Striated Heron
Encyclopedia
The Striated Heron, Butorides striata, also known as Mangrove Heron, Little Heron or Green-backed Heron
Green-backed Heron
"Green-backed Heron" is a collective term for certain herons. Small and compact among herons, these birds often feature green plumage – rare among the Ardeidae –, in particular on the back, wings and scapulars....
, is a small 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"....
. Striated Herons are mostly non-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...
and noted for some interesting behavioral traits. Their breeding habitat is small wetlands in the Old World
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" ....
tropics from west Africa to Japan and Australia, and in South America. Vagrants have been recorded on oceanic islands, such as Chuuk
Chuuk
Chuuk — formerly Truk, Ruk, Hogoleu, Torres, Ugulat, and Lugulus — is an island group in the south western part of the Pacific Ocean. It comprises one of the four states of the Federated States of Micronesia , along with Kosrae, Pohnpei, and Yap. Chuuk is the most populous of the FSM's...
and Yap
Yap
Yap, also known as Wa'ab by locals, is an island in the Caroline Islands of the western Pacific Ocean. It is a state of the Federated States of Micronesia. Yap's indigenous cultures and traditions are still strong compared to other neighboring islands. The island of Yap actually consists of four...
in the Federated States of Micronesia, the Marianas and Palau; the bird recorded on Yap on February 25, 1991, was from a continental Asian rather than from a Melanesia
Melanesia
Melanesia is a subregion of Oceania extending from the western end of the Pacific Ocean to the Arafura Sea, and eastward to Fiji. The region comprises most of the islands immediately north and northeast of Australia...
n population, while the origin of the bird seen on Palau on May 3, 2005 was not clear.
This bird was long considered to be conspecific with the closely related North American species, the Green Heron
Green Heron
The Green Heron is a small heron of North and Central America. It was long considered conspecific with its sister species the Striated Heron , and together they were called "Green-backed Heron"...
, which is now usually separated as B. virescens, as well as the Lava Heron
Lava Heron
The Lava Heron, Butorides sundevalli, also known as the Galapagos Heron, is a species of heron endemic to the Galapagos Islands. The adult is slate-grey, which helps it blend in with the hardened lava. The back feathers typically have a silvery sheen and it has a short crest on its head...
of the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
(now B. sundevalli, but often included in B. striata, e.g. by BirdLife International
BirdLife International
BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...
); collectively they were called "green-backed heron
Green-backed Heron
"Green-backed Heron" is a collective term for certain herons. Small and compact among herons, these birds often feature green plumage – rare among the Ardeidae –, in particular on the back, wings and scapulars....
s".
Description and ecology
These birds stand still at the water's edge and wait to ambush prey, but are easier to see than many small heron species. They mainly eat small fish, frogs and aquatic insects. They sometimes use bait, dropping a feather or leaf carefully on the water surface and picking fish that come to investigate.
They nest in a platform of sticks measuring between 20–40 cm long and 0.5–5 mm thick. The entire nest measures some 40–50 cm wide and 8–10 cm high outside, with an inner depression 20 cm wide and 4–5 cm deep. It is usually built in not too high off the ground in shrubs or trees but sometimes in sheltered locations on the ground, and often near water. The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
is 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, which are pale blue and measure around 36 by 28 mm.
An adult bird was once observed in a peculiar and mysterious behavior: while on the nest, it would grab a stick in its bill and make a rapid back-and-forth motion with the head, like a sewing machine's needle. The significance of this behavior is completely unknown: While such movements occur in many other nesting birds where they seem to compact the nest, move the eggs, or dislodge parasites, neither seems to have been the case in this particular Striated Heron.
Young birds will give a display when they feel threatened, by stretching out their necks and pointing the bill skywards. In how far this would deter predators is not known.
Widespread and generally common, the Striated Heron is classified as a Species of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
by the IUCN; this holds true whether the Lava Heron
Lava Heron
The Lava Heron, Butorides sundevalli, also known as the Galapagos Heron, is a species of heron endemic to the Galapagos Islands. The adult is slate-grey, which helps it blend in with the hardened lava. The back feathers typically have a silvery sheen and it has a short crest on its head...
is included in B. striata or not.