Bird Research News

Vol.8 No.9

2011.9.28.

Japanese Green Pigeon
Morphology and classification
Classification: Columbiformes Columbidae
Total length: 315-348mm
Wing length: ♂ 183-196mm ♀ 177-187mm ♂ Juv. 172-186mm
Tail length:♂ 109-133mm ♀ 103-123mm ♂ Juv. 100-105mm
Culmen length: Ad. 18-21mm♂ Juv. 20mm
Tarsus length: Ad. 24-28mm♂ Juv. 20-27mm
Weight:Ad. 217-300g
Total length after Enomoto (1941), other measurements of adults after Kiyosu (1978),and those of juveniles (age approximately 1.5-2 months) after Komatan (2004b).

Aobato (Jpn) Treron sieboldii
142°13'E). This species ranges to the northernmost region among
the genus Treron (Nakamura 1980). The subspecies T. s. sieboldii
is assumed to be endemic to Japan (Kiyosu 1978, Gibbs 2001,Komatan 2004a).

Habitat:Japanese Green Pigeons are forest-dwellers from hills to moun1 2out 3to an
4 open5 6place,
7 but
8 they9 10
12月
tains. They rarely comehave11a habit
繁殖期
of visiting a coastal areainaflocktodrink
seawater
from
early
換羽期
非繁殖期
（つがい形成〜家族期）
summer to autumn. They spend most of the breeding period inbroad-leaved deciduous forests south of Honshu, but they are lessabundant in Hokkaido, northern Japan (Fujimaki 1999).

Appearance:

Life history

The Japanese Green Pigeons are roughly green all over with somesexual dimorphism in plumage coloration. They have pink feet andsoft light blue bills. The iris is two-toned with the outer red ringand blue inner ring (Photo 1). Males have reddish purple patch on
the small and middle wing coverts, greenish brown patch on thegreater wing coverts and grayish green long and broad shaft-stripeson the undertail covert. They are dark green from the crown to theback and pale yellowish white on the abdomen. They are generally
yellowish green or yellow on the forehead and from the throat tothe chest, but these parts are sometimes tinged with orange. The
females have no reddish purple patch on the wing coverts. Also thegreen color of the forehead and throat to the chest is deeper infemales than in males. A dead male had 4,715 feathers including
14 rectrices (Komatan 2004a).

1

Photo 1. Adult
male (left) andfemale (right).

Juveniles have buff-colored tips of the greater wing coverts andsecondary flight feathers, which stand out and look like 2-3 whitebands (Photo. 2). Since juvenile birds are smaller, with narrower
secondary remiges and shorter rectrices than adults, they are distinguishable while flying at Terugasaki Point, Kanagawa Prefecture where they come to drink seawater. About a month after fledging,male juveniles develop reddish purple
patches on the wing coverts, whichlook like 2-3 partial bands or flecks. At
this time, they become almost the same
size in bill and body as adults, but the Photo 2. Juvenile male.
bill color is mostly pink.

Vocalization:
Japanese Green Pigeons frequently sing in the breeding period like"Oh-, aoh-, Ah-oah-, Oh-aoah-" with stress laying on "a" part,which sounds like a bamboo flute or the yodelling in falsetto. The
song consists of a high and a low tones. They also mutter rapidly"Popopopo", "Poh-poppoppoppo" or "Kokokokokoko" (Komatan
2003a). The song goes "Oh-oh-go-Att-oh-, oh-, oh-, oah-o, oah-o,ah-oah-o, AoAh-, ah-oao, oaoh-, oh- " in the study site of Kanawa
Pref.. Hearing it in the distance, however, you can hardly catch theprelude of "Oh-oh-go-Att-oh-".

Distribution and Habitat
Distribution:
Japanese Green Pigeons are distributed in the Far East such as thesouthern Sakhalin, Kunashirito in the Kuril Islands, Japan, southeastern China, Taiwan and northern Vietnam. They are also recorded in the subtropical islands such as the Ryukyu Islands, the Izu
islands and the oceanic Ogasawara Islands (27°4' N,4♪ http://www.bird-research.jp/1_shiryo/koe/aobato_0905_hyogo_kaji.mp3
Kyoko Kajimoto

2345 6 7 8 9
courting breeding period
period

10 11 12non-breeding
periodBreeding system:
Japanese Green Pigeons breed from mid-May to mid-September in
the Tanzawa mountains, Kanagawa Pref., central Japan. They canbreed twice in one breeding season. They arrive at the breeding
grounds in mid-April and move about in flocks until early May.
They call like "Popopopo", bobbing their tails and shaking theirheads, which is assumed to be their courtship behavior. This"Popopopo" call is heard in May and in late June, which suggeststheir two breeding attempts (Komatan 2003a).

