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Gorsachius goisagi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES PELECANIFORMES ARDEIDAE

Scientific Name: Gorsachius goisagi
Species Authority: (Temminck, 1835)
Common Name(s):
English Japanese Night-heron, Japanese Night Heron, Japanese Night-Heron

Assessment Information [top]

Red List Category & Criteria: Endangered C2a(i) ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Allen, D., He, F., Kawakami, K. & Kominami, Y.
Facilitator/Compiler(s): Benstead, P., Bird, J., Chan, S., Crosby, M., Khwaja, N., Peet, N., Taylor, J.
Justification:
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.

Geographic Range [top]

Range Description: Gorsachius goisagi breeds in Japan. There has been one report of breeding from Taiwan (China), and recent work has discovered a breeding site at Jeju Island, South Korea (Oh et al. 2010). It has also been recorded in spring and summer in Russia (Primorye and Sakhalin), 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. Improved awareness of the identification criteria for immatures of this species has led to a marked increase in records from the Philippines (D. Allen in litt. 2012). It was apparently locally common in Japan until the 1970s, but by the 1980s and 1990s had disappeared from many of its former breeding sites. There have apparently been just two records from mainland China since the early 1960s, one of two sightings at Wuyuan in Jiangxi Province in April 2006 and a taxidermy specimen noted in Haiyan county in Zhejiang province in February 2010 and apparently purchased in Haining city in April 1998 (He Fenqi in litt. 2007, 2012). The relative paucity of recent records suggested that the population numbered fewer than 1,000 mature individuals, but recent work in Japan and increasing numbers of records from the Philippines imply that this may have been overly pessimistic. Hence, the true figure may lie within the band 1,000-2,499 individuals. However, this may still be an underestimate (K. Kawakami in litt. 2012).

Countries:
Native:
China; Hong Kong; Indonesia; Japan; Korea, Republic of; Philippines; Russian Federation; Taiwan, Province of China
Vagrant:
Brunei Darussalam; Palau; Viet Nam
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Recent work in Japan suggests the previous assertion that the global population comprises fewer than 1,000 individuals may have been overly pessimistic (although Brazil 2009 estimated fewer than 100 breeding pairs, fewer than 50 individuals on migration and fewer than 50 wintering individuals in Japan). Hence, the true figure probably lies within the band 1,000-2,499 individuals. This equates to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: It breeds in heavily forested areas, including coniferous, broadleaved and degraded forest, on hills and 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. It forages mainly in forest, but will use swamps, rice-fields and farmland and is mainly crepuscular. Breeding has been recorded from April to July (Kawana 2006). Earthworms are probably the principal food source, but land snails, cicadas, crabs, and ground and scarabid beetles are all present in its diet (Kawakami et al. 2005, K. Kawakami in litt. 2007, Oh et al. 2010).

Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s): The main threat is deforestation for timber and agriculture 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 and suffers from human disturbance (Anon. 2009). 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.

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
It is legally protected in Japan and Hong Kong. Birds may occur in protected areas in Japan and it has been recorded in Quezon National Park, Philippines. Environmental Impact Assessments are conducted prior to major developments in Japan, and if this species is identified using a site mitigation measures are taken (K. Kawakami in litt. 2007).

Conservation Actions Proposed
Survey its breeding range in Japan and its wintering range in the Philippines. Establish a monitoring programme of its breeding and wintering populations. Study its home-range requirements using radio-telemetry. Protect and manage forests in its breeding and wintering grounds. Ensure official protection throughout its range and strengthen and enforce legislation to prevent the sale of this (and other threatened) species. Establish public-awareness programmes concerned with its conservation. Control and monitor invasive species where appropriate within its range.


Citation: BirdLife International 2012. Gorsachius goisagi. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 26 November 2014.
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