Japanese Murrelet Synthliboramphus wumizusume Scientific name definitions

Kanmuri umisuzume, more widely known as the Japanese Murrelet, is a strikingly patterned bird that breeds only on islands off the coast of southern Japan and South Korea. Its Japanese name translates to "Crested Sea-Sparrow" in English, with the closely related Ancient Murrelet (Synthliboramphus antiquus), simply known as umisuzume, or "Sea-Sparrow." Kanmuri can refer to any one of a number of caps given to Japanese boys at their coming of age ceremony, which dates back as far 710-794 AD (1 Batkalova, K., and A. Galiev (2016). Rites of Passage in Japanese Traditional Culture. The International Conference on Japan & Japan Studies 2016. Close ), with the shape of the crest indicating one's social class. In the case of the Japanese Murrelet, Kanmuri is said to refer to a warrior's cap, with such plumes adorning Samurai helmets as long ago as the 4th or 5th century AD (2 Kure, M. (2014). Samurai: An Illustrated History. Tuttle Publishing. North Clarendon, VT, USA. Close ). Hence, this cute wee bird could just as well be called Samurai Sea-Sparrow.

The Japanese Murrelet, with an overall length of 24–26 cm and mass of approximately 163 gm, is about the size of a Northern Bobwhite (Colinus virginianus). In breeding (Definitive Alternate) plumage, it is mostly pale bluish-gray above and white below, with a band of black running along the side separating the two. The head is black, but upon that head sits a long black-and-white crest, with the white plumes for which the bird is named (in Japanese) lying laterally. Basic plumage is more subdued, with the throat turning white, the sides becoming gray, and the crest reduced or absent.

Like the Ancient Murrelet, the Japanese Murrelet has a relatively small bill, specialized neither for fish nor plankton, and an overall structure between that of specialized wing-propelled divers such as murres and that of less specialized auklets. In keeping with these traits, it lives on a diet of small fish and large zooplankton, especially euphausiid crustacea (a.k.a., krill), which are captured in shallow V-shaped dives. Throughout the year it forages mostly over the continental shelf, generally closer to shore during the breeding season and more broadly at other times of year, especially favoring locations where currents converge to cause upwellings, with their attendant abundance of prey.

Nesting islands tend to be steep and rocky, with nests most often placed 15–60 m above the sea in the crevices and cracks of cliffs, though at some locations burrows in dense grass or soil are used. Two eggs are laid, typically between late February and the end of March, with the chicks hatching just over a month thereafter. As is typical of Synthliboramphus murrelets, the precocious downy young are not fed in the nest, but are called to the sea by their parents a night or two after hatching, and then led swiftly away from the breeding colony.

The Japanese Murrelet is considered Vulnerable, with a population of approximately 9,000–13,000 individuals and 2,800–4,100 breeding pairs that occupy 25 known colonies. Its population appears stable, but may be declining due to heavy tolls inflicted by native crows (Corvus sp.), introduced rats (Rattus sp.) and the squid fishing industry, which probably kills approximately 1–10% of the total population annually. The future of the Japanese Murrelet can be ensured only by removing rats from nesting islands, limiting the attractiveness of those islands to crows (by controlling garbage and offal left by fisherman), and adjustments in fishing methods (which would also benefit a host of additional bird species).