Cactus mouse

Abstract: SUMMARY. In a survey of 52 rodents of 25 species from Grand Canyon National Park, Arizona and its vicinity, the following species of Eimeria are described: E. tamiasciuri n. sp. from the red or spruce squirrel, Tamiasciurus hudsonicus; E. lateralis n. sp. and Eimeria sp. from the mantled ground squirrel, Citellus lateralis; E. eutamiae n. sp. from the cliff chipmunk, Eutamias dorsalis; E. thomomysis n. sp. from the pocket gopher, Thomomys bottae; E. perognathi n. sp. from the rock pocket mouse, Perognathus intermedius; E. albigulae n. sp. from the white-throated woodrat, Neotoma albigula; E. operculata n. sp. from Stephens' woodrat, Neotoma stephensi; E. peromysci n. sp. and E. arizonensis n. sp. from the pinon mouse, Peromyscus truei; E. eremici n. sp. from the cactus mouse, Peromyscus eremicus; and E. onychomysis n. sp. from the northern grasshopper mouse, Onychomys leucogaster.

Abstract: Sexual isolation of closely related forms through mate selection has been intensively studied in Peromyscus by means of the jump cage design initially used by Blair and Howard (1944). Usually four mice, one male and one female of each of two kinds are placed in a four-compartment cage and their daily positions recorded. Subsequent work using the jump cage dealt with discrimination between different subspecies within a species (Blair, 1954; Harris, 1954) or different species within one cenospecies (Blair, 1953; Bradshaw, 1956; Clark, 1952; McCarley, 1953; Tamsitt, 1961). Two main problems are associated with the jump cage experiments. One male often dominates or even kills the other; consequently, information is lacking on any preference that the dominated individual may have shown for a female. The role played in mate selection by the dominated male is largely unknown. Harris (1954) modified the jump cage design by using only one male thus avoiding the problem of male domination. The second problem is the reduction in space in the jump cage, which increases the amount of behavioral interaction to a level greater than that found in nature. The effect of increased behavioral interaction upon sexual isolation is not known. This investigation was designed to minimize or eliminate the above problems and to answer two questions. First, do males of P. eremicus (cactus mouse) and P. californicus (California

Abstract: Characterizing traits critical for adaptation to a given environment is an important first step in understanding how phenotypes evolve. How animals adapt to the extreme heat and aridity commonplace to deserts represents is an exceptionally interesting example of these processes, and has been the focus of study for decades. In contrast to those studies, where experiments are conducted on either wild animals or captive animals held in non-desert conditions, the study described here leverages a unique environmental chamber that replicates desert conditions for captive Peromyscus eremicus (cactus mouse). Here we establish baseline values for daily water intake and for serum electrolytes, as well as the response of these variables to experimental dehydration. In brief, P. eremicus' daily water intake is very low. It's serum electrolytes are distinct from many previously studied animals, and its response to dehydration if profound, though not suggestive of renal impairment in the face of profound dehydration, which is atypical of mammals.

Abstract: We studied the diet of two species of owls, and assessed the rodents communities and their relative densities from March 1996 through February 1997 in the Mapimi Biosphere Reserve, Durango, Mexico: Great Horned Owl (Bubo virginianus) and Barn Owl (Tyto alba). The objectives were to understand the predator-prey relationships by comparing the availability and use of rodents by these owls. We analyzed 146 regurgitated pellets of five Great Horned Owl and 63 of four Barn Owl, both of seven samples. This species had different prey items: Great horned owls consumed eleven rodents species, while Barn owls consumed only six. In both bird’s diets, arthropods and shrews were detected, and Great Horned Owl furthermore consumed ferns and reptiles. Based on the availability of rodents, the Great Horned Owl preferred eight rodent species: Silky Pocket Mouse, White-throated Woodrat, Western harvest mouse, Merriam's Kangaroo Rat, Desert Pocket Mouse, Nelson's Kangaroo Rat, Nelson's Pocket Mouse and Cactus Mouse. Barn Owl preferred five prey species: Silky Pocket Mouse, Desert Pocket Mouse, Nelson's Kangaroo Rat, Merriam's Kangaroo Rat and Cactus Mouse. Diets of the two raptors have little overlap, except during reproduction and chick rearing. Food habits of these birds appear to be dependent upon the foraging habitat: Great Horned