Brush Mouse
Encyclopedia
The brush mouse is a species of rodent
in the family Cricetidae
. It is found in mountainous areas of Mexico
and the western United States
at altitudes over 2000 metres (6,561.7 ft).
Vegetation in brush mouse habitats may vary from location to location, but brush mice are consistently captured in areas with medium to high densities of shrubs and tree cover under 16 feet (5 m) in height. In California, mature chaparral (cover ≥50%) appears to provide more suitable habitat for brush mice than young, open chaparral (cover <50%). Similarly, in Arizona, Duran captured brush mice most frequently in shrub live oak and birchleaf mountain-mahogany (Cercocarpus betuloides) understory habitats with 45% to 50% plant cover. Fewer brush mice were captured in habitats with less plant cover. Holbrook observed that after vegetation crowns were removed in a manzanita (Arctostaphylos spp.)-oak shrubland, brush mice avoided the newly-opened space. In another study, brush mice were strongly restricted to habitats in which gaps between rocks or ceanothus (Ceanothus spp.) on the site were less than 4 feet (1.2 m).
In addition to shrub density, the height of cover appears to influence brush mouse distribution within a site. An average understory height of 5–6.5 feet (1.5–2.0 m) was preferred by brush mice over lower understory cover. In another study, brush mouse presence was positively correlated with microhabitats of shrub cover up to 10 feet (3 m) tall, logs over 3 inches (7.5 cm) in diameter, and understory trees 10–33 feet (3–10 m) in height, but negatively correlated with grass-forb microhabitats.
Brush mice are also commonly captured at locations with a high proportion of rock cover and/or slash piles in habitats characterized by chaparral-mountain shrub, oak/shrub, oak-juniper-pinyon pine, juniper-pinyon pine, and oak-pine communities, as well as riparian habitats. The brush mouse in Texas has been found in all major habitats present (desert, grassland, riparian, and montane) although it is typically associated with rock outcrops within these habitats. Riparian sites with abundant brush mouse populations had high shrub cover, high frequency of debris piles with low grass, litter, and tree cover. In a Mexico study, a canyon was dominated by exposed rock, grasses, pines, hardwoods, and brush. In western Texas, brush mice favored fallen logs and brush piles. Modi discovered that brush mice were common in riparian zones dominated by pecan (Carya illinoensis), American sycamore (Platanus occidentalis) and live oak (Quercus virginiana), in an oak community with a partially open canopy and dense understory, and in a pine forest with little understory and scattered boulders. In New Mexico, brush mouse populations were significantly higher (P<0.05) on sites that were bulldozed or thinned (98 and 115 captures, respectively) than untreated or bulldozed and burned sites. Populations were lowest on sites that had not been treated (45 captures). Sites that had increased slash from bulldozing and burning had more brush mice (57 captures) than the untreated sites, but the difference was not significant (P>0.05). No influence of canopy cover on brush mice was observed in the study.
Besides high tree, shrub, and rock densities, brush mice appear to prefer locations with low grass cover. At the same time, grasses are often present in the understory indicating that grasses do not exclude brush mice. Brush mice utilized grazed and ungrazed pastures and ceanothus plots, but they were concentrated around rocky outcrops and vegetation continuous with the rock outcrops. No brush mice were captured in the grasslands more than 20 feet (6 m) from rocks, shrubs, or trees. Litter depth also appears negatively correlated to brush mouse presence. For instance, brush mice in Arizona were captured in litter depths of only 0.9 inches (2.4 cm).
Brush mice also utilize fire-affected habitats. In one study, brush mice were captured in burned and unburned chaparral as well as burned and unburned pine-oak forest. The highest number of captures were recorded in unburned forest while the lowest captures occurred in the unburned chaparral. These results are somewhat inconsistent with other observations which show the brush mouse favoring dense chaparral habitat. Small mammal capture data in the study were collected from 14 months to 3 years after fire. The time frame of sampling after fire may influence the perceived response of the brush mouse to postfire habitats.
Elevation, in addition to habitat characteristics, may play a role in habitat suitability in some areas. For instance, in the northern Sierra Nevada of California, brush mice were captured in brush habitats at 3,500–5,000 feet (1,000–1,500 m), but not at 6,500 feet (2,000 m). Aspect may influence the distribution of brush mice on a site as well. For example, in New Mexico, 51% of all brush mice captured were taken on south-facing slopes, 24% on west-facing slopes, with 13% and 12% of mice captured on east- and north-facing slopes, respectively. The south-facing canyon slopes may provide more cover for brush mice due to higher numbers of shrubs.
