About 25-32 bird species, both resident and migratory, have been recorded from the island. Of these, the most famous is the
Narcondam hornbill (
Rhyticeros narcondami), a threatened
hornbill that is
endemic to the island. The closest living relative of the bird is the
Blyth's hornbill (
Rhyticeros plicatus). It has the smallest range of any Asian hornbill and only has a population of between 300 and 650 individuals, but still has a stable population. As Narcondam is a small volcanic island, not connected to any significant land mass, terrestrial
mammalian fauna is of low diversity. However, the
island flying fox (
Pteropus hypomelanus) and
Sikkim rat (
Rattus andamanensis) are the most common native mammals on this island. An unidentified small bat was also seen on a survey.
Introduced goats (
Capra aegagrus hircus) and
cats (
Felis catus) were formerly present on the island, threatening native fauna, but almost all of them have since been removed. There are several species of reptile on the island. The most common reptile on the island is the
spotted forest skink (
Sphenomorphus maculatus), which closely resembles populations of the species from
northeast India.
Tytler's skink (
Eutropis tytleri), a large
skink endemic to the Andamans, is also common on the island, with the Narcondam variants being slightly smaller than those on the main Andamans. The
Andaman Islands day gecko (
Phelsuma andamanensis),
Andaman bent-toed gecko (
Cyrtodactylus rubidus),
Andaman giant gecko (
Gekko verrauxi), and
Anderson's day gecko (
Cnemaspis andersonii), which are all
gecko species endemic to the Andaman-
Coco island chain, have also been found on Narcondam. The
Andaman water monitor (
Varanus salvator andamanensis) is the only large predator on the island and preys on the Narcondam hornbill, especially its young. The
paradise flying snake (
Chrysopelea ornata) has been reported from the island in past surveys. The
blue-lipped sea krait (
Laticauda laticaudata) is seen in the waters around Narcondam Island. The island was notified as a sanctuary to protect and monitor the Narcondam hornbill. ==Flora==