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Sorex gaspensisGaspé shrew

By Nicole Munkwitz

Geographic Range

The geographic range of the Gaspé shrew covers select mountainous regions of eastern North America. In 1974, fifty years after it was first described (Anthony and Goodwin 1924), a relict population of Sorex gaspensis was discovered inhabiting Cape Breton Highland National Park, Nova Scotia. Today populations exist in three disjunct locations in Canada: 1) the Gaspé peninsula of southeastern Québec, 2) north central and western New Brunswick, and 3) Cape Breton Island, Nova Scotia. (Kirkland, 1999; Roscoe and Majka, 1976)

Habitat

What is known about S. gaspensis habitat preferences has been learned from limited trapping occurrences throughout its range. These shrews are found in boreal spruce or mixed deciduous forests. They occur in areas of leaf-litter, or moss-covered, rocky terrain. They have been trapped at elevations from 290 to 490 m.

S. gaspensis is trapped in areas with habitat similar to the habitat of water shrews, S. palustris. Trap sites of the Gaspé shrew are often associated with small brooks or tributaries. However, the habitat of the Gaspé shrew is more often compared to that of the rock shrew, S. dispar. Both S. gaspensis and S. dispar fill the niche of living in and among rocks in higher elevations, but the two are not sympatric. (Kirkland, 1981; Kirkland, 1999; Roscoe and Majka, 1976)

  • Range elevation
    290 to 490 m
    951.44 to 1607.61 ft

Physical Description

Gaspé shrews are slate-gray in color with the dorsal side slightly darker than the ventral side. There is no known seasonal variation in pelage color. The tail is not bi-colored and is relatively long, measuring an average of 49.7 mm. This length is between 80 and 90 per cent of the head-body length. (Kirkland, 1981)

S. gaspensis is characterized as small and slender, most notably in the skull. The ‘delicately constructed’ skull has a very narrow rostrum. It is characterized as ‘non-angular’ and very depressed. Weights recorded for trapped specimens range from 2.2 to 4.3 g. (Kirkland and Van Deusen, 1979)

The external characteristics of S. gaspensis should easily distinguish it from all other sympatric Soricidae. (Kirkland, 1981)

Although the two look very similar, S. gaspensis is generally distinguished from its closest relative, S. dispar, by its overall smaller size, slightly paler coloration, weaker dentition, and the proportionally larger hind foot to body size. As well, the range of possible condylobassal (15.35–16.35 mm; n=18) and the molariform tooth row (3.40-3.65mm; n=18) lengths only rarely overlap for the two species. S. dispar has lengths greater than those given above. (French and Kirkland Jr., 1983; Kirkland, 1981)

  • Range mass
    2.2 to 4.3 g
    0.08 to 0.15 oz
  • Range length
    95 to 127 mm
    3.74 to 5.00 in
  • Average length
    105 mm
    4.13 in

Reproduction

The breeding system of S. gaspensis as not been described, as so few animals of this species have ever been captured. However, males of other species of Sorex compete for access to females, and are probably polygynous. (Nowak and Paradiso, 1983)

Nothing was known about the reproductive cycle of Gaspe shrews until three pregnant females were captured in 1980. The first two, both with six embryos, were trapped between 16 June and 20 July. The third pregnant female, with five embryos, was captured between 21 and 23 July. Of the 67 S. gaspensis trapped during this time the majority (93%) were young of the year, but it is not known if they were independent by the time they were trapped. (French and Kirkland Jr., 1983)

In general, species from the genus Sorex have a gestation period that lasts between 18 and 28 days. Often the young are born in nests constructed out of vegetation and young are weaned and independent four to five weeks later. Females first breed in the second year although sometimes they have been know to breed in their first year when there is a low population density. (Nowak and Paradiso, 1983)

  • Breeding interval
    It is unknown how frequently this species breeds.
  • Breeding season
    Based on capture of pregnant females, these animals breed in the Spring and Summer.
  • Range number of offspring
    5 to 6

Nothing is known about the parental behavior of this species, except what can be inferred from general patterns within the genus. In the genus Sorex, the mother typically cares for the young, nursing them and protecting them in some sort of nest, until they are approximately four weeks old. It is not nown whether the male participates in care of the young. (Nowak and Paradiso, 1983)

  • Parental Investment
  • altricial
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

The life span of S. gaspensis is unknown, however, species from the genus Sorex typically live between one and two years. (Nowak and Paradiso, 1983)

Behavior

The behavior of S. gaspensis is not known. However species of the genus Sorex tend to be solitary and highly aggressive toward one another. It is likely that Gaspe shrews are like their congeners in this respect. (Nowak and Paradiso, 1983)

Memebers of the genus Sorex are often active both day and night. Although they may sleep very deeply, when they are awake, they are very quick and active, darting from here to there. Home ranges for these animals range from 532 to 5,261 square meters. and may vary seasonally. (Nowak and Paradiso, 1983)

Home Range

The home range of S. gaspensis is not known.