Although brush mice are found on a variety of slopes, including flat mesas and gradual slopes, they seem to prefer locations with very steep slopes, such as hillsides, mountain sides, and canyons (including some slopes with >45% gradient) over more gradual slopes in the same areas. Findley reported that brush mice were captured on hillsides in an oak/sacahuista (Nolina spp.) community. In another study, brush mice were common in canyon bottoms, on hillsides, and in arroyos (water channels in arid regions) characterized by oak woodlands. Brush mice have also been captured along the sides of brush covered canyons and burned slopes of an oak/brush association.
A study utilizing radiotelemetry and trapping data in Arizona estimated mean home range size for male brush mice at 0.72–1.6 acres (0.29–0.64 hectare), and 0.32–0.79 acre (0.13–0.32 hectare) for females. In another study at the same location, home ranges for male brush mice ranged from means of 1.2–1.5 acres (0.47–0.62 hectare) and for females, means of 0.64–1.2 acres (0.26–0.49 hectare). Mean home range for male and female brush mice in Arizona, based on radiotelemetry, was 0.30 acre (0.12 hectare).
In a New Mexico study, 27% of brush mice captured were taken around rocky areas, 10% under Gambel oak (Q. gambelii), 9% under juniper, and 7% each around woodpiles and sacahuista. Less frequently, brush mice were taken under or around pinyon pine, gray oak (Q. grisea), Apache plume, rabbitbrush, mountain-mahogany, white fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii), locust (Robinia spp.), prickly-pear, cholla (Opuntia spp.), chokecherry (Prunus spp.), bricklebush (Brickellia spp.), and grape (Vitis spp.).
In southern California, brush mice were captured on leaf mold in an oak hardwood association of coast live oak, white alder (Alnus rhombifolia), whiteflower currant, and sumac (Rhus spp.). They were also trapped under logs and dense vegetation and on wet seepage slopes next to a creek. In coastal California, brush mice were captured primarily under coast live oak, false-willow (Baccharis douglasii), California buckeye, and California bay.
Fallen logs and rock outcrops provide nest sites for the brush mouse. They may also construct nests in tree hollows and underground burrows. Brush mice living in mine shafts or caves build nests similar to those of goldfinches. Davis noted that the brush mouse nest is a "globular structure" and is constructed primarily of dried grasses within natural cavities. Brush mouse nest sites in California were found on sites with a high density coast live oak (Q. agrifolia) overstory and an open understory with low vegetation and ground cover.
). Understory and other herbaceous species include bulrushes (Scirpus
spp.), fourwing saltbrush (Atriplex canescens
), and rubber rabbitbrush (Chrysothamnus nauseosus
). Whiteflower currant (Ribes indecorum
), California bay (Umbellularia californica), black sage (Salvia mellifera), laurel sumac (Malosma laurina), and deerweed (Lotus scoparius
) may also be present. Understories may also include exotic annual forbs and grasses such as mustard (Brassica spp.), oats (Avena spp.), and brome (Bromus spp.).
), and shrub live oak (Quercus turbinella
). Shrub associates include evergreen sumac (Rhus virens), skunkbush sumac (Rhus trilobata
), roundleaf snowberry (Symphoricarpos rotundifolius
), New Mexico locust (Robinia neomexicana), common hoptree (Ptelea trifoliata), fendlerbush (Fendlera
rupicola), Carruth's sagewort (Artemisia carruthii), catclaw acacia (Acacia greggii
), broom snakeweed (Gutierrezia sarothrae
), red barberry (Mahonia haematocarpa
), netleaf hackberry (Celtis reticulata
), and wait-a-minute (Mimosa
aculeaticarpa var. biuncifera). Herbaceous and succulent species in brush mouse habitats include Wheeler sotol (Dasylirion wheeleri
), sacahuista (Nolina
microcarpa), Palmer agave (Agave
palmeri), goldenrod (Solidago spp.), lupine (Lupinus spp.), prickly-pear (Opuntia
spp.), and ocotillo (Fouquieria splendens). Grasses found in brush mouse habitat include Lehmann lovegrass (Eragrostis lehmanniana), bottlebrush squirreltail (Elymus elymoides
), and other annual and perennial bunchgrasses.
spp.), Apache plume (Fallugia paradoxa), fourwing saltbrush, common hoptree and crispleaf buckwheat (Eriogonum
corymbosum) in addition to a pinyon-juniper-mountain-mahogany (Pinus
-Juniperus-Cercocarpus spp.) overstory. Texas plant associates include Pinchot juniper (Juniperus pinchotii
), algerita (Mahonia trifoliolata
), clapweed (Ephedra
antisyphilitica), featherplume (Dalea
formosa), and prickly-pear (Opuntia
spp.).
