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Overview

Brief Summary

Description

The Arizona Shrew was at first found only in Arizona, but it is now known to occur in New Mexico and northern Mexico as well. Until the 1990s, only about 22 specimens had ever been collected. Recent efforts to locate this shrew have paid off, though not much more is known about its habits. Like other shrews, the Arizona Shrew appears to be active at nearly every hour, with periods of rest between hunting and feeding excursions. The small stomach on this tiny mammal is not large enough to hold much surplus food, and that, in combination with a heightened metabolism, pushes the animal to nearly constant feeding activity. These shrews require a thick canopy of vegetation, and have been found on forested slopes at elevations between 1,575 m and 2,590 m.

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Mammal Species of the World
  • Original description: Diersing, V. A., and D. F. Hoffmeister, 1977. Revision of the shrew Sorex merriami and a description of a new species of the subgenus Sorex, p. 329.  Journal of Mammalogy, 58:321-333.
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Distribution

occurs (regularly, as a native taxon) in multiple nations

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (5000-200,000 square km (about 2000-80,000 square miles)) The range includes portions of the southwestern United States and northern Mexico; the species is presently known only from the Huachuca, Santa Rita, and Chiricahua mountains of southeastern Arizona, the Animas mountains of southwestern New Mexico, and the Sierra Madre Occidental of Chihuahua, Mexico (Caire et al. 1978, Junge and Hoffman 1981, Simons and Hoffmeister 2003). Elevational records range from 1,575 to 2,590 meters (Simons and Hoffmeister 2003).

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Range Description

This species' distribution is restricted to southeastern Arizona, southwestern New Mexico, in the United States, and northwestern Mexico (Nowak, 1999) in the state of Chihuahua. It is found from 1,500 to 2,600 m asl (Wilson and Ruff, 1999). The only known Mexican specimen was collected at 2,591 m asl.
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Physical Description

Size

Length: 11 cm

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Size in North America

Sexual Dimorphism: None

Length:
Average: 101 mm
Range: 79-114 mm

Weight:
Average: 3.3 g
Range: 1.9-5.2 g
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Diagnostic Description

See Carraway (1995) for a key to western North American soricids based primarily on dentaries.

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Ecology

Habitat

Comments: This shrew nearly always is found beneath a thick canopy of vegetation (Simons, in Wilson and Ruff 1999). It has been collected in montane conifer forest and encinal and Mexican oak-pine woodland, in relatively mature forest with substantial understory vegetation and debris (e.g., logs, stumps), often in canyons along riparian edges of pine-oak forest, such as among horsetails near a spring in dense woodland (oak, walnut maple, sycamore, and some Douglas-fir), in thick woodland where large boulders were present with large pines, walnuts, oaks, and maples, and along a dry wooded streambed (Hoffmeister 1986, Simons and Van Pelt 1999, Simons and Hoffmeister 2003).

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Habitat and Ecology

Habitat and Ecology
This species occupies forested slopes, and is often found near springs or other water sources where considerable vegetation cover exists (Wilson and Ruff, 1999). It is nearly always found beneath a thick canopy of vegetation (Simons, in Wilson and Ruff 1999). It has been collected in montane conifer forest and encinal and Mexican oak-pine woodland, in relatively mature forest with substantial understorey vegetation and debris (e.g., logs, stumps), often in canyons along riparian edges of pine-oak forest, such as among horsetails near a spring in dense woodland (oak, walnut maple, sycamore, and some Douglas-fir), in thick woodland where large boulders were present with large pines, walnuts, oaks, and maples, and along a dry wooded streambed.

Systems
  • Terrestrial
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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

Comments: Feeds primarily on insects and other small invertebrates. Forages actively under cover of forest litter.

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 6 - 80

Comments: This shrew is represented by a relatively small number of known occurrences or subpopulations. It is known from three mountain ranges in Arizona, one mountain range in New Mexico (see New Mexico Department of Fish and Game 1996), and one specimen from Mexico (Simons and Hoffmeister 2003). There are at least 15 documented occurrences in Arizona (11 occurrences are extant; S. Schwartz, pers. comm., 1997). Surveys conducted in 2001 documented the presence of this shrew at two locations within the Animas Mountains in New Mexico (Simons, unpub. data).

This shrew is difficult to distinguish from S. monticolus (Arizona Game and Fish Department 1997), and it is difficult to capture in pitfall traps even in at known localities (see Simons et al. 1990). It seems possible that this species will be found in additional mountain ranges near the known range (Frey 2004).

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Global Abundance

2500 - 1,000,000 individuals

Comments: Total adult population size is unknown but presumably is at least a few thousand. Simons and Van Pelt (1999) reported that S. arizonae occurred widely in two mountain ranges in Arizona and was reasonably abundant at several sites.

This shrew has been reported as rare and extremely localized in New Mexico (see New Mexico Department of Game and Fish 1996).

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General Ecology

Little information available. May occur with S. MERRIAMI and S. MONTICOLUS.

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Life History and Behavior

Cyclicity

Comments: Active throughout the year. Periods of activity followed by periods of rest throughout the day and night.

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Reproduction

Nothing known about this species, but the closely related Merriam's shrew is known to produce litters of 5-7 young, born in the summer.

