Nicobar Shrew

The Nicobar Shrew is a tiny, poorly known insectivorous mammal endemic to Great Nicobar Island in the Indian Ocean. It is one of the rarest and most range-restricted shrews in the world, known only from a handful of specimens. Its extreme rarity and highly restricted island distribution make it one of the most critically endangered small mammals in South Asia. Almost nothing is known of its ecology due to the scarcity of records since its description.

Great Nicobar Island, India (Nicobar Archipelago, Bay of Bengal)

Endemic to Great Nicobar Island, part of the Nicobar Archipelago in the Bay of Bengal, India; no records exist from other islands in the group.

Altitude and depth

Likely lowland forest, approximately 0-300 meters elevation

Believed to inhabit tropical evergreen and moist forest floor leaf litter on Great Nicobar Island, though precise habitat preferences remain poorly documented. It likely relies on humid forest understorey with abundant invertebrate prey and leaf litter cover.

Adaptations to its environment

As a small insectivore, it likely possesses a high metabolic rate and continuous need for feeding typical of shrews, along with a keen sense of smell and touch (vibrissae) for locating invertebrate prey in leaf litter. Its small body size may be an adaptation to the limited resource base of a small tropical island ecosystem.

Critically Endangered (IUCN) due to its extremely restricted range (single island), very few known records, and ongoing habitat degradation; data are insufficient to determine population trend with confidence but presumed declining.

Estimated population

Unknown; population size has never been reliably estimated due to the rarity of specimens and lack of systematic surveys, presumed to be very small and declining.

Habitat loss from deforestation, agricultural expansion, and infrastructure development on Great Nicobar Island, compounded by the 2004 tsunami which severely impacted coastal and low-lying habitats; introduced predators such as rats and feral cats also pose threats.

Great Nicobar Island includes some protected areas such as the Great Nicobar Biosphere Reserve, which may offer indirect protection to remaining habitat; no species-specific conservation program exists for this shrew.

Recommended actions

Conduct dedicated field surveys to confirm continued existence and assess distribution, protect remaining primary forest habitat from development projects, and control invasive predators on the island.

Small shrew with soft, dense grayish-brown to dark brown dorsal fur, paler underparts, a pointed snout, small eyes, and a moderately long tail covered with fine hairs.

Size

Body length approximately 60-70 mm (head-body), similar to other small Crocidura shrews

Weight

Estimated 4-8 grams, typical for small Crocidura species

Distinctive features

Distinguished from other Crocidura species primarily by subtle cranial and dental characteristics identified in its original taxonomic description, as external morphology is similar to related shrews.

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

When it is active

Likely nocturnal or crepuscular, consistent with the general activity pattern of shrews, though direct behavioral observations are lacking.

Diet

Presumed insectivorous, feeding on small invertebrates such as insects, worms, and other arthropods found in leaf litter, typical of the genus Crocidura.

How it feeds and hunts

Likely forages by actively searching leaf litter and soil using its sensitive snout and whiskers to detect prey by touch and smell, as is typical for shrews.

Communication

Likely uses high-frequency vocalizations, scent marking via specialized glands, and tactile cues, consistent with other Crocidura shrews.

Interactions with other species

Likely preyed upon by owls, snakes, and introduced predators such as feral cats and rats; may compete with other small insectivores for invertebrate prey on the island.

Role in its ecosystem

Plays a role as a small invertebrate predator within the forest floor ecosystem, potentially helping regulate insect and other invertebrate populations on Great Nicobar Island.

No specific data available; likely follows the general Crocidura pattern of short gestation (around 25-30 days) and multiple small litters per year in suitable conditions.

Raising the young

Presumed maternal care only, with females raising altricial young in a nest until weaning, typical of shrew reproductive biology.

Maturity and lifespan

Unknown specifically, but likely similar to related Crocidura species with maturity reached within a few months and a short lifespan of 1-2 years in the wild.

Classification

Class Mammalia > Order Eulipotyphla > Family Soricidae > Genus Crocidura > Species Crocidura nicobarica

Recent studies

Very few studies exist beyond its original taxonomic description; recent biodiversity surveys on Great Nicobar Island have not consistently reported new confirmed sightings, raising concern about its status.

Compared with similar species

Similar in general appearance to other Indian Ocean island Crocidura species such as the Andaman Spiny Shrew, but distinguished by specific cranial morphology and its exclusive endemism to Great Nicobar Island.

It is known from only a very small number of museum specimens, making it one of the most enigmatic mammals in India. Its entire known world range is confined to a single island smaller than many cities.

Where and how to see it

Extremely difficult to observe due to its rarity and elusive nocturnal habits; any potential observation would require specialized trapping surveys conducted by researchers in Great Nicobar's forest interior with proper permits.

Risks to humans

No notable risk