Brown reported that brush mice reach sexual maturity at 12–19 weeks. However, Clark reported that female brush mice may reach sexual maturity in approximately 5–9 weeks. In Arizona, females born in late May or June were found pregnant during August of the same year. In western Texas, Arizona, southern Utah, and Mexico, breeding appears to occur nearly year-round. However, in northern California, Jameson found that breeding in brush mice peaked twice each year, once in late spring and again in late summer. This result may be related to food availability.
Female brush mice carry 1–6 embryos each with an average of 3–4 embryos. Lactating females may become pregnant, although lactation may slow the development of embryos in Peromyscus species. Bradley and Schmidly reported that the gestation period of the brush mouse is around 23 days. Females may have multiple litters per year. The amount of time between litters is likely similar to other Peromyscus species and may be 25–31 days. Young are weaned at 3–4 weeks of age.
Brush mice have a promiscuous mating system. Four out of 7 litters in a California study were fathered by several males. Males and females did not share nests and mating pairs did not remain together for long periods of time.
Few Peromyscus spp. mice live longer than 6 months in the wild, but individuals may live up to 4–5 years in captivity.
Acorns are commonly eaten by brush mice wherever they are available. Arthropods and cutworms (Protorthodes rufula) are also eaten throughout the year. A variety of fruits and seeds from Douglas-fir, ponderosa pine (Pinus ponderosa), pinyon, California buckeye, manzanita (A. patula and A. viscida), silktassel (Garrya spp.), oneseed juniper (Juniperus monosperma), hackberries (Celtis spp.), New Mexico groundsel (Senecio neomexicanus var. neomexicanus), trailing fleabane (Erigeron flagellaris), annual sunflower (Helianthus annuus), broom snakeweed, common dandelion (Taraxacum officinale), western yarrow (Achillea millefolium), white sweetclover (Melilotus albus), threenerve goldenrod (Solidago velutina), prickly-pear, desert wheatgrass (Agropyron desertorum), Kentucky bluegrass (Poa pratensis), and blue grama (Bouteloua gracilis) are eaten throughout the year when available. Other plant parts, such as leaves, stems, flowers, pollen cones and new sprouts are typically eaten in lower quantities than other foods. Fungi are typically consumed when other foods are scarce. Infrequently, stomach contents of brush mice contained pieces of mammals, birds, and fence lizards (Sceloporus spp.).
Brush mice have been observed caching pinyon pine seeds. This observation suggests that the brush mouse may play a role in seed dispersal for some plant species.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the family Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
. It is found in mountainous areas of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
and the western United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
at altitudes over 2000 metres (6,561.7 ft).
Description
The brush mouse is a medium-sized mouse with small ears and a long tail. It has yellowish-brown fur on the body, with slate grey underparts. The tail has only sparse hair for most of its length, but a distinct brush-like tuft of hair at the tip (although the common name is, perhaps, more likely to come from brushy environment in which it lives). It has a head-body length of 86 to 105 mm (3.4 to 4.1 in) with a tail 88 to 115 mm (3.5 to 4.5 in) long. It is very similar in appearance to a number of closely related species of mouse living in the same area, although it can be distinguished from them by such features as the length of its tail, the size of its ears, and the presence of the tuft on the end of the tail.Distribution and habitat
The brush mouse can be found from northern California, to eastern Colorado and western Texas, and south to Baja California and southern Mexico. Fossils of brush mice up to 35,000 years old have been discovered, but none have been definitively identified from outside the current range of the speciesVegetation in brush mouse habitats may vary from location to location, but brush mice are consistently captured in areas with medium to high densities of shrubs and tree cover under 16 feet (5 m) in height. In California, mature chaparral (cover ≥50%) appears to provide more suitable habitat for brush mice than young, open chaparral (cover <50%). Similarly, in Arizona, Duran captured brush mice most frequently in shrub live oak and birchleaf mountain-mahogany (Cercocarpus betuloides) understory habitats with 45% to 50% plant cover. Fewer brush mice were captured in habitats with less plant cover. Holbrook observed that after vegetation crowns were removed in a manzanita (Arctostaphylos spp.)-oak shrubland, brush mice avoided the newly-opened space. In another study, brush mice were strongly restricted to habitats in which gaps between rocks or ceanothus (Ceanothus spp.) on the site were less than 4 feet (1.2 m).
