Grey musk shrew (suncus murinus caerulescens)

Zoological Profile, Taxonomy, and Urban Ecology of Suncus murinus (Asian House Shrew / Musk Shrew)

The Asian House Shrew (Suncus murinus), known in Sinhala as Hik-Miya (හික් මීයා) or Kunu-Miya (කුණු මීයා) and in Tamil as Mungi'eli (முஞ்சுறு) or Munjuru (மூஞ்சுறு), holds the distinction of being the largest shrew species present in Sri Lanka.

While frequently misidentified as a destructive rodent due to its superficial physical resemblance to rats, Suncus murinus is a true insectivore belonging to the order Eulipotyphla. It plays an invaluable role in urban sanitation by aggressively hunting household pests and displacing destructive rodent populations.

1. Taxonomy and Soricid Diversity in Sri Lanka

Sri Lanka is home to 10 distinct species within the shrew family (Soricidae), ranging from tiny montane endemic shrews to large synanthropic species. Unlike indigenous and endemic forest shrews, Suncus murinus is an exotic introduced species.

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Eulipotyphla

• Family: Soricidae (True shrews)

• Genus: Suncus

• Species: Suncus murinus (Linnaeus, 1766)

Key Soricid Species in Sri Lanka

Among Sri Lanka's 10 shrew species, several notable members include:

1. Asian House Shrew (Suncus murinus) — Largest shrew on the island; introduced urban synanthrope.

2. Sri Lanka Jungle Shrew (Suncus zeylanicus) — Endemic highland forest specialist.

3. Sri Lanka Mountain Shrew (Suncus montanus) — Endemic montane shrew found in wet zone cloud forests.

4. Horsfield's Shrew (Crocidura horsfieldii) — Small white-toothed shrew inhabiting varied biomes.

5. Sri Lanka Long-tailed Shrew (Crocidura miya) — Endemic wet-zone forest dweller.

2. Physical Morphology, Biometrics, and Color Variations

Suncus murinus possesses several anatomical hallmarks that differentiate it from native shrews and sympatric rodents.

Anatomical Measurements and Coat Dynamics

• Overall Body Length: Averages 246 mm (approx. 24.6 cm / 9.7 inches) in total length, making it significantly larger than all other native Sri Lankan shrews.

• Proportional Tail Length: Possesses the proportionately shortest tail relative to overall body size among Sri Lankan soricids.

• Musk Gland Development: Both males and females feature highly developed lateral flank glands that emit a distinct, pungent musty odor, which serves both as a territorial scent marker and a deterrent against predators.

• Pelage Pigmentation: It is the lightest-colored shrew species in Sri Lanka, but curiously, its pelage grows noticeably darker with age (unlike many mammals that lighten as they age).

• Genetic Pigment Variations: Partial albinism (albinos) and piebald patterns (skewbald individuals with irregular white patches) are relatively common in specific localized populations.

  Morphological Feature	Asian House Shrew (Suncus murinus)	Sri Lankan Endemic Shrews (Suncus zeylanicus / montanus)	House Rat (Rattus rattus)
  Total Length	~246 mm (Largest)	~100 – 150 mm (Medium/Small)	~300 – 400 mm
  Tail Proportion	Shortest relative tail	Medium to long tail	Very long tail (exceeds body length)
  Origin in Sri Lanka	Introduced (India)	Endemic / Native	Introduced / Native strains
  Habitat Preference	Urban buildings, towns, human dwellings	Primary rainforests & cloud forests	Houses, roofs, agricultural fields
  Odor Secretion	Strong musty musk scent	Mild scent glands	Mild / No flank musk

  3. Geographic Distribution and Colonial Origin

• Historical Introduction: Suncus murinus is not an indigenous species to Sri Lanka. It was almost certainly imported from mainland India centuries ago via trade cargo ships and coastal sea traffic.

• Present Distribution: It is widely distributed and common across major towns, ports, and commercial centers, primarily concentrated in the low-country wet and dry zones.

• Synanthropic Adaptation: The species relies heavily on human infrastructure, occupying drains, commercial storage units, residential kitchens, and outhouses.

4. Behavior, Territory Maintenance, and Pest Control Value

Nocturnal Foraging and Refuge

• Diurnal Inactivity: Retains a strictly nocturnal activity pattern, spending daylight hours hidden inside dark wall voids, under timber piles, behind kitchen appliances, or in ceiling crevices.

• Harmlessness to Humans: Despite its intimidating musk smell and sharp teeth, Suncus murinus is completely harmless to humans and does not bite unless directly handled or cornered.

Aggressive Territorial Suppression of Rodents

• Savage Predator Temperament: While non-aggressive toward humans, Suncus murinus exhibits extreme territorial savagery toward other small animals.

• Rodent Elimination: It actively attacks, kills, or drives away invasive mice (Mus musculus) and house rats (Rattus rattus) from its territory.

• Insectivorous Pest Control: Feeds voraciously on cockroaches, beetle larvae, venomous centipedes, and spiders during night hunts.

• Conservation & Economic Recommendation: Because it cleans homes of dangerous pests and drives away destructive gnawing rodents without damaging property, it is a highly beneficial animal that should never be harmed or killed.

5. Reproductive Biology and Development

The breeding strategy of Suncus murinus relies on protected nesting voids and rapid developmental milestones:

• Litter Size: Females give birth to 2 to 3 offspring per litter.

• Altricial Condition at Birth: Pups are born completely altricial—blind (eyes closed), hairless, and toothless.

• Nest Construction: The female constructs a spherical breeding nest using dry leaves, paper scraps, and shredded vegetative fiber tucked away in dark, secluded indoor crevices or outhouse corners.