North Sentinel Island is a small landmass of approximately 60 square kilometers nestled in the Bay of Bengal. Determining the exact composition of its fauna is an exercise in scientific inference, as the island is home to the Sentinelese, an uncontacted community who vigorously resist outside interference. The Indian government enforces a strict exclusion zone, meaning no scientific surveys have been conducted on the island’s interior. Consequently, most knowledge about the island’s animals is extrapolated from satellite imagery, limited coastal observations, and the known biodiversity of the wider Andaman and Nicobar chain.
Marine and Coastal Inhabitants
The waters immediately surrounding North Sentinel Island are relatively shallow and feature an extensive network of fringing coral reefs. This reef system is largely undisturbed by commercial fishing or pollution and is believed to be exceptionally healthy. The clear, nutrient-rich waters provide a habitat for fish, crustaceans, and mollusks, which serve as a primary food source for the island’s inhabitants.
Coastal observations confirm the presence of the massive coconut crab (Birgus latro), a species rare elsewhere but thriving in this protected environment. The Sentinelese forage for shellfish and crabs within the lagoon and reef zones, using small outrigger canoes. The sandy beaches also provide suitable nesting grounds for sea turtles, likely including the Green Sea Turtle or the Olive Ridley Sea Turtle.
These coastal areas also host a variety of sea birds. The healthy coral ecosystems act as nurseries for numerous fish and invertebrate species, supporting a dense and diverse population of coastal fauna.
Terrestrial Animals of the Interior
The forested interior, a dense tropical moist broadleaf forest, is the most mysterious area for zoological study. Based on limited sightings and analysis of the Sentinelese diet, the most reliably documented land mammal is the wild pig (Sus scrofa). Skulls of this animal have been found near temporary settlements, indicating that hunting the boar is a component of their subsistence strategy.
The island’s isolation makes it a potential refuge for reptiles and amphibians. Various species of snakes and lizards, including large monitor lizards, are likely present, as they are common across the Andaman archipelago. The small size of the island makes the existence of large mammals unlikely, but small, easily dispersed species such as rodents and bats are certainly present.
Avian Species and Migratory Birds
Bird life on North Sentinel Island is less constrained by the geographical barrier of water than land mammals. The island is situated along a major flyway for birds traversing the Bay of Bengal, making it an important stopover point for migratory species. Migrants such as various waders, plovers, and sandpipers use the island’s beaches and coastal mangroves for resting and feeding.
The resident bird population is likely composed of species endemic to the Andaman Islands. Examples likely found include the Andaman Wood Pigeon, the Nicobar Pigeon, and the Andaman Crake, which thrive in the dense forest and coastal habitats. Coastal raptors, such as the White-bellied Sea Eagle, also patrol the shorelines. The island’s unbroken forest canopy and pristine environment provide ideal nesting and foraging conditions.
The Role of Isolation in Biodiversity
The continuous, enforced isolation of North Sentinel Island has inadvertently created one of the world’s most protected natural areas for its fauna. It has been shielded from the detrimental effects of modern human development, such as logging, farming, and industrial pollution. This lack of external disturbance has allowed the ecosystem to evolve naturally, maintaining its ecological complexity and species richness.
The Indian government prohibits travel within a five-nautical-mile radius of the island. This exclusion zone, designed to protect the Sentinelese people, simultaneously protects the island’s biodiversity from invasive species, a primary threat to island ecosystems globally. The absence of introduced predators, like rats or feral cats, has preserved the integrity of the island’s native populations.