In addition to shrub density, the height of cover appears to influence brush mouse distribution within a site. An average understory height of 5–6.5 feet (1.5–2.0 m) was preferred by brush mice over lower understory cover. In another study, brush mouse presence was positively correlated with microhabitats of shrub cover up to 10 feet (3 m) tall, logs over 3 inches (7.5 cm) in diameter, and understory trees 10–33 feet (3–10 m) in height, but negatively correlated with grass-forb microhabitats.
Brush mice are also commonly captured at locations with a high proportion of rock cover and/or slash piles in habitats characterized by chaparral-mountain shrub, oak/shrub, oak-juniper-pinyon pine, juniper-pinyon pine, and oak-pine communities, as well as riparian habitats. The brush mouse in Texas has been found in all major habitats present (desert, grassland, riparian, and montane) although it is typically associated with rock outcrops within these habitats. Riparian sites with abundant brush mouse populations had high shrub cover, high frequency of debris piles with low grass, litter, and tree cover. In a Mexico study, a canyon was dominated by exposed rock, grasses, pines, hardwoods, and brush. In western Texas, brush mice favored fallen logs and brush piles. Modi discovered that brush mice were common in riparian zones dominated by pecan (Carya illinoensis), American sycamore (Platanus occidentalis) and live oak (Quercus virginiana), in an oak community with a partially open canopy and dense understory, and in a pine forest with little understory and scattered boulders. In New Mexico, brush mouse populations were significantly higher (P<0.05) on sites that were bulldozed or thinned (98 and 115 captures, respectively) than untreated or bulldozed and burned sites. Populations were lowest on sites that had not been treated (45 captures). Sites that had increased slash from bulldozing and burning had more brush mice (57 captures) than the untreated sites, but the difference was not significant (P>0.05). No influence of canopy cover on brush mice was observed in the study.
Besides high tree, shrub, and rock densities, brush mice appear to prefer locations with low grass cover. At the same time, grasses are often present in the understory indicating that grasses do not exclude brush mice. Brush mice utilized grazed and ungrazed pastures and ceanothus plots, but they were concentrated around rocky outcrops and vegetation continuous with the rock outcrops. No brush mice were captured in the grasslands more than 20 feet (6 m) from rocks, shrubs, or trees. Litter depth also appears negatively correlated to brush mouse presence. For instance, brush mice in Arizona were captured in litter depths of only 0.9 inches (2.4 cm).
Brush mice also utilize fire-affected habitats. In one study, brush mice were captured in burned and unburned chaparral as well as burned and unburned pine-oak forest. The highest number of captures were recorded in unburned forest while the lowest captures occurred in the unburned chaparral. These results are somewhat inconsistent with other observations which show the brush mouse favoring dense chaparral habitat. Small mammal capture data in the study were collected from 14 months to 3 years after fire. The time frame of sampling after fire may influence the perceived response of the brush mouse to postfire habitats.
Elevation, in addition to habitat characteristics, may play a role in habitat suitability in some areas. For instance, in the northern Sierra Nevada of California, brush mice were captured in brush habitats at 3,500–5,000 feet (1,000–1,500 m), but not at 6,500 feet (2,000 m). Aspect may influence the distribution of brush mice on a site as well. For example, in New Mexico, 51% of all brush mice captured were taken on south-facing slopes, 24% on west-facing slopes, with 13% and 12% of mice captured on east- and north-facing slopes, respectively. The south-facing canyon slopes may provide more cover for brush mice due to higher numbers of shrubs.
