In previous articles O. arenicola was combined with O. torridus; however, recent genetic work has recognized Mearns grasshopper mouse as a separate species. In southwestern New Mexico, O. arenicola was found to be specifically distinct from O. torridus when a contact zone between the two species was found and no hybridization or back crosses, based on karyotypes, occurred.
Members of the genus Onychomys are known to make different vocalizations in different social contexts, including a "chit" sound during aggression, and a soft "chirp" during mating. This indicates that acoustic communication is important in this species. Fighing behavior most certainly could be considered a form of tactile communication. Tactile communication is probably also important between a mother and her young and between mates. It is likely that there are also visual and chemical signals passing between conspecifics, as is common in most mammals.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
No special conservation issues are currently recognized, but due to the geographic isolation and ecology of this species, habitat loss, fragmentation, and degradation could significantly influence population dynamics.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
When the supply of food is low, grasshopper mice have been known to eat and or cache plant matter. This may result in negative affects on human agriculture.
Negative Impacts: crop pest
Due to their strong territoriality and predatory nature, O. arenicola can be beneficial to people. O. arenicola can be beneficial by negatively impacting populations of small rodents and insects, species that may have negative affects on human practices such as agriculture.
Members of the genus Onochomys are reported to make docile and fascinating pets, indicating that these animals present some value to the pet trade.
Positive Impacts: pet trade ; controls pest population
As a predator, O. arenicola probably helps to regulate certain insect populations. As a prey species, abundance of O. arenicola may help to regulate populations of its predators. However, because it does not occur at very high densities, it is not likely to be a very important component of the diet of any predator.
Due tot heir seed caching behavior, it is possible that these animals also help to disperse seeds of certain plants.
Ecosystem Impact: disperses seeds
The feeding habits of Mearns' grasshopper mouse are similar to those of Onychomys leucogaster.
Their diet consists mostly of other animals (about 90%) but also a variety of plants (10%). They feed mostly on insects (including grasshoppers, scorpions, beetles, and crickets), but will attack and eat other small mammals, including other grasshopper mice.
The stomach of this species is interesting, because the peptic and muriatic glands are disposed in a special pocket, perhaps to protect them from damage by the chitin in their food. They are reported to cache food.
Animal Foods: birds; mammals; reptiles; insects; terrestrial non-insect arthropods
Plant Foods: seeds, grains, and nuts
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Insectivore )
Onychomys arenicola, Mearns grasshopper mouse, has a limited distribution in the southwestern portion of North America. It can be found in south-central New Mexico, extreme western Texas, and northeastern Mexico.
Biogeographic Regions: nearctic (Native )
Mearns' grasshopper mouse habitat in Texas includes low, arid, sandy or gravelly desert areas where the principle vegetation consists of creosote brush, mesquite, yucca, lechuguilla, and condalia. In New Mexico it is associated with desert grasslands dominated by black grama and mesa dropseed with occasional soaptree yucca and Mormon tea, annual and perennial forbes and grasses.
This mouse is found at elevations ranging from 1,340 m to 1,580 m.
Range elevation: 1340 to 1580 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune
Grasshopper mice kept in pairs in captivity reached an average age of barely four years, five years at the most. The lifespan of thse mice in the wild has not been reported.
Range lifespan
Status: captivity: 4 to 4 years.
Onychomys arenicola is a small mouse with a fat tail. It has a cinnamon-pink or grayish dorsal side and a white ventral side. At the base of each ear on the front side, there is usually a white or grayish tuft of fur. The nose, cheeks and sides are white. The tail of this mouse is sparsely haired and bicolored, with dark above and white below. The tail makes up more than about 1/3 of total length of the mouse, and is 2.5 times as long as the hind foot length. This species is similar to Onychomys leucogaster, but smaller, with a relatively longer tail and smaller teeth. It is also similar in appearance to Onychomys torridus, but is smaller in every measurement except the nasal length of the skull.
Juveniles look like adults, but their upper parts are bluish-gray.
The total length of adults averages 146 mm, the tail averages 52 mm, and the hind foot averages 21 mm. The weight of adult males ranges between 24 and 30 g, with an average of 26.5 g. Females are lighter, typically weighing between 22 and 28 g, and averaging 25 g.
Range mass: 22 to 30 g.
Average mass: 25-26.5 g.
Average length: 146 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Onychomys arenicola avoids predators by spending daytime hours inside burrows. Their most active time coincides with little to no moonlight; that is before the moon rises, after it sets, during new moon phases, or during overcast conditions.
Given its habitat and nocturnal lifestyle, the most likely predators of this species are owls, snakes, and carnivorous mammals like coyotes and bobcats.
Known Predators:
The mating system of these mice has not been reported. They are presumed to be polygynous, although in congeneric species, males and females are known to associate in pairs throughout the year, and may be monogamous.
Breeding begins in late January or early February and continues into September. Gestation period is 26 to 35 days. Litter size varies between two and seven. Half-grown young have been captured in April, June, July, and August, suggesting these mice produce two to three litters per year.
Although data are scarce for O. arenicola, in general, mice in this genus weigh about 2.6 g at birth. Their eyes open at about 2 weeks of age. Young mice are typically weaned around 3 weeks of age.
Females in this genus become sexually mature at seven to eight weeks of age. A young female can give birth to her first litter at four months of age.
Breeding interval: It is likely that these mice breed approximately three times per year, all in the spring and early summer months.
Breeding season: Breeding occurs from January through September.
Range number of offspring: 2 to 7.
Range gestation period: 26 to 35 days.
Average weaning age: 3 weeks.
Average age at sexual or reproductive maturity (female): 4 months.
Average age at sexual or reproductive maturity (male): 4 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
The young are born without much ability to move around. Their eyes are closed. Females nurse their offspring and care for them in a nest. It is not known whether the male participates in parental care.
Parental Investment: altricial ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Mearns's grasshopper mouse or the Chihuahuan grasshopper mouse (Onychomys arenicola) is a grasshopper mouse found in southwestern New Mexico, West Texas, and north-central Mexico. They are similar to Onychomys torridus, but differ in karyotype and size. This mouse is smaller in every regard except for the nasal length of the skull.[3]
They are found in semiarid habitat, prairie, and scrub. They feed largely on insects and other invertebrates, including scorpions. They also feed on small muroid rodents and pocket mice.
Mearns's grasshopper mouse or the Chihuahuan grasshopper mouse (Onychomys arenicola) is a grasshopper mouse found in southwestern New Mexico, West Texas, and north-central Mexico. They are similar to Onychomys torridus, but differ in karyotype and size. This mouse is smaller in every regard except for the nasal length of the skull.
They are found in semiarid habitat, prairie, and scrub. They feed largely on insects and other invertebrates, including scorpions. They also feed on small muroid rodents and pocket mice.
