Grasshopper Mice Flashcards
What species and genus of grasshopper mice are most commonly studied?
Onychomys torridus and O. leucogaster
What is unique about grasshopper mice?
Among most carnivorous of all rodents.
Describe grasshopper mice.
Weigh 30-60 grams. Gray to brown dorsal coat, white ventral fur and distal tail tips. Modifications of jaw architecture that promote large bite forces for preying upon large prey.
Where are grasshopper mice found?
O. torridus in SW US and northern Mexico. O. leucogaster from eastern Washington and southern Manitoba to extreme northern Mexico.
In what environments do grasshopper mice live?
Short-grass prairies and desert scrub. Live in any shelter they can find at ground level although they are good climbers. Nest may be in burrow taken over from another rodent.
Are grasshopper mice social?
Population density is low. Female-male pairs may associate all year, but in captivity, individuals of the same sex are very aggressive to one another.
What are grasshopper mice used to study?
Behavior. Transmission of Lyme disease in urine.
Why are grasshopper mice important in plague research?
O. leucogaster serves as an alternate host, causing plague to persistent in prairie dog colonies for prolonged periods.
When are grasshopper mice active?
Both species are nocturnal and active throughout the year.
Describe reproduction in grasshopper mice.
Can breed throughout the year, but most activity occurs from May to September. Females have a 5-7 days estrous cycle and 26-37 day gestation.
How many litters can grasshopper mice produce?
Several in the wild, up to 12 litters per year in captivity. Litter size ranges from 1-6, and is higher in O. leucogaster.
Describe weaning and sexual maturity of GM pups.
Weaned at 3 weeks and reach sexual maturity at 2-5 months in O. leucogaster and as early as 6 weeks in O. torridus.
Describe the midventral sebaceous gland.
Larger in males than females, castration causes involution. Secretions used for communication - territorial marking, gonadal status, or pup identification.
What does the northern grasshopper mouse (O. leukogaster) require to prevent an oily coat?
Dust baths. Similar to kangaroo rats, degus, and chinchillas.
What is the diet of GM in the wild?
Predominantly grasshoppers, beetles, and small vertebrates, including other rodents. O. torridus prey exclusively on scorpions and are physiologically resistant to scorpion envenomation following natural stings
What are GM fed in captivity?
O. torridus can be maintained on fresh mouse carcasses supplemented with seeds and ad libitum water.
O. leukogaster fed commercial mouse ration supplemented with grain mixture and canned dog food.
Does cross fostering in GM require the same species?
No, Southern grasshopper mice can be cross-species fostered on white-footed mice (Peromyscus).
How does hearing in GM compare to other desert rodents?
Do not hear low frequencies as well as do other desert rodents such as kangaroo rats and gerbils.
The carnivorous behavior of O. leucogaster appears to promote strong selection for resistance to what disease?
Plague, in areas where they are naturally exposed.
What condition do GM experimentally/natural exposed to Lyme Borrelia burgdorferi spirochetes develop? What other species develops the same condition?
Cystitis. Peromyscus leucopus
What spontaneous condition can Southern GM develop in captivity? What is it correlated to?
Convulsive seizures, similar to that seen in Mongolian gerbils. Preweaning parental environment has a sig influence on the prevalence.
