Peromyscus fraterculus (Northern Baja deermouse)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Habitat List
- Biology and Ecology
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Vectors
- Impact Summary
- Environmental Impact
- Threatened Species
- Social Impact
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Peromyscus fraterculus Miller
Preferred Common Name
- Northern Baja deermouse
Other Scientific Names
- Peromyscus eremicus propinquus J.A. Allen
- Peromyscus homochroia Elliot
- Sitomys herroni Rhoads
- Sitomys herroni nigellus Rhoads
- Vesperimus fraterculus Miller
Summary of InvasivenessTop of page
P. fraterculus is a common peninsular rodent species that is native to southwest California, USA, and the Baja California Peninsula, Mexico (Musser and Carleton, 2005). In the early 1990’s, P. fraterculus was introduced to the Isla Santa Catalina, Sea of Cortez, Mexico, where it is competing with the critically endangered endemic species Peromyscus slevini (Alvarez-Castañeda et al., 2009).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Mammalia
- Order: Rodentia
- Family: Muridae
- Subfamily: Hesperomyinae
- Genus: Peromyscus
- Species: Peromyscus fraterculus
Notes on Taxonomy and NomenclatureTop of page
Peromyscus fraterculus was originally described by Miller in The American Naturalist in 1892. Following revisions of the genus by Osgood (1904; 1909), it was long considered a geographic race of P. eremicus. However, studies of allozymic and DNA variation within P. eremicus as conceived by Osgood suggested that western and eastern moieties were specifically distinct (Musser and Carleton, 2005). Riddle et al. (2000) confirmed the pronounced genetic divergence, which further supported P. fraterculus as a distinct species. Riddle et al. (2000) interpreted P. fraterculus origination in a phylogeographic context and suggested that its divergence from P. eva (the Southern Baja Deermouse) probably occurred in the late Neogene.
DescriptionTop of page
Adult male and female P. fraterculus weigh about 24 grams (range 18 to 40 grams), and are about 169-218 mm in length. They are medium-sized deer mice with ears and long tails, and long soft fur.
DistributionTop of page
The geographic range of P. fraterculus includes southwest California, USA, south into central Baja California Sur, Mexico (Musser and Carleton, 2005). Within this geographic range the species is considered native and common, however, its current population trend is unknown (Ceballos and Oliva, 2005). The species also occurs on several islands in the Gulf of California (Alvarez-Castañeda et al., 2009; Vazquez et al., 2014). The IUCN lists the species as Least Concern in view of its wide distribution (Timm et al., 2008). Alvarez-Castañeda et al. (2010) point out that the reported distribution of the species has changed several times, partly due to morphological similarity with other Peromyscus species. After genetic analysis, Alvarez-Castaneda et al. (2010) report the distribution of P. fraterculus as “in mountains in the Baja California Peninsula from the northern part of Baja California to the southeastern part of Baja California Sur”.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Mexico||Present||Native||Musser and Carleton, 2005; Alvarez-Castaneda et al., 2009; Alvarez-Castaneda et al., 2010||Baja California Peninsula|
|USA||Present||Present based on regional distribution.|
|-California||Present||Native||Not invasive||Musser and Carleton, 2005; Timm et al., 2008||Southern coastal areas|
History of Introduction and SpreadTop of page
In the early 1990’s, accidental dissemination, possibly by fishermen, may have brought P. fraterculus to Isla Santa Catalina, Mexico (Alvarez-Castañeda and Cortes, 2002). This is a small (41-km2) uninhabited oceanic island in the southern Sea of Cortez (Gulf of California), Mexico. Isla Santa Catalina is situated 27 km northeast of Punta San Marcial on the Baja California Peninsula (Carreno and Helenes, 2002). Collections on Isla Santa Catalina made in 1992 identified only P. slevini, while in October 1995 specimens of P. fraterculus were captured (Hafner et al. 2001). Field research conducted by Alvarez-Castañeda et al. (2009) documented the invasion of P. fraterculus and reported that its on-going population expansion is restricting P. slevini to the canyons and inland areas of the island.
