Sorex longirostris

Geographic Range

Southeastern shrews ( Sorex longirostris ) are prominently found in the southeastern United States. They are found as far south as central Florida and as far north as central Illinois and southern Maryland. Southeastern shrews are found as far west as eastern Oklahoma, and eastward along the east coast of the United States.

Two subspecies of southeastern shrews are recognized by some researchers. Dismal Swamp southeastern shrews ( Sorex longirostris fisheri ) are found in the Suffolk, Virginia Beach, Chesapeake, and Southhampton counties of Virginia. They are also located in Gates, Currituck, Pasquotank, Perquimans, and nearby counties in North Carolina. The subspecies Sorex longirostris eionis is endemic to all of Florida. The name of the third subspecies that inhabits the remainder of the geographic range has not been reported in recent literature.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Southeastern shrews are typically found in old fields, forests, or wetlands. They are most commonly found in upland hardwood forests. In all of these areas, they inhabit moist areas with thick ground cover. They are typically found where vines, briars, and tall grass are abundant. Japanese honeysuckle ( Lonicera japonica ), bush clover ( Lespedeza cuneata ), and greenbrier (genus Smilax ) are commonly found in areas that southeastern shrews inhabit. Dismal Swamp southeastern shrews are found in the same environments, but are more likely to inhabit wetlands.

An elevation range for southeastern shrews has not been determined due to their wide geographic and habitat range.

Their nests are often built inside rotting logs near water. These nests are built with leaves and grass deep within the log, and have been described as bulky and matted.

• Habitat Regions
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• mountains mountains

• Wetlands
• marsh marsh
• swamp swamp
• bog bog

• Other Habitat Features
• agricultural agricultural

Physical Description

Southeastern shrews can grow to a maximum weight of 6 g, but are typically between 2 to 4 g, and have a maximum length of 110 mm (range: 68 to 110 mm). Whitaker Jr. and Hamilton Jr. (1998) took measurements of 270 southeastern shrews in Alabama and Georgia. These shrews had the following average measurements: total length 81.9 mm, tail length 30.1 mm, and hind foot length 10.9 mm. Whitaker Jr. and Hamilton Jr. conducted another study with 33 southeastern shrews in Indiana, whose measurements were the following: total length 72 to 90 mm, tail length 26 to 33 mm, hind foot length 9 to 11 mm, and weight 3 to 4 grams.

Southeastern shrews are characterized by long, bicolored tails, small ears hidden by fur, small eyes, and long, pointed snouts. Their ventral fur varies from grayish brown to dark black, but their dorsal fur is reddish-gray. Dismal swamp southeastern shrews have a browner coat color on their ventral sides and a duller color on their dorsal sides. Southeastern shrews have skulls that measure 14 to 17 mm in length and 7 mm in width. Their skulls are characterized by flattened braincases and broad rostra. The dental formula for southeastern shrews is 3133/1113, totaling 32 teeth. Males weigh 1 gram more than females, on average. Females have a greater palatal length and maxillary tooth row. Adult males have an average penis length of 15 mm.

Not much data have been collected on newborn southeastern shrews, but there are some data about juveniles. French (1980) reported that nestlings that are almost fully grown have total lengths measuring 71 to 72 mm. Although there are not much data about newborn southeastern shrews, some data about a closely-related species, masked shrews ( Sorex cinereus ), has been collected. In a sample of fifteen newborn masked shrews, Forsyth (1976) reported an average weight of 0.28 g and total length of 12 to 14 mm. When they are born, their skin is transparent, they have no hair, and they appear to be dark pink. They lack claws and their limbs are not fully developed. Their eyelids are closed, and their ears are closed and fused to their head. After 17 to 18 days their eyes open and, after 14 to 17 days, their ears open. Their claws are fully grown after 16 to 17 days and their fingers and toes are separated after 15 to 16 days. After 20 days their fur is fully is grown, their teeth are developed, but still covered by gum tissue, and they have an average weight of 3.5 g. It is presumed that nestling southeastern shrews follow a growth pattern similar to this.