Although brush mice are found on a variety of slopes, including flat mesas and gradual slopes, they seem to prefer locations with very steep slopes, such as hillsides, mountain sides, and canyons (including some slopes with >45% gradient) over more gradual slopes in the same areas. Findley reported that brush mice were captured on hillsides in an oak/sacahuista (Nolina spp.) community. In another study, brush mice were common in canyon bottoms, on hillsides, and in arroyos (water channels in arid regions) characterized by oak woodlands. Brush mice have also been captured along the sides of brush covered canyons and burned slopes of an oak/brush association.
Subspecies
Four subspecies of brush mouse are currently identified:- Peromyscus boylii boylii - northern California
- Peromyscus boylii glasselli - San Pedro Nolasco IslandSan Pedro Nolasco IslandSan Pedro Nolasco Island, sometimes called Seal Island, is a small and rugged Mexican island in the Gulf of California. It is 4.2 km long by 1 km wide, and lies 15 km from the nearest point of the Mexican coast and about 28 km west of the resort town of San Carlos on the coast of the Sonoran Desert...
- Peromyscus boylii rowleyi - remainder of range
- Peromyscus boylii utahensis - central Utah
Density and home range
Kalcounis-Ruppell discovered brush mouse population densities were 40–72 mice per hectare in coastal California. Similarly, Kalcounis-Ruppell and Millar determined that densities of brush mice in coastal California were 42–89 mice per hectare. Brush mouse densities appear greatly influenced by weather. Densities were 17–20 per acre one year, but were reduced to 6 mice per acre following a severe winter. At another study site, brush mice increased from 4 individuals per acre to 12 per acre after a mild winter. Populations in a canyon in Mexico were estimated at a mean of 10.8 brush mice per acre or 6.0 males and 4.8 females per acre. The range was 9–14 brush mice per acre.A study utilizing radiotelemetry and trapping data in Arizona estimated mean home range size for male brush mice at 0.72–1.6 acres (0.29–0.64 hectare), and 0.32–0.79 acre (0.13–0.32 hectare) for females. In another study at the same location, home ranges for male brush mice ranged from means of 1.2–1.5 acres (0.47–0.62 hectare) and for females, means of 0.64–1.2 acres (0.26–0.49 hectare). Mean home range for male and female brush mice in Arizona, based on radiotelemetry, was 0.30 acre (0.12 hectare).
Cover requirements
No significant differences in habitat use between genders were observed in Arizona. Typical brush mouse habitat in southern Arizona was characterized by 74% tree cover, 60% leaf cover, 21% shrub cover, and 16% rock cover. Additionally, 67% of all brush mice relocated by radiotelemetry in the study were located in a riparian zone with the other observations occurring in uplands and an intermittent stream channel. Brush mice used sites with significantly (P<0.05) more rock cover (19% to 22%) during winter and spring than at other times of the year. Also in spring, plots with the most brush mice also had significantly (P<0.05) more shrub cover (21% vs.14%) and succulents (9% vs. 2%) than random plots.In a New Mexico study, 27% of brush mice captured were taken around rocky areas, 10% under Gambel oak (Q. gambelii), 9% under juniper, and 7% each around woodpiles and sacahuista. Less frequently, brush mice were taken under or around pinyon pine, gray oak (Q. grisea), Apache plume, rabbitbrush, mountain-mahogany, white fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii), locust (Robinia spp.), prickly-pear, cholla (Opuntia spp.), chokecherry (Prunus spp.), bricklebush (Brickellia spp.), and grape (Vitis spp.).
In southern California, brush mice were captured on leaf mold in an oak hardwood association of coast live oak, white alder (Alnus rhombifolia), whiteflower currant, and sumac (Rhus spp.). They were also trapped under logs and dense vegetation and on wet seepage slopes next to a creek. In coastal California, brush mice were captured primarily under coast live oak, false-willow (Baccharis douglasii), California buckeye, and California bay.
Fallen logs and rock outcrops provide nest sites for the brush mouse. They may also construct nests in tree hollows and underground burrows. Brush mice living in mine shafts or caves build nests similar to those of goldfinches. Davis noted that the brush mouse nest is a "globular structure" and is constructed primarily of dried grasses within natural cavities. Brush mouse nest sites in California were found on sites with a high density coast live oak (Q. agrifolia) overstory and an open understory with low vegetation and ground cover.
California
In California, overstory associates include gray pine (Pinus sabiniana) and California buckeye (Aesculus californicaAesculus californica
Aesculus californica is a species of buckeye that is native [ |] to California and southwest Oregon [Jackson, County], and the only buckeye native to these states.-Description:...
