Bird Research News

Vol.7 No.9

2010.9.27.

Japanese Murrelet Kanmuri-umisuzume (Jpn) Synthliboramphus wumizusume
Morphology and classification
Classification: Charadriiformes Alcidae
Total length:220-265mm (60)Wing length: 113-132mm (163)
Culmen length: 13.8-17.8mm
Tarsus length: 23.2-27.8mm (152)

Tail length: 139-213g (214)
Tail length: 19-42mm (152)Bill depth: 6.7-8.6mm (124)

Quoted from Ono (1996). (Average, maximum-minimum, number of samples) of data
in Biroujima Isl. of Kadokawa Town, Miyazaki Pref. from 1993 to 1995.

Appearance:
Male and female are the same inplumage. The forehead, lore,
cheek, and flank are black. Theback is gray. The nape and underpart from chest to belly are white.
Breeding plumage has black crownfeathers 3-5cm long. AncientMurrelets S. antiquus, which are
Photo 1. Japanese Murrelets.
closely related to Japanese Murre[Photo by Yoshiharu Suzuki]
lets, on the other hand, lack thesecrown feathers. The bills of Japanese Murrelets are bluish gray, but
those of Ancient Murrelets look white, shorter and somewhat
thick. Both species have a white throat in breeding plumage, butthis white part extends into the neck in Ancient Murrelts, but not inJapanese Murrelets. In the non-breeding seasons, the crown feathers of Japanese Murrelets become shorter and the area around aneye is white with the upperparts pale gray.

Vocalization:
They call like "Chui, Chui, Chooi …" or "Pidju, Pidju ...". and“Chieet".

Distribution and Habitat
Distribution:
Japanese Murrelets are
distributed from Taiwan,and Ishigakijima and Iriomotejima Islands of Okinawa (24° N) to the Nemuro
Peninsula, and Shikotan andSakhalin Islands (50° N),
but they are concentrated in
the northwestern part of theSea of Japan and southern
South Korea.

Life history
12345breeding season

678910

11 12

non-breeding season

Breeding system:
Japanese Murrelets are basically monogamous. They start to appear in the sea surrounding their breeding grounds in late January
or February in the Izu Islands. The first age of breeding is notknown. Mating is poorly known, but the observations of two birds
in a nest with no eggs (Nakamura & Ono 1997) and apparent mating in a nest (Ono 1993) suggest that copulation may occur in anest.

Nest:
Japanese Murrelets nest in a gap in a rock, a crack in a cliff, at theroot of grass such as sedge, in a ground depression and a gap in a
man-made structure such as the stone wall of a lighthouse. They
not only lay eggs in these sites without building a nest but also diga burrow in the ground or use an old nest of other bird species(Higuchi 1979).

Clutch size, and size and color of eggs:

Photo 2. Japanese Murrelets swim
against a background of Onoharajima Island, Izu. [Photo by Yoshiharu Suzuki]

Habitat:In the breeding season, they stay in the waters around the breeding
grounds, but they spend the non-breeding season far away from thebreeding grounds. They range in the waters with surface temperatures between 8 and 22°C throughout the year (Gaston & Jones
1998). Little is known about their ecology of the non-breeding
season.

Breeding habitat:
Japanese Murrelets breed only on the reefs and the remote islandsof Japan and southern South Korea. Six of seven species of Alcidae breed in Hokkaido and a part of Tohoku region, but JapaneseMurrelets are the only murrelet species that breed in the temperatewaters from Torishima of the Izu Islands (30° N) to Nanatsujima
Island, Ishikawa Prefecture (37° N). They build nests on reefs orcliffs free from waves, sedge grasslands, forest floors
and gaps in artificial structures, such as the stone wall

24of a lighthouse on a remote island.
The largest breeding colony of Japan is located on Biroujima Island, Miyazaki Prefecture, which accommodates approximately
3000 birds. It is followed by the Izu Islands that hold about 1000
birds. They also breed on Koyajima of Chikuzen Okinoshima Islands, Fukuoka Pref., Mimianajima Island, Mie Pref., KoushimaIsland, Kochi Pref. and other islands. They are estimated to be
5000 to 6000 birds (Ono 1995, 1996). In the Izu Islands, the breeding is confirmed in a total of nine locations, such as Tadanaejima
and Onbasejima of Kozu Island, Onoharajima of Miyake Islandand Hanshima of Niijima Island (Carter et al. 2002). In addition,family groups have been observed recently in the western area ofthe Inland Sea (Setouchi region), which suggests the breeding
possibility (Iida 2010).
Outside of Japan, Japanese Murrelets were recorded to breed on
Gukholdo Islands, southern South Korea (Won 1984), and a corpseof a juvenile Japanese Murrelet was found in the Bay of Peter theGreat, Russia in July 1984, which suggests a possibility that asmall number of them breed in this area (Nazarov & Shibaev
1987).

