Japanese Murrelet

The Japanese murrelet, also known as the crested murrelet (Synthliboramphus wumizusume), is a diminutive seabird belonging to the auk family. It is characterized by its blackish and bluish-grey upperparts, white throat and underparts, and a distinctive black crest during the breeding season. The bird's bill is bluish-grey, legs and feet are yellowish-grey, and the iris is dark brown. Adults typically measure 24–26 cm in length with a wingspan of 43 cm and weigh between 164–183 grams.

Identification Tips

In identifying the Japanese murrelet, look for the white stripe extending from the top of each eye to the nape, which is more visible outside the winter season. The summer crest of black feathers, which can be 3–5 cm in length, is a key distinguishing feature from the similar Ancient murrelet, although this crest is absent in winter. Juveniles resemble winter adults but have somewhat browner head and upperparts.

Habitat

This species nests in rocky crevices and hollows, gaps between stone piles, and among grasses on uninhabited islands. It prefers boreo-cool and temperate-subtropical waters of the northwest Pacific for its habitat.

Distribution

The Japanese murrelet breeds along the rocky coasts and islets of Japan, from Nanatsujima in Ishikawa Prefecture to Tori-shima in the Izu Islands. After breeding, it disperses along Honshū and Kyūshū and may be found as far north as Sakhalin and as far south as Taiwan.

Behaviour

The Japanese murrelet's behaviour includes a shared incubation duty by both parents for the typically two eggs laid. The precocial chicks leave the nest on the second night after hatching, accompanied by their parents.

Song & Calls

The bird's vocal repertoire includes a quiet "ch-ch-chi-chi" call, a "peee-p-p-p" in flight, and a "jee-jujjujju" among others. At the nest, sounds such as "jijiji-pipewpipewkukukuku", "gugguwa-gugugu", and "jukkukuwa-kuwakuwakuwa" can be heard.

Breeding

Breeding occurs from late March to early April, with egg-laying happening a week apart. Incubation lasts about a month and is nearly equally divided between the parents.

Diet and Feeding

The diet of the Japanese murrelet primarily consists of krill, planktonic crustaceans, crangonid shrimps, and small pelagic fish such as Pacific herring, sculpin, smelt, sand eels, and sandlances.

Conservation status

The Japanese murrelet is classified as Vulnerable on the IUCN Red List due to its small and declining population, estimated at 2,500–10,000 individuals. Threats include by-catch in commercial fishing operations, predation by invasive species, and habitat disturbance. It is legally protected in Japan and listed on Appendix I of the Convention on the Conservation of Migratory Species of Wild Animals.