[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Circus spilonotus | [authority] Kaup, 1847 | [UK] Eastern Marsh Harrier | [FR] Busard d’Orient | [DE] Mangroveweihe | [ES] Aguilucho lagunero oriental | [NL] Oosterse bruine kiekendief
The genus Circus is a cosmopolitan genus of about ten species. They are medium-sized, slender hawks, the female being considerably larger than the male. They are characterised by long, narrow, rounded tails, small beaks and long, slender legs. The most notable characteristic is the owl-like ruff of facial feathers that cover unusually large ear openings – an adaptation not for low-light hunting, but to locate prey by their rustling and squeaking in tall grasses.
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 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.
Eurasia : East
Its preferred habitat is open country including marshland, paddy fields and grassland.
The breeding season begins in April. The nest is made of sticks and built on the ground, usually in a reedbed. Four to seven eggs are laid which are incubated for 33 to 48 days. The young birds fledge after 35 to 40 days.
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.
Video Eastern Marsh Harrier
copyright: Keith Blomerley
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Mostly migratory; apparently sedentary in New Guinea. Populations from SE Siberia, Mongolia and NE China winter from Burma to S China and S to Malay Peninsula, Indochina, Sumatra, N Borneo and Philippines; in Japan, winters in C & S Honshu and Kyushu. each breeding areas during Apr and early May; leaves mainly Sept-Oct.