Gorsachius
Encyclopedia
Gorsachius is a genus of Old World
night heron
s typically found near water in forested regions. These are medium-sized heron
s 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.
Their behavior, especially that of the White-eared Night Heron, is relatively poorly known compared to that of other night herons, but they nest alone or in small groups, and a clutch of 2-5 egg
s has been recorded. While generally nocturnal and crepuscular
, they have been recorded feeding during the day in clouded weather. They are skulking, and known to feed on crabs, crustacean
, fish, insects, frogs and other small animals.
, but today all major authorities recognize them as separate. In addition to the species listed below, the Rufous or Nankeen Night Heron
has been placed in Gorsachius, but today all major authorities place it in Nycticorax. The four night herons in this genus are all monotypic
.
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
night heron
Night heron
The night herons are medium-sized herons in the genera Nycticorax, Nyctanassa and Gorsachius. The genus name Nycticorax derives from the Greek for “night raven” and refers to the largely nocturnal feeding habits of this group of birds, and the croaking crow-like call of the best known species, the...
s typically found near water in forested regions. These are medium-sized heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....
s which are migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
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
East Asia
East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...
, South
South Asia
South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...
and South-east Asia, while the last species, the White-backed Night Heron, is found in sub-Saharan Africa
Sub-Saharan Africa
Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...
. 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.
Their behavior, especially that of the White-eared Night Heron, is relatively poorly known compared to that of other night herons, but they nest alone or in small groups, and a clutch of 2-5 egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s has been recorded. While generally nocturnal and crepuscular
Crepuscular
Crepuscular animals are those that are active primarily during twilight, that is during dawn and dusk. The word is derived from the Latin word crepusculum, meaning "twilight." Crepuscular is, thus, in contrast with diurnal and nocturnal behavior. Crepuscular animals may also be active on a bright...
, they have been recorded feeding during the day in clouded weather. They are skulking, and known to feed on crabs, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
, fish, insects, frogs and other small animals.
Taxonomy
These night herons were formerly placed in the genus NycticoraxNycticorax
Nycticorax is a genus of night herons. The name Nycticorax derives from the Greek for “night raven” and refers to the largely nocturnal feeding habits of this group of birds, and the croaking crow-like call of the best known species, the Black-crowned Night Heron.These are medium-sized herons which...
, but today all major authorities recognize them as separate. In addition to the species listed below, the Rufous or Nankeen Night Heron
Nankeen Night Heron
The Nankeen Night Heron, Nycticorax caledonicus, also commonly referred to as the Rufous Night Heron, and in Melanesia as Melabaob, is a medium-sized heron. It is found throughout much of Australia except the arid inland, Indonesia, the Philippines, Papua New Guinea and Melanesia...
has been placed in Gorsachius, but today all major authorities place it in Nycticorax. The four night herons in this genus are all monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
.
- White-backed Night Heron, Gorsachius leuconotus
- White-eared Night Heron, Gorsachius magnificus
- Japanese Night HeronJapanese Night HeronThe Japanese Night Heron, Gorsachius goisagi, is a species of night heron found in East Asia. It breeds in Japan, and winters in the Philippines and Indonesia. It is also seen in the spring and summer in Korea and the Russian Far East....
, Gorsachius goisagi - Malayan Night HeronMalayan Night HeronThe Malayan Night Heron also known as Malaysian Night Heron, is a medium-sized heron. It is distributed in south, east and southeast Asia, breeding in India, Taiwan, China and the Philippines....
, Gorsachius melanolophus