). Understory and other herbaceous species include bulrushes (Scirpus
Scirpus
The plant genus Scirpus consists of a large number of aquatic, grass-like species in the family Cyperaceae , many with the common names club-rush or bulrush . Other common names are deergrass or grassweed.The genus has a cosmopolitan distribution, and grows in wetlands and moist soil...
spp.), fourwing saltbrush (Atriplex canescens
Atriplex canescens
Atriplex canescens, Chamiso, Chamiza, Four wing saltbush, Four-wing saltbush, and Fourwing saltbush, is a species of evergreen shrub in the Amaranthaceae family, which is native to the western and mid-western United States....
), and rubber rabbitbrush (Chrysothamnus nauseosus
Chrysothamnus nauseosus
Ericameria nauseosa , commonly known as Chamisa, rubber rabbitbrush, and gray rabbitbrush, is a shrub of the genus Ericameria that grows in the arid regions of western North America. Two subspecies have been described, nauseosa and consimilis...
). Whiteflower currant (Ribes indecorum
Ribes indecorum
Ribes indecorum is a species of currant known by the common name white-flowered currant. It is native to the Coast Ranges of California from around Santa Barbara County south into northern Baja California, where it grows in local habitat such as chaparral and coastal sage scrub.It is an erect shrub...
), California bay (Umbellularia californica), black sage (Salvia mellifera), laurel sumac (Malosma laurina), and deerweed (Lotus scoparius
Lotus scoparius
Lotus scoparius is a perennial subshrub in the family Fabaceae . The plant is a pioneer species found in dry areas of California, Arizona, and Mexico...
) may also be present. Understories may also include exotic annual forbs and grasses such as mustard (Brassica spp.), oats (Avena spp.), and brome (Bromus spp.).
Arizona
In Arizona, overstories where brush mice are found are characterized by desert willow (Chilopsis linearis), Arizona sycamore (Platanus wrightiiPlatanus wrightii
Platanus wrightii , is a sycamore tree native to Arizona and New Mexico with its range extending south into Sonora, and a small area of Chihuahua Mexico....
), and shrub live oak (Quercus turbinella
Quercus turbinella
Quercus turbinella is a species of oak known by the common names Sonoran scrub oak and shrub live oak. It is native to northwestern Mexico and the southwestern United States from far eastern California to southwest Colorado, Rio Grande New Mexico, to west Texas.-Distribution:Quercus turbinella...
). Shrub associates include evergreen sumac (Rhus virens), skunkbush sumac (Rhus trilobata
Rhus trilobata
Rhus trilobata is a shrub in the sumac genus with the common names sourberry, skunkbush, and three-leaf sumac. It is native to the western half of Canada and the Western United States, from the Great Plains to California and south through Arizona extending into northern Mexico...
), roundleaf snowberry (Symphoricarpos rotundifolius
Symphoricarpos rotundifolius
Symphoricarpos rotundifolius is a species of flowering plant in the honeysuckle family known by the common name roundleaf snowberry. It is native to the western United States from California to Idaho to Texas, where it grows in many types of habitat. It is an erect, spreading, or trailing shrub...
), New Mexico locust (Robinia neomexicana), common hoptree (Ptelea trifoliata), fendlerbush (Fendlera
Fendlera
Fendlera is a genus of shrubs in the Hydrangeaceae. They are most commonly known as fendlerbush. The name fendlerbush is also used for the closely related genus Fendlerella....
rupicola), Carruth's sagewort (Artemisia carruthii), catclaw acacia (Acacia greggii
Acacia greggii
Acacia greggii is a species of Acacia native to the southwestern United States and northern Mexico, from the extreme south of Utah south through southern Nevada, southeast California, Arizona, New Mexico and western Texas to Baja California, Sinaloa and Nuevo León in...
), broom snakeweed (Gutierrezia sarothrae
Gutierrezia sarothrae
Gutierrezia sarothrae is a species of flowering plant in the daisy family known by the common names broom snakeweed and perennial matchweed. It is native to much of the western half of North America, from central Canada to northern Mexico...
), red barberry (Mahonia haematocarpa
Mahonia haematocarpa
Mahonia haematocarpa is a species of barberry known by the common name red barberry. It is also sometimes called algerita, but that name is more often applied to its relative, Mahonia trifoliolata...
