The eastern marsh harrier (''Circus spilonotus'') is a bird of prey belonging to the marsh harrier group of harriers. It was previously considered to be conspecific with the western marsh harrier (''Circus aeruginosus'') but is now usually classified as a separate species. It has two

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

: ''C. s. spilonotus'' in eastern Asia and ''C. s. spilothorax'' (

Papuan harrier The Papuan harrier (''Circus spilothorax'') is a bird of prey native to New Guinea which belongs to the harrier genus ''Circus''. It was classified as a subspecies of the eastern marsh harrier (''Circus spilonotus'') of eastern Asia. It is thi ...

, perhaps a separate species) in New Guinea.

Description

It is 48 to 58 cm long with a wingspan of 113 to 137 cm; like most birds of prey, the female is usually larger than the male. The male's

plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...

is variable; typically the head, breast, back and wing-coverts are blackish with pale streaks. The rest of the wing is grey with black wingtips and a white front edge. The tail is grey, the rump is white and the underparts are mostly white. The female is dark brown with buff streaking on the head and underparts. The rump is often whitish and the tail has dark bars. Young birds are dark brown with buff on the head and a pale patch on the underwing. It is usually silent but has a mewing call which is most often uttered at roost sites.

Distribution and habitat

Eastern marsh harriers are generally migratory apart from the Papuan harrier which is sedentary. The breeding range covers north-east China, Mongolia and south-east Siberia (as far west as

Lake Baikal Lake Baikal (, russian: Oзеро Байкал, Ozero Baykal ); mn, Байгал нуур, Baigal nuur) is a rift lake in Russia. It is situated in southern Siberia, between the federal subjects of Irkutsk Oblast to the northwest and the Repu ...

) with small numbers in northern

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

(

Hokkaidō is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The la ...

and northern

Honshū , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separa ...

). There is some overlap with western marsh harrier around Lake Baikal and interbreeding has taken place. The wintering range includes southern China, Taiwan, Korea, southern Japan, northeast India, Bangladesh and Southeast Asia as far south as the Philippines, Borneo and

Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...

. Large numbers of birds migrate along the Chinese coast with thousands passing through sites like Beidaihe during the autumn. Its preferred habitat is open country including marshland,

paddy field A paddy field is a flooded field (agriculture), field of arable land used for growing Aquatic plant, semiaquatic crops, most notably rice and taro. It originates from the Neolithic rice-farming cultures of the Yangtze River basin in sout ...

s and grassland.

Diet and reproduction

While hunting it flies low over the ground with the wings held in a shallow V-shape. Its prey includes small mammals, birds and frogs. The

breeding season Seasonal breeders are animal species that successfully mate only during certain times of the year. These times of year allow for the optimization of survival of young due to factors such as ambient temperature, food and water availability, and cha ...

begins in April. The nest is made of sticks and built on the ground, usually in a

reedbed A reedbed or reed bed is a natural habitat found in floodplains, waterlogged depressions and estuaries. Reedbeds are part of a succession from young reeds colonising open water or wet ground through a gradation of increasingly dry ground. As ...

. Four to seven eggs are laid which are incubated for 33 to 48 days. The young birds

fledge Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable c ...

after 35 to 40 days.

References

*Mark A. Brazil (1991) ''The Birds of Japan'', Christopher Helm, London *Roger Clarke (1995) ''The Marsh Harrier'', Hamlyn, London. *John MacKinnon & Karen Phillipps (2000) ''A Field Guide to the Birds of China''. Oxford University Press. *Craig Robson (2002) ''A Field Guide to the Birds of South-East Asia''. New Holland, London. {{Authority control

eastern marsh harrier The eastern marsh harrier (''Circus spilonotus'') is a bird of prey belonging to the marsh harrier group of harriers. It was previously considered to be conspecific with the western marsh harrier (''Circus aeruginosus'') but is now usually classi ...

Birds of prey of Asia Birds of Manchuria Birds of Mongolia