The clutch size of Japanese Murrelets is 1-2 eggs. Major axis ofthe egg is 54.1 ± 1.5mm by 34.7 ± 1.0mm, with weight of 35.6 ±
2.6g (Ono 1996). The egg accounts for as much as 22% of female
body weight. The eggs have reddish dark brown, blackish brownand gray-blue speckles on an off-white, pale red-brown, gray-blueand light brown grounds.

Incubation and nestling periods, and hatching rate:
The egg-laying begins from mid to late March on Biroujima Island. Two eggs are usually laid and the incubation starts when thefirst egg is laid, but the first egg is incubated only during the night
until the second egg is laid, when male and female begin to taketurns incubating eggs continuously. After a month incubation thetwo eggs hatch at almost the same time in late April or early May(Ono 1996). Hatching rate was reported to be about 60% from
Koyajima Island, Fukuoka Prefecture. (the Research Division ofthe Wild Bird Society of Kitakyushu 1978).
The chicks leave the nest for the sea during the night one or twodays after hatching, guided by the call of the parent birds (Ono2010). It is not until they are out on the sea that parent birds feed
their chicks, but the rearing period is not known.
The breeding starts later on the Izu Islands, Tokyo than Biroujima
Island. The chicks hatch from early to mid May, and the family,
thereafter, move elsewhere from the waters around the breedingBird Research News

Vol.7 No.9

2010.9.15.

© Japan Bird Research Association
Sumiyoshi 1-29-9, Fuchu, Tokyo, Japangrounds. It is poorly known where Japanese Murrelets spend thenon-breeding. However, the information collected through theInternet (the Wild Bird Society of Japan 2010) and by-catch data
(Piatt & Gould 1994) confirmed them off the coasts of Sanriku ofTohoku region, as well as the eastern and southeastern Hokkaido,
northern Japan. This suggests that they moved north from the Izu
Islands or more southern areas.

Diet and foraging behavior
Japanese Murrelets dive into the sea or forage on the surface at thepoint where two ocean currents meet individually or in a smallflock. They were observed to capture small fish such as sardines
and banded blue-sprat. The stomach content examination confirmed small fish, small shellfish and crustacean larvae (Moyer1957). There are no other information or data about their feeding
habits and foraging behavior.

Topics of ecology, behavior and conservation● Offshore distribution of Japanese Murrelets in thebreeding season
Cumulative number of observations /Total number of observations (%)

Data on the offshore
100.0
distribution of Japanese
80.0
Murrelets around thebreeding sites have been
60.0
collected gradually by
40.0
the Wild Bird Society ofJapan. On Onoharajima
20.0
Island of Miyakejima
0.0Island, for instance,
1km 2km 3km 4km 5km 6km 7km 8km 9km
about 80% of JapaneseDistance from Onoharajima Island (breeding ground)
Murrelets observed foraged within 6km of their Fig. 1. Distribution of Japanese Murrelets
in the area around the breeding ground.
breeding ground in thebreeding season of 2009
(Fig.1). The density of the murrelets was higher in the area lessthan 4 km of the breeding ground.
We carried out a simultaneous survey of this species on five fishing vessels off the Izu Islands (Miyakejima, Mikurjimaa, Kozushima, Niijima Islands, and Mikomotojima Island of the Izu Peninsula), and counted at least 441 birds in April 2010. Considering that
we failed to detect a fairly large number of them, measures such asincreasing survey courses need to be taken to improve detection
accuracy in the future.

● Contributory factors to the reduction of Japanese
Murrelets
Censuses from a passenger liner that operates on a fixed schedule
indicated that Japanese Murrelets declined in the waters between
Niijima and Oshima Islands of the Izu Islands (Mochizuki andUeta 1996). It was also reported that they ceased to breed on
Shikinejima and Kozushima Islands (Carter et al. 2002).
The decline of this species are attributed to the predation of eggs,
chicks and adult birds by crows attracted to the chum or foodscraps left by anglers who landed on the breeding islands. In addition, it was reported that brown rats catastrophically damaged thebreeding colony on Koyajima Island, Fukuoka Prefecture(Takeishi 1987). The entry of people to the breeding grounds leads
to increasing the chances that the murrelets desert their nests andrats intrude there.
Entanglement in fishing nets is also responsible for the population
decline. Japanese Murrelets were reported to be entangled in gillnets of squids in the area at 40-42° N and 143-146° E from August

バードリサーチ生態図鑑
to November (Piatt & Gould 1994). The entanglement in gill netsof flying fish was also reported from the Izu Islands (Ono 1997).
In addition, mortalities due to oil pollution were reported (Sato1999, Committee of the Oil Pollution Damage on Seabird 2001).
In order to conserve this species, it is necessary to control predators in the breeding grounds including thorough management offood scraps attracting them, to arouse the public awareness and to
take measures to reduce by-catch in conjunction with the population monitoring.