), netleaf hackberry (Celtis reticulata
Celtis reticulata
Celtis reticulata, with common names including Netleaf Hackberry, Western Hackberry, Douglas Hackberry, Netleaf Sugar Hackberry, Palo Blanco, Acibuche, is a small to medium size deciduous tree, native to western North America.-Prehistoric:Celtis reticulata was one of the species analyzed in a...
), and wait-a-minute (Mimosa
Mimosa
Mimosa is a genus of about 400 species of herbs and shrubs, in the subfamily Mimosoideae of the legume family Fabaceae. The generic name is derived from the Greek word μιμος , meaning "mimic."...
aculeaticarpa var. biuncifera). Herbaceous and succulent species in brush mouse habitats include Wheeler sotol (Dasylirion wheeleri
Dasylirion wheeleri
Dasylirion wheeleri is a flowering plant native to arid environments of northern Mexico, in Chihuahua and Sonora and in the southwestern United States, in the Sonoran Desert in Arizona, and also in New Mexico and Texas.-Description:Dasylirion wheeleri is a moderate to slow-growing evergreen shrub...
), sacahuista (Nolina
Nolina
Nolina is a genus of tropical xerophytic flowering plants, with the principal distribution being in Mexico and extending into the southern United States. Some botanists have included the genus Beaucarnea in Nolina. In the APG III classification system, it is placed in the family Asparagaceae,...
microcarpa), Palmer agave (Agave
Agave
Agave is a genus of monocots. The plants are perennial, but each rosette flowers once and then dies ; they are commonly known as the century plant....
palmeri), goldenrod (Solidago spp.), lupine (Lupinus spp.), prickly-pear (Opuntia
Opuntia
Opuntia, also known as nopales or paddle cactus , is a genus in the cactus family, Cactaceae.Currently, only prickly pears are included in this genus of about 200 species distributed throughout most of the Americas. Chollas are now separated into the genus Cylindropuntia, which some still consider...
spp.), and ocotillo (Fouquieria splendens). Grasses found in brush mouse habitat include Lehmann lovegrass (Eragrostis lehmanniana), bottlebrush squirreltail (Elymus elymoides
Elymus elymoides
Elymus elymoides is a species of wild rye known by the common name squirreltail. This grass is native to most of North America west of the Mississippi River. It occurs in a number of ecosystems, from alpine forest to desert sage scrub to valley grassland.-Description:Elymus elymoides is a perennial...
), and other annual and perennial bunchgrasses.
New Mexico
New Mexico habitats are characterized by rabbitbrush (ChrysothamnusChrysothamnus
Chrysothamnus is a member of the plant family Asteraceae. It is a semi-deciduous shrub, sometimes also called sagebrush. The native distribution is in the arid western United States and northern Mexico...
spp.), Apache plume (Fallugia paradoxa), fourwing saltbrush, common hoptree and crispleaf buckwheat (Eriogonum
Eriogonum
Eriogonum is the scientific name for a genus of flowering plants, in the family Polygonaceae. The genus is found in North America and is known as wild buckwheat. This is a highly species-rich genus, and indications are that active speciation is continuing...
corymbosum) in addition to a pinyon-juniper-mountain-mahogany (Pinus
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
-Juniperus-Cercocarpus spp.) overstory. Texas plant associates include Pinchot juniper (Juniperus pinchotii
Juniperus pinchotii
Juniperus pinchotii is a species of juniper native to southwestern North America, in Mexico: Nuevo León and Coahuila, and in the United States: southeast New Mexico, central Texas, and western Oklahoma.It grows at 600–2,100 m altitude.-Description:Juniperus pinchotii...
), algerita (Mahonia trifoliolata
Mahonia trifoliolata
Mahonia trifoliolata is a species of flowering plant in the family Berberidaceae that is native to Texas, New Mexico, and Arizona in the United States and northern Mexico. Common names include Agarita, Agrito, Algerita, Currant-of-Texas, Wild Currant, and Chaparral Berry...
