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Sep 25 2011

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Japanese Night Heron (Gorsachius goisagi)

Japanese Night Heron

[order] CICONIIFORMES | [family] Ardeidae | [latin] Gorsachius goisagi | [authority] Temminck, 1835 | [UK] Japanese Night Heron | [FR] Bihoreau goisagi | [DE] Rotscheitel-Reiher | [ES] Martinete japon | [NL] Japanse Kwak

Subspecies

Genus Species subspecies Region Range
Gorsachius goisagi EU Japan

Genus

Gorsachius is a genus of Old World night herons typically found near water in forested regions. These are medium-sized herons which are migratory in the colder parts of their ranges, but otherwise resident. They are the least known, most strictly nocturnal, smallest and overall rarest night herons. Three of the four species are found in East, South and South-east Asia, while the last species, the White-backed Night Heron, is found in sub-Saharan Africa. The Japanese and Malayan Night Herons resemble each other, being relatively short-billed and overall brown with a dark line from the throat to the upper belly. The larger White-eared and White-backed Night Herons are darker, with distinctive white markings on the face and neck in the former, and an entirely black head in the latter. While generally nocturnal and crepuscular, they have been recorded feeding during the day in clouded weather

Physical charateristics

Small, stocky heron with stout bill. Rufous-brown head and neck. Black streaks down foreneck and breast. Chestnut-brown upperparts and wing-coverts with fine black vermiculations. Juvenile has blackish crown, less rufous on head, more streaked neck and paler wing-coverts.


wingspan min.: 0 cm wingspan max.: 0 cm
size min.: 43 cm size max.: 47 cm
incubation min.: 0 days incubation max.: 0 days
fledging min.: 0 days fledging max.: 0 days
broods: 1   eggs min.: 3  
      eggs max.: 5  

Range

Eurasia : Japan. Gorsachius goisagi breeds in Japan, and there has been one report of breeding from Taiwan (China). It has been recorded in spring and summer in Russia (Primorye and Sakhalin) and South Korea, and is a passage migrant in coastal mainland China and Hong Kong (China), and also in Taiwan. The main wintering area appears to be in the Philippines, but it has also been recorded as a non-breeding visitor to Indonesia, and as a vagrant to Brunei and Palau.

Habitat

It breeds in heavily forested areas, including coniferous, broadleaved and degraded forest, on hills and on the lower slopes of mountains (up to 1,500 m), where there are watercourses and damp areas. It winters in dark, deeply shaded forest near water up to 2,400 m.

Reproduction

Little known, nestss in thick foliage 7-20 meter up in trees (conifers, cedars and also oaks). Nest is a thin stick platform, 3-4 eggs are laid which are incubated for about 17-20 days. The young fledge after about 5 weeks.

Feeding habits

It forages mainly in forest, but will use swamps, rice-fields and farmland and is mainly crepuscular. Earthworms are probably the principal food source, but land snails, crabs, ground and scarabid beetles are all present in its diet

Video Japanese Night Heron

httpv://www.youtube.com/watch?v=n5dlzxg5a4U

copyright: Desmond Allen


Conservation

This species has a very small, declining population, and therefore qualifies as Endangered. Declines are primarily a result of deforestation in its breeding and wintering ranges.
The main threat is deforestation in both its breeding and non-breeding ranges. The development of dense scrub undergrowth in forest and on abandoned farmland (following a change in traditional agricultural practices) is believed to reduce the suitability of these habitats for feeding. It has probably been hunted in many parts of its range. It declined rapidly on Miyake-jima in the Izu Islands, where it was formerly abundant, following the introduction of Siberian weasel Mustela sibirica in the early 1970s. Today nest predation by Corvids is an increasing threat as crow populations increase in urban and suburban areas.
Japanese Night Heron status Endangered

Migration

Some birds sedentary, but vast majority of population seems to migrate S in Sept/Oct, returning in early Apr. Record of exceptionally early migrant on Palawan (Philippines) on 5 Aug; following year recovered in S Honshu (Japan) on 28 Apr. Occasional records to N of breeding range on Hokkaido and Sado (N Japan), and also Sakhalin (off SE USSR). Sometimes diurnal during migration.

Distribution map

Japanese Night Heron distribution range map

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