DESERT RODENTS Size Doesn’t Matter What is a Rodent Anyway? Rodentia comprises the single largest group of mammals (with the smallest members) The family Muridae contains over 1100 different species (rats, mice, voles, hamsters, etc.) Native on all continents except Antarctica Greatest diversity of form found in South America (isolated continent for most of the Cenozoic) It’s all in the teeth Rodents all have a single pair of incisors in each jaw (grow continually through life) Thick enamel layers on the front but not on the back Large gap in the tooth rows (diastema), no canines, few molars. Large/complex jaw musculature But Also Great Diversity… Most are herbivorous but some are omnivorous (eat insects too) Some diurnal, some nocturnal Can burrow, swim, or “fly” Can live solitary lifestyles or in highly social systems (like prairie dogs) Castoroides Extinct giant beaver from the Pleistocene (about the size of a bear) What is NOT a rodent Rabbits and bunnies! -They are lagomorphs (extra pair of incisors and different skeletal structure) Shrews, moles, and hedgehogs -Classified in the Insectivora Ecosystem Function Reproduce rapidly Important food source for predators Valuable in seed dispersal Key disease vectors (population control, baby) Used by people for research, food, fur, and landmine detection Desert Rodents All survive on very little water (specialized water retention) High daytime temperatures necessitate nocturnal habits Built for rapid locomotion in open spaces (super fast!) Pale colors take in less heat (and are good for camouflage) Now Some Examples Kangaroo Rat eats seeds and grasses hops on hind feet (using tail for balance) neither sweats nor pants “cute” communicates in “peeee’s,” growls, squeaks, squeals, and chuckles Long-Tailed Pocket Mouse Does not drink free water. Gets water from green vegetation Feeds opportunistically on seeds, green vegetation and insects Desert Woodrat Builds a house used for nesting, food catching, and predator escape Depends on prickly pear for water Rock outcrops, rocky cliffs and slopes Mojave Round-tailed Ground Squirrel Diurnal Hibernates in winter to avoid cold season Also sleeps through the hottest part of the summer Antelope Squirrel Also Diurnal Only rodent active during the hottest part of the day in the summer months And Everyone Wants to Eat Them Predators include the coyote, Mojave rattlesnake, mountain lion, bobcat, red- tailed hawk, golden eagle, barn owl, kit fox, badger (not a rodent) etc. Tragedy in the Desert Ah Rodents They are plentiful They are diverse They are highly evolved They are critical to ecosystem function They are cute and diseased References “Rodent.” Wikipedia. <http://en.wikipedia.org/wiki/Rodent> “Introduction to Rodentia.” http://www.ucmp.berkeley.edu/mammal/rodentia/rodentia.html Hafner, Mark S. “Density and Diversity in Mojave Desert Rodent and Shrub Communities.” Journal of Animal Ecology: (1977), Vol. 46,925-938. “Kangaroo Rats.” Desert USA. http://www.desertusa.com/aug96/du_krat.html “Desert Animal Survival.” Desert USA. http://www.desertusa.com/survive.html California Department of Fish and Game. “California Wildlife Habitat Relationship System.” Database Version 8.1. (2005).