Southeastern shrews are often confused with other shrews like pygmy shrews ( Sorex hoyi ). Southeastern shrews can be distinguished from pygmy shrews by their size. Pygmy shrews are smaller in size and have smaller third and fifth unicuspids.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes shaped differently

Reproduction

Southeastern shrews typically breed at least twice per year. Little is known about the mating behavior of southeastern shrews, but there are data about the mating systems of other Sorex species. Searle (1990) found that male common shrews ( Sorex araneus ) attempted to mate with females up to 15 times while the females were in heat. Males mate with different females throughout the breeding season. Blossom (1932) anecdotally reported on the mating behavior of a pair of common shrews. He found that females would follow males around and then lay on their backs when they were ready to mate. When females did not want to mate, they would bite and squeak at prospective males until they left females alone. Southeastern shrews are polygynandrous, meaning that males and females mate with different partners throughout their life.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

The breeding season for southeastern shrews spans from March to October. Females typically have at least two litters throughout the breeding season. Their first litter is usually born in March or April, but it is common for the young to die due to cold weather. On average, they have 4 offspring per litter (range 2 to 6), which are born blind, deaf, and naked. Their gestation period is 18 days. The mass of juvenile southeastern shrews has not been reported, but data about a closely related species, masked shrews ( Sorex cinereus ), suggests that the average weight of newborns is 0.28 g. Young southeastern shrews are weaned after 5 to 6.5 weeks. Masked shrews are independent after about 27 days; it’s likely that southeastern shrews follow a similar time scale.

French (1980) found that female southeastern shrews reach sexual maturity between 6 and 12 weeks old, even though they are still considered to be immature. However, it is considered rare for females to be sexually mature at 6 to 12 weeks old; French suggested that low population densities may expedite sexual maturity at this age. It is more common for females to become sexually mature when they are between 30 and 36 weeks old. French reported that males reach sexual maturity at about 24 to 30 weeks. Foresman (1998) reported that male masked shrews reach sexual maturity at 11 months.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

After litters are born, female southeastern shrews nurse and protect their young. Females build nests for their young before giving birth. They build these nests in places like the inside of rotting logs. After mating, females abandons their male mates. Males do not have any involvement with their offspring. Juvenile southeastern shrews are born blind, deaf, and naked. Mothers nurse their young until they are 5 to 6 weeks old. Even after juveniles have been weaned, they are still dependent on their mother. Mothers teach their young how to hunt and protect them from predators until they leave the nest. Young southeastern shrews remain in their nests until they are nearly fully grown.

• Parental Investment
• altricial altricial
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female
• extended period of juvenile learning

Lifespan/Longevity

Like other shrews, southeastern shrews have a relatively short lifespan. In captivity, they can live between 18 and 22 months. Most southeastern shrews do not survive more than one winter in the wild. Their average lifespan in the wild is approximately 12 months. Not much more is known about their lifespans in the wild.

Behavior

Southeastern shrews are active at all hours of the day, but their activity is limited to short periods. Because keeping them alive after trapping them in the wild is difficult, there is not much information on their behavior in natural habitats. However, research on other species in the Sorex genus shows that when eating, they bite their prey rapidly to kill it before eating it. Because their metabolism is so high, they spend most of their time foraging for food and eating. They typically burrow into the soil before creating nests with grass, moss, leaves, and other materials they can find around them.

In captivity, southeastern shrews are solitary animals, but will live together in the same nest until they are about 2 months old. Some cases have been reported of southeastern shrews living in pairs or small groups in the wild. On average, there are 12 to 18 southeastern shrews per acre in their natural habitat. They are also territorial about their nests. When threatened near their nest, they will squeak and briefly charge at intruders. Their most common response to coming across another shrew is to keep their distance and leave it alone. Sometimes they will approach and sniff other shrews and then cease direct interactions.

In captivity, masked shrews ( Sorex cinereus ) would fight in close quarters, and could jump up to 15 cm. They groomed their full bodies with their feet. It is suspected that southeastern shrews may have similar behaviors.

• Key Behaviors
• terricolous
• fossorial fossorial
• diurnal diurnal
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• solitary solitary
• territorial territorial

Home Range

Not much is known about the home range of southeastern shrews. Species in the genus Sorex have many behaviors and traits in common with southeastern shrews, so it is assumed that they have a comparable home range size to other shrews. Hawes (1977) found that the average home range for vagrant shrews ( Sorex vagrans ), a similar species, was 1,039 m^2 for non-breeding shrews. Breeding individuals have an average home range of 3,258 m^2, which is over twice the range of non-breeding individuals. When males are breeding, they tend to have a larger home range than females. Both females and males have about the same home range if they are not breeding. Home ranges tend to overlap because male shrews will go outside of their home range in order to breed. Shrews will still fight to defend their territory against any species of shrew that comes too close.

Communication and Perception

Southeastern shrews make high-pitched chirping noises that resemble those of birds. The sounds they make are often at such high frequencies that they are inaudible to human ears. Choate et al. (1994) found that their chirps have a frequency of 20 kHz. Researchers note that they make these sounds in order to echolocate. They also make clicking and buzzing sounds. Southeastern shrews communicate with pheromones as well. They have scent glands on their flanks that cause an odor. The purpose of these glands is to attract potential mates.