HabitatTop of page
P. fraterculus is found in areas of desert shrub land and rocky slopes. P. fraterculus will live in burrows when the soil is sandy; but, also lives in piles of vegetation and rocky crevices when the soil is hard or rocky (Timm et al., 2008). Where its range overlaps with that of P. eva, the species occupy different microhabitats, with P. fraterculus mostly present on hard soils with high content of medium-sized stones, and P. eva in areas with friable and soft sandy soil and few stones (Alvarez-Castaneda et al., 2010). P. fraterculus is most often found in mountains and canyons (Alvarez-Castañeda et al., 2010).
In its introduced range on the Isla Santa Catalina, P. fraterculus is found in the coastal and open areas on the island (Alvarez-Castañeda et al., 2009).
Habitat ListTop of page
|Terrestrial ‑ Natural / Semi-natural||Rocky areas / lava flows||Principal habitat||Natural|
|Scrub / shrublands||Principal habitat||Natural|
|Coastal areas||Principal habitat||Natural|
Biology and EcologyTop of page
Physiology, Longevity and Activity Patterns
P. fraterculus exhibits nocturnal behavior and can enter into extended states of inactivity during the summer months which allows it to cope with arid conditions (Caire, 1999; Timm et al., 2008). The diet of P. fraterculus varies with seasonal availability, but may include seeds, insects, flowers and fruit (Timm et al., 2008). The average life span is probably one year (Timm et al., 2008; Smithsonian National Museum of Natural History, 2016).
Females may have three to four litters in a year, with one to four offspring in each litter. Young are usually independent before they are two weeks old (Timm et al., 2008; Smithsonian National Museum of Natural History, 2016).
ClimateTop of page
|BS - Steppe climate||Preferred||> 430mm and < 860mm annual precipitation|
|BW - Desert climate||Preferred||< 430mm annual precipitation|
Notes on Natural EnemiesTop of page
Peromyscus species are popular prey for many reptiles, birds, and predatory mammals; no specific information for P. fraterculus or P. slevini was found.
Means of Movement and DispersalTop of page
Accidental dissemination, possibly by fishermen, may have caused the invasion of P. fraterculus to Isla Santa Catalina (Alvarez-Castaneda and Cortes, 2002).
Hafner et al. (2001) suggest that overwater dispersal could potentially be a natural means for P. fraterculus to have arrived on Isla Santa Catalina, but Alvarez-Castañeda (personal communication) believes that this is unlikely.
Pathway VectorsTop of page
Impact SummaryTop of page
Environmental ImpactTop of page
The Isla Santa Catalina in the Sea of Cortez (Gulf of California, Mexico) has only one endemic mammal - the Catalina deermouse, Peromyscus slevini (Musser and Carleton, 2005). From 1990 through 2007, field surveys conducted by different researchers showed that the invasion of P. fraterculus is changing the composition and distribution of the mammal species. P. fraterculus is the better desert adapted species and its expansion is restricting P. slevini to the canyons, and competition between P. fraterculus and P. slevini could lead to the extinction of P. slevini (Alvarez-Castañeda et al., 2009).
P. slevini is already considered endangered by the Government of Mexico (Alvarez-Castaneda et al., 2009), and Critically Endangered by the IUCN (Alvarez-Castañeda and Castro-Arellano, 2008).
A suite of biotic and abiotic factors affect the ability of an invasive species to cause the decline of a native species (Donlan and Wilcox, 2008). Island size, carrying-capacity, and habitat specialization are contributing factors that may enhance the ability of P. fraterculus to outcompete P. slevini, resulting in the loss of biodiversity at the species and community levels. Invasions are known to trigger the decline or extinction of a species, particularly in island ecosystems (Donlan and Wilcox, 2008).