), clapweed (Ephedra
Ephedra
Ephedra refers to the plant Ephedra sinica. E. sinica, known in Chinese as ma huang , has been used in traditional Chinese medicine for 5,000 years for the treatment of asthma and hay fever, as well as for the common cold...
antisyphilitica), featherplume (Dalea
Dalea
Dalea is a genus of flowering plants in the pea family, Fabaceae. Members of the genus are commonly known as prairie clover or indigo bush. Its name honours English apothecary Samuel Dale .-Species:-Formerly placed here:...
formosa), and prickly-pear (Opuntia
Opuntia
Opuntia, also known as nopales or paddle cactus , is a genus in the cactus family, Cactaceae.Currently, only prickly pears are included in this genus of about 200 species distributed throughout most of the Americas. Chollas are now separated into the genus Cylindropuntia, which some still consider...
spp.).
Timing of major life events
Brush mice are nocturnal. Brush mice appear to limit activity during cooler months in the Sierra Nevada of California, although they are not known to hibernate or enter torpor. In southern areas, such as Arizona, Texas, and northern Mexico, brush mice are active year-round.Brown reported that brush mice reach sexual maturity at 12–19 weeks. However, Clark reported that female brush mice may reach sexual maturity in approximately 5–9 weeks. In Arizona, females born in late May or June were found pregnant during August of the same year. In western Texas, Arizona, southern Utah, and Mexico, breeding appears to occur nearly year-round. However, in northern California, Jameson found that breeding in brush mice peaked twice each year, once in late spring and again in late summer. This result may be related to food availability.
Female brush mice carry 1–6 embryos each with an average of 3–4 embryos. Lactating females may become pregnant, although lactation may slow the development of embryos in Peromyscus species. Bradley and Schmidly reported that the gestation period of the brush mouse is around 23 days. Females may have multiple litters per year. The amount of time between litters is likely similar to other Peromyscus species and may be 25–31 days. Young are weaned at 3–4 weeks of age.
Brush mice have a promiscuous mating system. Four out of 7 litters in a California study were fathered by several males. Males and females did not share nests and mating pairs did not remain together for long periods of time.
Few Peromyscus spp. mice live longer than 6 months in the wild, but individuals may live up to 4–5 years in captivity.
Food habits
Brush mice are semiarboreal and can be found foraging in shrubs and trees for leaves and fruits. Females were captured more often than males foraging in canyon live oaks (Q. chrysolepis) (P<0.05). The individuals with the longest tails appear to spend more time climbing than those with shorter tails.Acorns are commonly eaten by brush mice wherever they are available. Arthropods and cutworms (Protorthodes rufula) are also eaten throughout the year. A variety of fruits and seeds from Douglas-fir, ponderosa pine (Pinus ponderosa), pinyon, California buckeye, manzanita (A. patula and A. viscida), silktassel (Garrya spp.), oneseed juniper (Juniperus monosperma), hackberries (Celtis spp.), New Mexico groundsel (Senecio neomexicanus var. neomexicanus), trailing fleabane (Erigeron flagellaris), annual sunflower (Helianthus annuus), broom snakeweed, common dandelion (Taraxacum officinale), western yarrow (Achillea millefolium), white sweetclover (Melilotus albus), threenerve goldenrod (Solidago velutina), prickly-pear, desert wheatgrass (Agropyron desertorum), Kentucky bluegrass (Poa pratensis), and blue grama (Bouteloua gracilis) are eaten throughout the year when available. Other plant parts, such as leaves, stems, flowers, pollen cones and new sprouts are typically eaten in lower quantities than other foods. Fungi are typically consumed when other foods are scarce. Infrequently, stomach contents of brush mice contained pieces of mammals, birds, and fence lizards (Sceloporus spp.).
Brush mice have been observed caching pinyon pine seeds. This observation suggests that the brush mouse may play a role in seed dispersal for some plant species.
Predators
Predators of the brush mouse include birds of prey such as the northern goshawk (Accipiter gentilis) and spotted owl (Strix occidentalis). Potential mammalian predators of the brush mouse may include the coyote (Canis latrans), common gray fox (Urocyon cinereoargenteus), red fox (Vulpes vulpes), swift fox (Vulpes velox), ringtail (Bassariscus astutus), American marten (Martes americana), fisher (Martes pennanti), ermine (Mustela erminea), long-tailed weasel (Mustela frenata), striped skunk (Mephitis mephitis), hooded skunk (Mephitis macroura), white-backed hog-nosed skunk (Conepatus leuconotus), northern raccoon (Procyon lotor), bobcat (Lynx rufus), and ocelot (Leopardus pardalis). Snakes also prey on brush mice.Further reading
- Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 in Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore.