Cochlearius Cochlearius
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The boat-billed heron (''Cochlearius cochlearius''), colloquially known as the boatbill, is an atypical member of the
heron Herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 75 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genus ''Botaurus'' are referred to as bi ...
family. It is the only member of the genus ''Cochlearius'' and was formerly placed in a
monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
family, the Cochleariidae. It lives in
mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...
swamps from
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
south to
Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...
and
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
. It is a nocturnal bird, and breeds semi colonially in
mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...
trees, laying two to four bluish-white eggs in a twig nest.


Taxonomy

In 1760 the French zoologist
Mathurin Jacques Brisson Mathurin Jacques Brisson (; 30 April 1723 – 23 June 1806) was a French zoologist and natural philosophy, natural philosopher. Brisson was born on 30 April 1723 at Fontenay-le-Comte in the Vendée department of western France. Note that page 14 ...
included a description of the boat-billed heron in his ''Ornithologie'' based on a specimen collected in
French Guiana French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...
. He used the French name ''La Cuillière'' and the Latin ''Cochlearius''. The two stars (**) at the start of the section indicates that Brisson based his description on the examination of a specimen. Brisson placed the species in a new genus ''Cochlearius'' (with the same name as that of the species). When in 1766 the Swedish naturalist
Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
updated his ''
Systema Naturae ' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...
'' for the
twelfth edition Twelfth can mean: *The Twelfth Amendment to the United States Constitution *The Twelfth, a Protestant celebration originating in Ireland In mathematics: * 12th, an ordinal number; as in the item in an order twelve places from the beginning, follo ...
, he added 240 species that had been previously described by Brisson. One of these was the boat-billed heron. Linnaeus included a brief description, coined the
binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...
''Cancroma cochlearia'', and cited Brisson's work. Although Brisson coined Latin names, these do not conform to the
binomial system The binomial system () is a voting system that was used in the legislative elections of Chile between 1989 and 2013. The binomial system is the D'Hondt method with an open list where ''every'' constituency returns ''two'' (hence the name) rep ...
and are not recognised by the
International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...
(ICZN). However, Brisson also introduced names for genera and these are accepted by the ICZN. The boat-billed heron is now placed in Brisson's genus and has the
tautonym A tautonym is a scientific name of a species in which both parts of the name have the same spelling, such as '' Rattus rattus''. The first part of the name is the name of the genus and the second part is referred to as the ''specific epithet'' i ...
''Cochlearius cochlearius''. The name ''Cochlearius'' is from the Latin , '','' or ' for a "spoon in the form of a snail shell". There are five
subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
: * ''C. c. zeledoni'' ( Ridgway, 1885) – west Mexico * ''C. c. phillipsi'' Dickerman, 1973 – east Mexico, Belize * ''C. c. ridgwayi'' Dickerman, 1973 – south Mexico to Honduras * ''C. c. panamensis'' Griscom, 1926 – Costa Rica and Panama * ''C. c. cochlearius'' (
Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
, 1766) – north and central South America


Description

The boat-billed heron grows to about long. Adults are pale grey to white in color, with chestnut-colored abdomens and black flanks. The massive, broad, scoop-like bill, which gives rise to this species' name, is mainly black. This bird is also adorned with a crest which is thought to be used in mate attraction as it is larger in males. The sexes are similar in appearance, the main differences being that females are slightly smaller, grayer in appearance, and have shorter crests than males. Newly hatched nestlings have green-yellow skin, with their upperparts covered in gray down feathers. Their upper bill is black and they have green-yellow legs. Juveniles are darker in color than adults and lack a crest.


Distribution and habitat

Boat-billed herons range from Mexico to Peru, Brazil, and northeastern Argentina. They are nonmigratory birds that tend to live in seasonal
lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...
s and
estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...
, and nest in mangroves.


Behaviour and ecology


Breeding

Boat-billed herons breed during the rainy season and have been recorded as producing two clutches during this time, laying their first clutch in February during the end of the dry season. Their clutch sizes range from two to four eggs, with more eggs being laid during the first nesting period than the second. They usually nest in colonies but have been observed nesting solitarily. Human disturbance can lead to a decrease in reproductive success, as herons tend to avoid human contact and will abandon nests if necessary.


Food and feeding

Boat-billed herons feed on small mammals, amphibians, annelids, molluscs, insects, crabs, shrimp such as ''
Penaeus ''Penaeus'' is a genus of prawns, including the giant tiger prawn (''P. monodon''), the most important species of farmed crustacean worldwide. Taxonomy The genus has been reorganised following a proposition of Pérez Farfante and Kensley bas ...
'' and ''
Macrobrachium ''Macrobrachium'' is a genus of freshwater prawns or shrimps characterised by the extreme enlargement of the second pair of pereiopods, at least in the male. Species It contains these species: *'' Macrobrachium acanthochirus'' F. Villalobos, ...
'', and small fish such as ''
Dormitator latifrons ''Dormitator latifrons'', the Pacific fat sleeper, is a species of fish in the family Eleotridae found on the Pacific Ocean, Pacific coast of the Americas from around Palos Verdes, California, to Peru, where it can be found in stagnant or slug ...
'', a species of sleeper goby. Other fish preyed upon include mullet, snook, and
catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...
. They tend to forage in vegetative streams, shallow water, and lagoons. When foraging in streams, they use low-hanging branches and mangrove roots to stand over the water. In ponds, they will walk slowly through the water up to deep or will forage near the water's edge. In order to capture prey they will lunge at fish or scoop the surface of the water with their bills which are uniquely shaped for this method of capture. Additionally, they have been observed using two different feeding techniques; standing and slowly stalking prey, or disturbing the water and chasing prey. Boat-billed herons will forage nocturnally and have been seen leaving the roost 30 minutes after sundown to feed. It has been observed that they do not feed when a light source is present such as daylight, moonlight, or artificial light. One study hypothesized that in order to forage for food in the dark and in shallow, muddy water, their bills are sensitive to touch, which helps them feel for their prey.


References


Further reading

* * * ''A Guide to the Birds of Costa Rica'' by Stiles and Skutch


External links

*
Photos of the boat-billed heron
{{Taxonbar, from1=Q210341, from2=Q10749386 Ardeidae Birds of Trinidad and Tobago Wading birds Birds of Brazil Birds of Peru Birds of Mexico Birds of South America Birds of Central America Birds described in 1766 Taxa named by Carl Linnaeus Articles containing video clips