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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N2 - Imperiled

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NatureServe Conservation Status

Rounded Global Status Rank: G3 - Vulnerable

Reasons: The status of this shrew is poorly documented, but it occurs in several locations in at least five mountain ranges in Arizona, New Mexico, and northern Mexico, and it is probably more widely distributed than currently known. Trend is not known, and threats are unclear (but probably not too severe). Potential threats include removal of downed woody debris through understory clearing and firewood collection; intense ground-burning fires that remove ground structure could cause local extirpations; possibly threatened by livestock grazing and development of recreation sites in Arizona.

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Woodman, N., Matson, J. & Castro-Arellano, I.

Reviewer/s
Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Least Concern because of its wide distribution, occurrence in a number of protected areas, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.

History
  • 1996
    Vulnerable
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Status

Vulnerable.
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Global Long Term Trend: Increase of 10-25% to decline of 30%

Comments: Long-term trend is unknown, but there appears to be little reason to suspect that a major change has occurred in the extent of occurrence, area of occupancy, number of subpopulations, or population size.

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Population

Population
This species was only known from a few specimens from the Animas Mountains of New Mexico and the Sierra Madre Occidental of Chihuahua, Mexico until surveys initiated by the Arizona Game and Fish Dept in 1992 and 1993 found 30 more specimens (increasing the reported individuals known from 22 to 52) (Wilson and Ruff, 1999). This shrew may be more abundant and widespread than records suggest (Wilson and Ruff, 1999). In Mexico it is known only from one specimen in Chihuahua at 2,600 m asl (Carraway, 2007).

Population Trend
Unknown
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Threats

Degree of Threat: Medium

Comments: If this species is as rare and restricted in distribution as it appears to be in some areas (e.g., Animas Mountains, New Mexico), it may be vulnerable to localized adverse habitat alterations (see New Mexico Department of Game and Fish 1996). Potential threats include habitat alteration and degradation caused by removal of downed woody debris through understory clearing and firewood collection; intense ground-burning fires that remove ground structure could cause local extirpations (Arizona Game and Fish Department 1996). Locally, this shrew might be threatened by livestock grazing and development of recreation sites in Arizona (see New Mexico Department of Game and Fish 1996). However, the responses of this species to various habitat alterations and management practices are poorly known, and the scope of threat could not be determined in this assessment.

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Major Threats
If this species is as rare and restricted in distribution as it appears to be in some areas (e.g., Animas Mountains, New Mexico), it may be vulnerable to localized adverse habitat alterations. Potential threats include habitat alteration and degradation caused by removal of downed woody debris through understorey clearing and firewood collection; intense ground-burning fires that remove ground structure could cause local extirpations. Locally, this shrew might be threatened by livestock grazing and development of recreation sites in Arizona. However, the responses of this species to various habitat alterations and management practices are poorly known.
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Management

Biological Research Needs: More information is needed on life history and habitat requirements.

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Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Some occurrences are in Fort Huachuca Military Reservation and Coronado National Forest, but this does not necessarily ensure protection.

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Conservation Actions

Conservation Actions
It occurs in protected areas in Arizona (John Matson pers. comm.).
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Wikipedia

Arizona shrew

The Arizona shrew (Sorex arizonae) is a species of shrew native to North America.

Description[edit]

The Arizona shrew is one of the smaller species of shrew, with a head and body 5 to 7 cm (2.0 to 2.8 in) in length, and a tail about 4 cm (1.6 in) long. When filly grown, they weigh an average of only 3.5 g (0.12 oz). Their fur ranges from grey to brown, and is paler on the underparts of the animal.[2] Long thought to be the same as Merriam's shrew, it was identified as a separate species in 1977, and can be physically distinguished only by fine details of the skull and teeth.[3]

Distribution and habitat[edit]

The Arizona shrew is found in Chihuahua in Mexico, and in southern Arizona and New Mexico in the United States.[1] It inhabits forested mountainous terrain between 1,575 and 2,590 m (5,167 and 8,497 ft) dominated by coniferous trees or by mixed pine and oak. There are no known subspecies.[2]

Biology[edit]

Arizona shrews inhabit primary forest with heavy undergrowth, and are particularly common in mesic riverine canyons. Despite their preference for such canyons, they are not necessarily found close to open water. They apparently breed between late July and October.[2] They are believed to have diverged from the closely related Merriam's shrew relatively recently, during the late Pleistocene or early Holocene.[4]

References[edit]

  1. ^ a b Woodman, N., Matson, J. & Castro-Arellano, I. (2008). "Sorex arizonae". IUCN Red List of Threatened Species. Version 2009.2. International Union for Conservation of Nature. Retrieved 8 February 2010. 
  2. ^ a b c Simons, L.H. & Hoffmeister, D.H. (2003). "Sorex arizonae". Mammalian Species: Number 732: pp. 1–3. doi:10.1644/732. 
  3. ^ Diersing V.E. & Hoffmeister, D.H. (1977). "Revision of the shrew Sorex merriami and a description of a new species of the subgenus Sorex". Journal of Mammalogy 58 (3): 321–333. doi:10.2307/1379331. 
  4. ^ George, S.B. (1988). "Systematics, historical biogeography, and evolution of the genus Sorex". Journal of Mammalogy 69 (3): 443–461. doi:10.2307/1381337. 
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Names and Taxonomy

Taxonomy

Comments: See George (1988) for electrophoretic study of systematic relationships among Sorex species. First described in 1977 (Diersing and Hoffmeister 1977); electrophoretic data support separation of this species from S. merriami (George 1988).

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