Least Bittern | |
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Conservation status | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Pelecaniformes |
Family: | Ardeidae |
Genus: | Ixobrychus |
Species: | I. exilis |
Binomial name | |
Ixobrychus exilis (Gmelin, 1789) |
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Subspecies | |
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Distribution map of Least Bittern Yellow: breeding, green: year-round, blue: nonbreeding |
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Synonyms | |
Ardetta exilis, Ardetta neoxena, Ixobrychus exilis neoxenus, Ixobrychus neoxenus |
The Least Bittern (Ixobrychus exilis) is a small wading bird, the smallest heron found in the Americas.
This bird's underparts and throat are white with light brown streaks. Their face and the sides of the neck are light brown; they have yellow eyes and a yellow bill. The adult male is glossy greenish black on the back and crown; the adult female is glossy brown on these parts. They show light brown parts on the wings in flight.
These birds nest in large marshes with dense vegetation from southern Canada to northern Argentina. The nest is a well-concealed platform built from cattails and other marsh vegetation. The female lays 4 or 5 eggs. Both parents feed the young by regurgitating food. A second brood is often produced in a season.
These birds migrate from the northern parts of their range in winter for the southernmost coasts of the United States and areas further south, travelling at night.
They mainly eat fish and insects, which they capture with quick jabs of their bill while climbing through marsh plants.
The numbers of these birds have declined in some areas due to loss of habitat. They are still fairly common, but more often heard than seen. They prefer to escape on foot and hide than to take flight. These birds make cooing and clucking sounds, usually in early morning or near dusk.
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Least Bittern was originally described in 1789 by J. F. Gmelin based on specimens from Jamaica.[2]
Least Bittern forms a superspecies with Little Bittern and Yellow Bittern.[2]
There are five widely recognised subspecies.[2][3]
Birds from Ecuador are sometimes assigned to a sixth subspecies, limoncochae:[2] North American birds were formerly divided into two subspecies, eastern exilis and western hesperis, but this is no longer believed to be a valid distinction.[3][4]
A dark rufous morph, "neoxenus", termed "Cory's Bittern" or "Cory's Least Bittern" was originally described by Cory as a separate species in 1885, from a specimen collected on or near the Caloosahatchee River, near Lake Okeechobee, in southwest Florida; Cory stated that the specimen was "without doubt perfectly distinct from any other known species".[5][6] Further specimens followed over the next decades, from Florida,[7][8][9][10] Michigan,[11][12] Illinois,[13][14] Wisconsin,[15] Ohio[16] and Ontario.[17][18][19][20][21]
Initially, Cory's Least Bittern was accepted as a valid species, with Elliott Coues and Richard Bowdler Sharpe both including it in published species lists.[14] However, as early as 1892, doubts were raised about the validity of Cory's Least Bittern as a separate species.[8] Nonetheless, in 1896, Frank Chapman wrote a detailed paper supporting its retention as a valid species.[22] Outram Bangs later argued, in 1915, that this view was wrong, and proposed that Cory's should become a junior synonym of Least Bittern.[23] This view eventually prevailed, with the American Ornithologists' Union removing the species from their list of North American birds in 1923,[24] although others held dissenting views until at least 1928.[25]
Cory's Least Bittern was once fairly common, but it is now exceptionally rare, with only five sightings since 1950.[26] More than 50 per cent of the historical records are from the Toronto region of Ontario.[3] Initially known only from the North American subspecies exilis, it was first recorded in the South America subspecies erthyromelas in 1967.[27]
The Least Bittern is protected under the Migratory Bird Treaty Act of 1918.[1]