Nest:
A nest of Japanese Green Pigeons wasfound in the fork of the branch of a dog
hornbeam at a height of 12m in the Tanzawa Mountains. The nest tree was 18m inheight and 28cm in diameter at breast
height. The nest was built on a branchwith hardy kiwi (Actinidia arguta) vine
twined around it (Photo. 3). The nest wasplate-shaped and about 25cm in diameterwith fine twigs piled on the bottom(Komatan 2003a). Only a few nests havebeen discovered in Japan due to the diffiPhoto 3. Nest and nest
culty in finding them.
tree.

Egg:
The clutch size is two eggs. The egg is milky white with no flecks.
The size is 29.0-34.5mm by 21.0-27.4mm (Kiyosu 1978).

Incubation and nestling periods:
The records from the Tanzawa Mountains showed that the incubation and nestling periods were about 15 days each. Both males andfemales were engaged in the incubation and chick-rearing. Males
usually incubated during the day, while females probably at night
because they were frequently in the nest in the early morning. Themale and female exchange the incubation duty without a break, buton the day just before fledging both parents had left the nest up to30 min.
The nestlings and juveniles receive the unique piegeon milk by
poking their heads into the parents' mouth. Both male and female
parents produce and feed pigeon milk to their young. The observation records from Terugasaki Point suggest that it is not until 25
days or more after fledging that the juveniles come to the coast todrink seawater.

Migration:
Japanese Green Pigeons breed throughout Japan up to Kunashiritoof southern Kuril Islands, but the population of northern areas
mostly moves south in winter and the wintering record is rare in
Hokkaido (Komatan 2004a).

Bird Research News

Vol.8 No.9

2011.9.28.

© Japan Bird Research Association
Sumiyoshi 1-29-9, Fuchu, Tokyo, Japan

Diet and foraging behavior
Japanese Green Pigeons are frugivorous and feed primarily in the tree
canopy, but in winter, may frequently forage for acorns on the ground as
well as on trees (Photo. 4). In thebreeding season they chiefly eat
berries, but also feed off the sprouts,buds and flowers from trees before
Photo 4. A Japanese Green
they bear fruit. They are a seed disPigeon eating acorns onperser for berry-bearing plants bethe ground in the noncause the pigeons do not digest theirbreeding period (Kyoto
seeds, but are a consumer for oaks
Imperial Palace Park).
because they digest acorns (Sasaki
1986, Komatan 1996, 2004a, and 2005).

Topics of ecology, behavior and conservation● Behavior of drinking seawater

バードリサーチ生態図鑑
habitat destruction, we must prevent them from further declines.
The conservation of such pigeons would only be achieved by protecting not only their breeding sites, but also foraging and roostingsites as well as the seawater drinking spots, preferably to conserve
one large area including these three habitats. In Kanagawa Pref., theconservation of the three major habitats should include such areas as
the breeding forest of the Tanzawa Mountains, the seawater drinking spot at Terugasaki Point, and the foraging and roosting sites in
the western hilly region of Oiso and Hiratsuka located between thesea and the forests. In addition, it is known that they move to western Japan and winter in shrines and parks of urban areas, but nostudies have been conducted about the wintering sites of JapaneseGreen Pigeons in Japan except for Miyazaki Pref., Kyoto Pref. andOiso, Kanagawa Pref.. There is a need, therefore, for more researchto accelerate efforts to conserve the wintering grounds of this species (Komatan 2003b, 2005, 2007).

