rodents on vegetation structure, species composi-tion, and nutrient content vary with diet, degree of sociality, body size, and hibernation patterns, and potentially have significant effects on coexisting large grazers, including domestic livestock. Diets of prairie dogs overlap substantially with livestock. Impacts on ranching enterprises can vary with their abundance and seasonally, and may be greatest when burrowing rodents reduce dormant-season forage availability. Ground squirrel, pocket gopher, and kangaroo rat interactions with livestock vary among species in relation to their diet, degree of coloniality, and population density. All prairie dog and ground squirrel species are affected by outbreaks of plague caused by Yersinia pestis, a non-native disease. Plague and population control via roden-ticides are the primary factors determining the distribution and abundance of these species. In contrast, pocket gophers and kangaroo rats are unaffected by plague. Management and conservation efforts that enable burrowing rodents to coexist with livestock across broad landscapes will likely be essential for the conservation of a unique suite of bird, mammal, herpetofaunal and arthropod species that depend on them as prey or on their engineering activities for habitat.