Jenkin's Shrew

Jenkin's Shrew is a critically endangered small insectivorous mammal endemic to Silhouette Island in the Seychelles. It is one of the rarest shrews in the world, confined to a single small island habitat. Its extremely restricted range and small population make it highly vulnerable to extinction. The species is remarkable as an example of island endemism and evolutionary isolation.

Seychelles (Silhouette Island)

Endemic to Silhouette Island, part of the Seychelles archipelago in the Indian Ocean. This is its only known locality, making it one of the most geographically restricted mammal species in the world.

Altitude and depth

Approximately 200-750 meters above sea level, with concentration in higher elevation forest zones.

Found primarily in moist mountain forest, mist forest, and glacis (granite outcrop) habitats with leaf litter and dense vegetation. It appears to prefer higher elevation forest areas with cooler, moister conditions on Silhouette Island.

Adaptations to its environment

As a small insectivore, it has a high metabolic rate typical of shrews, requiring frequent feeding. Its restriction to moist upland forest suggests physiological adaptation to cooler, more humid microclimates compared to lowland areas of the island.

Critically Endangered (CR) according to IUCN, due to its extremely small range confined to one island, fragmented habitat, and very low population numbers. Any localized disturbance such as habitat degradation or invasive species could cause rapid decline.

Estimated population

Population size is unknown but presumed to be very small given the tiny range; trend is suspected to be declining or at best stable, with high uncertainty due to limited survey data.

Main threats include habitat degradation from introduced plant species, predation or competition from invasive mammals (rats, cats), and the inherent vulnerability of having a single-island distribution susceptible to stochastic events like cyclones or disease outbreaks.

Silhouette Island is largely protected within the Silhouette National Park, which restricts development and helps preserve native forest habitat. Conservation organizations have conducted some survey work to better understand the species' distribution and ecology.

Recommended actions

Priority actions include systematic population surveys, invasive species control (particularly rats and cats), habitat protection and restoration, and long-term monitoring to track population trends and detect threats early.

Likely has grayish-brown to dark brown dorsal fur with paler underparts, a pointed snout, small eyes, and the characteristic elongated shrew body shape. Fine short fur covers the body typical of the genus.

Size

Head-body length approximately 55-70 mm, with a tail of similar or slightly shorter length, consistent with other Crocidura shrews.

Weight

Estimated 4-8 grams, typical of small Crocidura species.

Distinctive features

Distinguished from other Crocidura species by subtle differences in skull morphology, dentition, and its exclusive occurrence on Silhouette Island, which sets it apart geographically from mainland and other island shrews.

Presumed solitary, as is typical for most Crocidura shrews, with limited social interaction outside of breeding encounters.

When it is active

Likely nocturnal or crepuscular, consistent with the general activity pattern of shrews, foraging for invertebrates under cover of darkness or twilight.

Diet

Insectivorous, feeding on small invertebrates such as insects, larvae, and other small arthropods found in leaf litter and forest floor substrate.

How it feeds and hunts

Forages actively through leaf litter and undergrowth using its sensitive whiskers and keen sense of smell to locate small invertebrate prey.

Communication

Likely uses ultrasonic vocalizations and scent marking typical of shrews for communication, though specific studies on this species are lacking.

Interactions with other species

Faces potential predation and competition pressure from invasive species such as rats and feral cats introduced to the island; may also interact with native reptiles and birds as part of the forest ecosystem.

Role in its ecosystem

Plays a role as an insectivorous predator within the forest ecosystem, helping regulate invertebrate populations and contributing to nutrient cycling through its foraging activity.

Specific reproductive data for this species is lacking, but likely follows the general Crocidura pattern with short gestation (around 20-30 days) and small litters of a few young.

Raising the young

Presumed maternal care typical of shrews, where the female raises the altricial young alone in a nest until they are weaned and independent.

Maturity and lifespan

Data specific to this species is limited, but based on related Crocidura shrews, sexual maturity is likely reached within a few months, with a wild lifespan typically around 1-2 years.

Classification

Mammalia > Eulipotyphla > Soricidae > Crocidura > Crocidura jenkinsi

Recent studies

Recent conservation assessments have focused on refining distribution data and habitat requirements on Silhouette Island, though detailed ecological studies remain scarce due to the species' rarity and difficulty of study.

Compared with similar species

Similar to other Seychelles and African Crocidura shrews but distinguished by its extremely limited endemic range; compared to the more widespread Crocidura species, it has a much smaller and more vulnerable population.

Jenkin's Shrew is found nowhere else on Earth except one small island, making it one of the most range-restricted mammals known. It was only formally described relatively recently, highlighting how much remains to be discovered about small island endemics.

Where and how to see it

Observation is extremely difficult due to its nocturnal habits, small size, and restricted range; visiting protected forest areas of Silhouette Island with a permit and guided ecological tour offers the best (though still unlikely) chance of any sign of its presence.

Risks to humans

No notable risk to humans.