Communication and Perception

Communication in this species has not been described, as captures tend to be made in pit-fall traps. However, it is likely that, as in most mammals, there is some tactile, accoustic,and chemical communication. Most shrews don't seem to have really well developed eyes, so it seems unlikely that visual communication, especially over distance, plays an important role in this species. (Kirkland, 1999)

Food Habits

The stomach contents of 62 Gaspé shrews trapped during the summer of 1980 were examined to better understand the composition of their diet. Insect larvae and spiders were found to make up 25 percent and 23 percent of the stomach contents, respectively. Spiders were recognized as the single most important arthropod order in the diet of these animals, because of the myriad orders from which the other insect larvae came. Beetles (Coleoptera) and flies (Diptera) were the next most abundant specimens found at 10.6 percent and 11.8 percent in the stomach contents respectively. Overall, adult insencts comprized half of the stomach contents. Although not common, earthworms, and snails, and slugs were also found in the stomachs of S. gaspensis. (Whitaker and French, 1984)

Plant matter was found in two specimens of S. gaspensis trapped during the summer of 1953. (Hamilton and Hamilton III, 1954)

It is believed that a great deal of hunting takes place in crevices and fissures of the rocky habitat these shrews occupy. Hence, with its small size, slender body, narrow rostrum and procumbent incisors, S. gaspensis is well adapted for its feeding ecology. (Hamilton and Hamilton III, 1954; Kirkland, 1999)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms

Predation

The predators of these animals have not been described. However, as with most small mammals, they probably are victims of predation by sympatric canids, felids, mustelids, hawks, and owls. It is not known if the rapid, darting movement common in the genus Sorex is an adaptation to finding food rapidly, or making capture by predators more difficult.

Ecosystem Roles

It is difficult to speculate on the ecological importance of these shrews. The species is distributed over a very small area, and densities do not appear to be very high. However, it is likely that these animals affect populations of the species upon which they prey (at least in a very local way). They may also have some impact on predator populations, although it is unlikey that any predator species would be able to rely heavily upon these animals.

Economic Importance for Humans: Positive

There is no known positive impact of these animals on humans.

Economic Importance for Humans: Negative

Gaspé shrews have no known negative effects on humans.

Conservation Status

Due to extremely low trapping success until 1980, Gaspé shrews were formerly considered one of the rarest mammals in North America. Currently, S. gaspensis is listed as a species of special concern in Canada by the Committee on the Status of Endangered Wildlife in Canada.

The Atlantic Canada Conservation Data Center (AC CDC) has given S. gaspensis the following species rarity ranks following the standardized system of the Nature Conservancy and United States Natural Heritage Programs: Global rank of G3, species rarity rank in New Brunswick of S1 and species rarity rank in Nova Scotia of S2.

G3 is defined as, "Either very rare and local throughout its range (21-100 occurrences or less than 10,000 individuals) or locally in a restricted range or vulnerable to extinction from other factors."

S1 is defined as, "Extremely rare throughout its range in the province (typically 5 or fewer occurrences or very few individuals). May be especially vulnerable to extirpation."

S2 is defined as, "Rare throughout its range in the province (6 to 20 occurrences or few remaining individuals). May be vulnerable to extirpation due to rarity or other factors." ("Atlantic Canada Conservation Data Centre", 2003)

Other Comments

Due to the Wisconsin Glaciation and current waterways preventing any northern movement, S. gaspensis is one of only two boreal mammals whose range lies completely south of the St. Lawrence river. (Kirkland and Van Deusen, 1979)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Nicole Munkwitz (author), Humboldt State University, Brian Arbogast (editor), Humboldt State University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2003. "Atlantic Canada Conservation Data Centre" (On-line). Accessed February 20, 2004 at http://www.accdc.com/.

Anthony, H., G. Goodwin. 1924. A new species of shrew from the Gaspé Peninsula. American Museum of Natural History Novitates, 109: 1-2.

French, T., G. Kirkland Jr.. 1983. Taxonomy of the Gaspé shrew, *Sorex gaspensis*, and the rock shrew *S. dispar*. The Canadian Field-Naturalist, 97: 75-78.

Hamilton, W., W. Hamilton III. 1954. The food of some small mammals from the Gaspé Peninsula. The Canadian Field-Naturalist, 68(3): 108-109.

Kirkland, G., H. Van Deusen. 1979. The Shrews of the *Sorex dispar* group: *Sorex dispar* Batcher and *Sorex gaspensis* Anthony and Goodwin. American Musuem Novitates, 2675: 1-21.

Kirkland, G. 1981. *Sorex dispar* and *Sorex gaspensis*. Mammalian Species No. 155: 1-4.

Kirkland, G. 1999. Gaspé Shrew/ *Sorex gaspensis*. Pp. 24 in D Wilson, S Ruff, eds. The Smithsonian Book of North American Mammals. Washington and London: Smithsonian Institution Press.

Nowak, R., J. Paradiso. 1983. Walker's Mammals of the World. Fourth edition, vol.1. Baltimore and London: The Johns Hopkins University Press.

Roscoe, B., C. Majka. 1976. First records of the rock vole (*Microtus chrotorrhinus*) and the Gaspé shrew (*Sorex gaspensis*) from Nova Scotia and a second record of the Thompson's pygmy shrew (*Microsorex Thompsoni*) from Cape Breton Island. The Canadian Field-Naturalist, 90(4): 497-498.

Whitaker, J., T. French. 1984. Food of six species of sympatric shrew from New Brunswick. Canadian Journal of Zoology, 62(4): 622-626.

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