New Japanese Murrelet breeding site discovered

The discovery of a new breeding colony of Japanese Murrelet has come as a boost for the endangered species.

Several active nests were found on the 4-ha Hahakojima island, off the coast of Nagasaki, during visits by Japanese ornithologists in March and April 2023. The discovery has prompted speculation that other currently unknown colonies may be waiting to be found in Nagasaki Prefecture.

In March, ornithologists found several nocturnal gatherings of the alcid by torchlight off Hahakojima and Ozumo Rock (an adjacent islet). Searches were then carried out in April along the accessible cliff to confirm nesting – corpses, piles of feathers, destroyed eggs and predators were all noted.

A new Japanese Murrelet colony has been found in Nagasaki Prefecture (Christoph Moning).

New Japanese Murrelet colony

In total, some 129 Japanese Murrelets were counted at sea and 18 nests were discovered on the island. Furthermore, they also found 22 broken eggs and observed a Large-billed Crow with an egg in its beak.

The discovery of the new colony was documented in a recent report.

Further research will be needed to accurately assess the breeding population on this island and measures will be taken to attempt to reduce the impacts of corvid predation. The results should lead to research efforts on other potentially favourable islands – there are at least 971 islands and islets in Nagasaki Prefecture, most of which are uninhabited and similar to Hahakojima.

Rare seabird

Japanese Murrelet breeds locally off Japan and South Korea, and possibly also on the south-eastern tip of Russia. It winters at sea. It is one of the rarest alcids in the world, with a global population estimated at fewer than 10,000 adults that this declining due to human activities and predators (such as rodents and cats). It is considered Vulnerable by the International Union for Conservation of Nature (IUCN).

The largest known colony, on Biro Island in Miyazaki Prefecture, hosts 2,000 breeding pairs.