Threatened SpeciesTop of page
Social ImpactTop of page
In the western USA, the flea Oropsylla montana is the primary plague vector for the hantavirus (Lang, 1993). From 1991 to 1992, vector-borne disease surveillance studies in San Diego County, California, collected flea species from numerous host taxa. Well-represented hosts with flea species included P. eremicus fraterculus (Lang, 1993). The Centers for Disease Control and Prevention (2012) recommends avoiding close contact with rodents to prevent acquiring the hantavirus.
Risk and Impact FactorsTop of page Invasiveness
- Invasive in its native range
- Abundant in its native range
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Competition - monopolizing resources
- Difficult to identify/detect in the field
Similarities to Other Species/ConditionsTop of page
P. fraterculus is morphologically similar to other species of the P. eremicus group, e.g. P. eva. The similarity of these species has resulted in confusion about their habitat characteristics and geographic ranges (Alvarez-Castañeda et al., 2010). Differences between the species include P. eva having a longer tail, shorter and more reddish fur, and smaller ears than P. fraterculus (Osgood, 1909). Differing characteristics of the phallus are also key to distinguishing between the two species (Alvarez-Castañeda et al., 2010), including a smaller size and a small cartilaginous tip in P. eva.
Several scientists conducted field studies on Isla Santa Catalina between 1993 and 2007. Survey methodology included the collection of rodent specimens and use of morphological differences to tentatively determine the species of Peromyscus. The surveys initially identified the trapped specimens as P. fraterculus but two morphotypes of the species were noted, with the larger sized specimens collected in the latest surveys of 2006-2007 tentatively identified as P. slevini (Alvarez-Castañeda et al., 2009). Carleton and Lawlor (2005) queried the finding only of P. slevini in collections made in January 1992, and of only P. fraterculus in October 1995, suggesting that three years would be too short a time for interference competition to cause one species to ecologically supplant the other, and suggested that field confirmation of the species composition of Peromyscus populations on the island was needed.
There are also taxonomic and morphological concerns regarding P. slevini and whether it is a distinct species (Caire, 1999; Musser and Carleton, 2005). In 2001, genetic research by Hafner et al. suggested the possibility of P. slevini as a synonym of P. fraterculus. However, the specimens used by Hafner are now considered to be examples of P. fraterculus and not P. slevini as described by Mailliard in 1924 (Caire, 1999; Musser and Carleton, 2005).
Following Mailliard’s original species description other scientists have offered subsequent contradictory interpretations of the taxonomic classification of P. slevini to the subgenus or species (Carleton and Lawlor, 2005). Carleton and Lawlor (2005) noted that the cranium of P. slevini has certain characteristics that are similar to other Peromyscus found on the Mexican mainland, specifically P. melanophrys. Genetic research by Hogan et al. (1997) questioned whether P. slevini was an outgroup relative to the P. leucopus-P. maniculatus species groups. The specimens used by Hogan are now recognized as explicitly P. slevini.
Additional field studies and genetic evaluations are warranted due to the persistent contradictions regarding the taxonomic classifications of P. fraterculus and P. slevini, and the intra and inter-hybrid fertility in Peromyscus resulting in morphological characteristics and chromosome complexes (Cross, 1938). The outcomes of such investigations will assist in definitively describing the status and relationships of P. fraterculus and P. slevini on the Isla Santa Catalina, Mexico (Caire, 1999; Carleton and Lawlor, 2005; Musser and Carleton, 2005).
Prevention and ControlTop of page
Detection and Inspection Methods
Alvarez-Castañeda et al. (2009) trapped and identified P. fraterculus using morphological characteristics. Alvarez-Castañeda et al. (2010), when comparing the distribution of P. fraterculus with that of P. eva, suggested that the usefulness of differing morphologies was limited by availability of relevant structures, and developed a genetic test to distinguish between the species.
Trap and kill is used to control rodent populations, but care would need to be taken to identify and release P. slevini.
ReferencesTop of page
Alvarez-Castaneda ST; Arnaud G; Cortes-Calva P; Mendez L, 2009. Invasive migration of a mainland rodent to Santa Catalina Island and its effect on the endemic species Peromyscus slevini. Biological Invasions, 12:437-439.