• Communication Channels
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• echolocation echolocation
• chemical chemical

Food Habits

Southeastern shrews are insectivores. Their diet consists of spiders, centipedes, beetles, lepidopteran and coleopteran larvae, crickets, snails, slugs, worms, harvestmen, and some vegetable matter. Their most common foods are spiders, crickets, and butterfly larvae. They are also known to eat seeds. French (1984) found that 39.3% of their diet is from the order Araneae (spiders), 15.7% is larvae from the order Lepidoptera (moths/butterflies), 11.5% is from the order Orthoptera (grasshoppers), 5.8% is from the order Phalangida (harvestmen), 4.1% is larvae from the order Coleoptera (beetles), 3.9% is from the order Chilopoda (centipedes), 3.5% is from the order Hemiptera (true bugs), 3.7% is adults from the order Lepidoptera (moths/butterflies), 7.1% is adults from the order Coleoptera (beetles), 1.4% is from the order Isopoda (pill bugs), 1% is from the order Chilopoda (centipedes), 1% is from the order Homoptera (true bugs), and 1% is from the order Hemiptera (true bugs). They are opportunists and live in habitats where food is plentiful for them.

Southeastern shrews spend a lot of their time finding food. They hunt for insects and forage for seeds and vegetable matter almost all day. This is because they must eat at least 50% of their body weight every day in order to live, due to their high metabolic demands.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
  • molluscivore molluscivore
  • vermivore
• herbivore herbivore
  • granivore granivore

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

• Plant Foods
• seeds, grains, and nuts

Predation

The most common predators of southeastern shrews are barn owls ( Tyto alba ) and barred owls ( Strix varia ). They have scent glands on their flanks to deter predators. Southeastern shrews also tend to stay in or around dense brush, which camouflages them. If a predator attacks, they are able to run away quickly. Other predators include domestic cats ( Felis catus ), Virginia opossums ( Didelphis virginianus ), red foxes ( Vulpes vulpes ), gray foxes ( Urocyon cinereoargenteus ), bobcats ( Lynx rufus ), striped skunks ( Mephitis mephitis ), eastern spotted skunks ( Spilogale putorius ), long-tailed weasels ( Mustela frenata ), least weasels ( Mustela nivalis ), and snakes. Specifically, cottonmouth snakes ( Agkistrodon piscivorus ) are known predators of southeastern shrews.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Southeastern shrews are vital prey for animals in their habitats, including birds, reptiles, and other mammals. They eat insects and disperse seeds and fungal spores.

Southeastern shrews are affected by a number of mites including Orycteroxenus soricis ohioensis , Euschongastia blarinae , Pygmephorus horridus , Protomyobia indianensis . They are also affected by protozoan parasites such as Eimeria palustris . Other parasites that affect southeastern shrews include nematodes (genus Porrocaecum ) and whipworms (genus Capillaria ).

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Shrews could potentially control pest populations. Masked shrews ( Sorex cinereus ) are known to eat cocoons of European pine sawflies ( Neodiprion sertifer ) that are commonly found in forests. This benefits the forestry industry.

Economic Importance for Humans: Negative

There are no known negative economic impacts of southeastern shrews on humans.

Conservation Status

The IUCN Red List has listed southeastern shrews as a species of "Least Concern" and they are not on CITES or the State of Michigan list. The US Federal list has Dismal Swamp southeastern shrews listed as "Delisted due to Original Data in Error - New Information Discovered." In 2000, Dismal Swamp southeastern shrews were removed from the US Federal list because the U.S. Fish and Wildlife Service concluded their population has increased, they occur in various habitats, and are genetically secure ("65 FR 10420 - Endangered, threatened wildlife, and plants; delisting of the Dismal Swamp southeastern shrew (Sorex longirostris fisheri)", 2000).

Although there are no major threats to southeastern shrews, the threats they do face are caused by humans. Plastic bottles that have been improperly disposed of along highways are a cause of death for many animals, including southeastern shrews. Destruction and development of their habitats cause declines in their population as well. Deforestation greatly affects the availability of fallen trees and rotting logs in which these shrews build their nests. Researchers contribute to shrew mortality rate by trapping live shrews and not putting them in captivity before they starve. In the past, threats to Dismal Swamp southeastern shrews included habitat disturbance and possible interbreeding.

Currently, there are no conservation efforts being made for southeastern shrews because they are not threatened or endangered. Before being removed from the U.S. Federal list of endangered and threatened species, conservation efforts were made to protect Dismal Swamp southeastern shrews. The U.S. Fish and Wildlife Service declared them to be a protected species and efforts were made to stop certain practices, like the use of the Dismal Swamp canal, that negatively impacted Dismal Swamp southeastern shrews.

Additional Links

Encyclopedia of Life

Contributors

Raegan Forbes (author), Radford University, Lauren Burroughs (editor), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.

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