Literature
Committee of the Oil Pollution Damage on Seabird ed. 2001. Survey of seabird
mortality by oil pollution. The report of the damage investigation of Nakhodka
oil accident on seabirds. 195-218. Committee of the Oil Pollution Damage onSeabirds. Tokyo. [J].
Gaston A.J. & Jones I.L. 1998. The Auks. Oxford University Press. New YorkWon P. 1984. Gukholdo Islands breeding grounds of seabirds (Japanese Murrelet,
Streaked Shearwater and Swinhoe's Storm Petrel). Natural Treasure Birds ofKorea. pp. 129-131. (In Korean)
Carter H.R., Ono K., Fries J.N., Hasegawa H., Ueta M., Higuchi H., Moyer J.T.,
Ochikubo Chan L.K., de Forest L.N., Hasegawa M. & van Vliet G.B. 2002.
Status and Conservation of the Japanese Murrelet (Synthliboramphus wumizusume) in the Izu Islands, Japan. J. Yamashina Inst. Ornithol. 33: 61-87.
Higuchi Y. 1979. Distribution and breeding ecology of the Japanese Murrelet.
Kaiyo to Seibutsu 3: 20-24. [J]Iida T. 2010. First confirmation of multiple family groups of Japanese Murrelet in
the western Setouchi Sea. Jpn. J. Ornithol. 59: 73-75.[J+E]
Research Division of the Wild Bird Society of Kitakyushu. 1978. The Survey on
man-related damage on the breeding ground of Japanese Murrelets and Swinhoe's Storm Petrels of Koyashima of Chikuzen Okinoshima. Vol 3. Summary.
Wild Bird Society of Kitakyushu, Kitakyushu. [J]Mochizuki H. & Ueta M. 1996. Decrease in the population of Japanese Murrelets inthe Izu Islands. Strix 14: 173-176. [J+E]
Moyer J.T. 1957. The Birds of Miyake Jima, Japan. Auk 74: 215-228.
Nakamura Y. & Ono K. 1997. On the Japanese Murrelet in Biroujima of Kadokawa
town. Miyazaki Prefectural Museum Bulletin 20: 25-40. [J+E]
Nakamura Y., Sueyoshi T. & Fukushima H. 2010. The fledglings of Japanese
Murrelets. Miyazaki Prefectural Museum Bulletin. 30:1-9. [J+E]
Nazarov Y.N. & Shibaev Y.V. 1987. Synthliboramphus wumizusume breeds on thenorth-west coast of the Sea of Japan. Distribution and Biology of Seabirds of theFar East. 87-88.
Wild Bird Society of Japan. 2010. 15 Letter from the Kuroshio (747): 46. [J]
Ono K. 1993. Breeding ecology and offshore distribution of Japanese Murrelets
around the Izu Islands. Toho University Faculty of Science Master's thesis.
Chiba. 49pp. [J]
Ono K. ed. 1995. Current status and protection of rare murrelet species. Japan alcid
study group. Funabashi. [J]
Ono K. 1996. Basic data about the rare wild aquatic organisms in Japan (III). JapanFisheries Resource Conservation Association. 7. Japanese Murrelet. 514-519. [J]
Ono K. 1997. Human symbiosis with sea birds learning from Japanese Murrelet.
Yacho. (603): 12-13. [J]
Ono K. 2010. Japanese Murrelets. Encyclopedia of wildlife protection. 490-493. [J]Piatt. J.F. & Gould P.J. 1994. Postbreeding dispersal and drift-net mortality ofendangered Japanese Murrelets. Auk 111:953-961.
Sato H. 1999. Oil pollution damage of seabirds in the Sea of Japan that occurred in
January 1986. J. Yamashina Inst. Ornithol. 31:134-141. [J+E]
Takeishi M. 1987. On the mass mortality of Japanese Murrelets in Koyajima ofFukuoka Pref. Bulletin of Kitakyushu Museum of Natural History 7: 121-131.

AuthorYutaka YAMAMOTO Wild Bird Society of JapanI started working in the Wild Bird Society of Japan in 1991. After working as a ranger in nature
centers in Hiroshima and Miyakejima Island, I am
assigned to the Nature Conservation Division
since 2008. My encounter with Japanese Murrelets
is when participating in the offshore survey in oneof the breeding grounds of Onoharajima ofMiyakejim Island in 1994. I would like to conserve this species firstly by understanding the current status of theirbreeding grounds in the Izu Islands. We received grants for the offshore survey from Nippon Foundation and the Student Birdathon
Committee. I would like to thank them in this opportunity. y-yamamoto@wbsj.org

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