Âlvarez-Castañeda ST; Castro-Arellano I, 2008. Peromyscus slevini. The IUCN Red List of Threatened Species, e.T16690A6291614.
Alvarez-Castaneda ST; Cortes-Calva P, 2002. Peromyscus slevini. Mammalian Species, 705:1-2.
Alvarez-Castaneda ST; Cortes-Calva P; Gonzalez-Cozati FX; Rojas D; Leyva I, 2010. Comparison of distribution and habitat characteristics between and endemic and wide-ranging cryptic species of Peromyscus on the Baja California Peninsula. Western North American Naturalist, 70(3):323-333.
Caire W, 1999. Cactus Mouse. In: Mammal Species of the World: a geographic and taxonomic reference [ed. by Wilson, D. E. \Reeder, D. A.]. Baltimore, USA: The John Hopkins University Press.
Carlton MD; Lawlor TE, 2005. Peromyscus from Santa Catalina Island, Sea of Cortez, Mexico: Taxonomic identities and biogeographic locations. Journal of Mammalogy, 86(4):814-825.
Carreno AL; Helenes J, 2002. Geology and ages of the islands. In: A new island biogeography of the Sea of Cortes [ed. by Case, T. J. \Cody, M. L. \Ezcurra, E.]. Oxford, UK: Oxford University Press, 14-40.
Ceballos G; Oliva G, 2005. Los mamíferos silvestres de México ([English title not available])., Mexico: Comisión Nacional para el Conocimiento y Uso de la Biodiversidad and Fondo de Cultura Económica.
Centers for Disease Control and Prevention, 2012. Rodents in the United States that Carry Hantavirus. www.cdc.gov/hantavirus/rodents/
Hafner DJ; Riddle BR; Alvarez-Castaneda ST, 2001. Evolutionary relationships of white-footed mice (Peromyscus) on islands in the Sea of Cortez, Mexico. Journal of Mammalogy, 82(3):775-790.
Hogan KM; Davis SK; Greenbaum IF, 1997. Mitochondrial-DNA analysis of the systematic relationships within the Peromyscus maniculatus species group. Journal of Mammalogy, 78:733-743.
Musser GG; Carleton MD, 2005. Superfamily Muroidea. In: Mammal Species of the World: A taxonomic and geographic Reference, 3rd ed., vol 2 [ed. by Wilson, D. E. \Reeder, D. M.]. Baltimore, Maryland, USA: John Hopkins University Press.
Osgood WH, 1904. Haplomylomys, a new subgenus of Peromyscus. North American Fauna, 18:1-72.
Osgood WH, 1909. Revision of mice of the American genus Peromyscus. North American Fauna, 28:1-285.
Riddle BR; Hafner DJ; Alexander LF, 2000. Phylogeography and systematics of Peromyscus eremicus species group and the historical biogeography of North American warm regional deserts. Molecular Phylogenetics and Evolution, 17(2):145-160.
Smithsonian National Museum of Natural History, 2016. North American Mammals. http://naturalhistory.si.edu/mna/search_name.cfm
Suárez-Gracida CG; Álvarez-Castañeda ST, 2009. Physical and biological variables related to habitat preferences of rodents. Biodiversity and Conservation, 18(11):2779-2797. http://www.springerlink.com/content/6k80180671181682/fulltext.html
Timm R; Alvarez-Cataneda ST; Lacher T, 2008. Peromyscus fraterculus. The IUCN Red List of Threatened Species, e.T136412A4288340.
Vázquez J; Álvarez-Castañeda ST, 2014. Influence of kangaroo rat burrows in the spatial organization of the San Jose Island rodent community. Journal of Arid Environments, 111:84-90. http://www.sciencedirect.com/science/article/pii/S0140196314001748
ContributorsTop of page
20/05/16 Original text by:
Kristen Nelson, Consultant, USA
Distribution MapsTop of page
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