Literature
Enomoto Y. 1941. Body size of Japanese birds. Osaka Chapter of Wild-Bird Society ofJapan. Osaka. [J]Fujimaki Y. 1999. The distribution status of Turtledove and Japanese Green Pigeon incentral and southeastern Hokkaido. Strix 17:15-23. [J+E]
Gibbs D. Barnes E. & Cox J. 2001. Pigeons and Doves. A Guide to the Pigeons andDoves of the World. 454-455. Pica Press, UK.
Kawaguchi M. 1937. Ecological note on Japanese birds. pp.230-247. Sorin-shobo,
Tokyo. [J]Kiyosu Y. 1978. Comprehensive Guide to Japanese Birds. New edition with supplements. Kodansha. Tokyo. [J]Komatan. 1996. Seeds found in feces of Japanese Green Pigeon Treron sieboldii BINOS
3:1-8. [J+E]
Komatan. 2003a. Breeding behavior of the Japanese Green Pigeon Treron sieboldii atDoudaira in the Tanzawa Mountains, Kanagawa Prefecture, Japan. BINOS 10:1-17.
[J+E]
Komatan. 2003b. Observation records of the Japanese Green Pigeon Treron sieboldii
wintering at Mushikubo area of Ohiso town, Kanagawa Prefecture, Japan. BINOS
10:99-108. [J+E]
Komatan. 2004a. Mystery of the Japanese Green Pigeon. HSK, Saitama. [J]Komatan. 2004b. Observation of juvenile Japanese Green Pigeon at Terugasaki Beach,Oiso. BINOS 11:1-6. [J+E]
Komatan. 2005. Observation records of Japanese Green Pigeon Treron sieboldii wintering at National Garden 'Kyoto Gyoen' of Kamigyo-Ku, Kyoto, Japan. BINOS 12:735. [J+E]
Komatan. 2007. Japanese Green Pigeon Roosting in Woods Near Terugasaki Beach.
BINOS 14:1-13. [J+E]
Komatan & Kato C. 2007.Comparison of Digestive System and Observation Records 2Japanese Green Pigeon Cared for at the Natural Environment Conservation Center ofKanagawa which were Provided with Fruit and Salt Water. BINOS 14:15-30. [J+E]
Sasaki I. 1986. Japanese Green Pigeons. Self-publication, Sapporo. [J]Nakamura K. 1980. Avifauna of Kanagawa. Kanagawa Chapter of Wild Bird Society ofJapan (ed.). Yurindo, Yokohama. [J]Yamada T. Maekawa F. Egami F. Yasugi R. Koseki H. Furutani M. and Hidaka T. eds.
1991. Iwanami Biology Dictionary the third edition. Iwanami-shoten, Tokyo. [J]Wada, K. 1926. Aomori Prefecture Library Complete Volume Notes on Japanese Animals. Kodansha, Tokyo. [J]In the breeding season, Japanese Green Pigeons are wellknown for
drinking seawater in the coasts of Hariusu, Hokkaido, Terugasaki
Point, Kanagawa Pref. and Lake Hamana, Shizuoka Pref.. They arealso observed to drink mineral spring water and hot spring water in
Biei Town, Hokkaido, Tamagawa, Akita Pref., Ueno Village, Gumma Pref. and Ono City, Fukui Pref.. They can drink water keeping
the nostrils under the water as in other pigeons and flamingoes.
There is no record of drinking seawater during the non-breeding
season.
Since they are very cautious during the breeding period, it is very
hard to observe them in a forest. In the coast, especially Terugasaki
Point, however, they sometimes land close to the people who areindifferent to them. Nevertheless they do not relax their vigilancebecause some of the birds of a flock are always on the alert. Therefore, we should exercise great moderation when we observe andphotograph them.
It is convincing to assume that Japanese Green Pigeons drink salty
water to maintain the osmotic pressure of the body fluid throughkeeping a balance between sodium and potassium in the body
(Yamada et. al. 1991). It is explained that Japanese Green Pigeons
ingest sodium by drinking seawater because their diet consists primarily of fruits containing a large quantity of potassium. However,this theory has not been physiologically demonstrated yet (Komatan& Kato 2007). Every year at Terugasaki Point, some of the pigeonsfall victim to high waves, which suggests that seawater drinking is aphysiologically indispensable behavior for the pigeons at the risk of
their life.

Author● Relation with people and history as a game birdKomatan

Japanese Green Pigeons had been historically hunted indiscriminately for food. They were on a game bird list in Japan until 1947,
when the law was revised. This was because they were delicious andeasy to shoot as well as they were considerably abundant then.
"Japanese Green Pigeons are not easily shot because they are cautious when perched in a tree alone and never return when you missthem. But they tend to relax their vigilance when they move aroundin a flock (Kawaguchi 1937)." "Since (Japanese Green Pigeons) aredelicious, they are sold in many shops in autumn in the Chugoku
and Kansai regions, western Japan (Wada 1926)." These records
show that they were hunted and sold on the market as food. It
should be noted that Japanese Green Pigeons were hunted in large
number in the past and that they were concerned to go extinct as in
the case of Passenger Pigeons of North America (Sasaki 1986, Komatan 2004a). Japanese Green Pigeons are currently designated as"LC"(Least Concern) in the red list of IUCN. Since it is assumed
that they have drastically declined due to indiscriminate hunting andHideki OSAKA, Noriyoshi KANEKO,Tsunemi SAITO, and Yutaka TABATA

Komatan is "an amateur bird-watching group which admires flowers andinsects as well as birds in Hiratsuka and Oiso, Kanagawa Prefecture". We
are nice to beginners and engaged in the observation, study and conservation of nature, enjoying anything related to nature with due moderation.
Our group has no regulation, fee, or representative. The monthly birdwatching walk started in the name of "Heights bird watching" in August
1983. The walk got a nickname of "Koma tanchokai" at the 6th time,
which was abbreviated to the current name of "Komatan" at the 7th walk.
We celebrated the 336th walk in August 2011. We have published tenscientific papers and two books in these years.

OSAKASAITOKANEKOTABATA5