Boat-billed heron explained

The boat-billed heron (Cochlearius cochlearius), colloquially known as the boatbill, is an atypical member of the heron family. It is the only member of the genus Cochlearius and was formerly placed in a monotypic family, the Cochleariidae. It lives in mangrove swamps from Mexico south to Peru and Brazil. It is a nocturnal bird, and breeds semicolonially in mangrove trees, laying two to four bluish-white eggs in a twig nest.

Taxonomy

In 1760 the French zoologist Mathurin Jacques Brisson included a description of the boat-billed heron in his Ornithologie based on a specimen collected in French Guiana. He used the French name La Cuillière and the Latin Cochlearius.[1] Brisson placed the species in a new genus Cochlearius (with the same name as that of the species).[2] When in 1766 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the twelfth edition, 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 Cancroma cochlearia, and cited Brisson's work.[3]

Although Brisson coined Latin names, these do not conform to the binomial system and are not recognised by the International Commission on Zoological Nomenclature (ICZN).[4] However, Brisson also introduced names for genera and these are accepted by the ICZN.[5] [6] [7] The boat-billed heron is now placed in Brisson's genus and has the tautonym Cochlearius cochlearius.[8] The name Cochlearius is from the Latin, , or for a "spoon in the form of a snail shell".[9]

There are five subspecies:[8]

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.[10] 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.[11]

Distribution and habitat

Boat-billed herons range from Mexico to Peru, Brazil, and northeastern Argentina.[12] They are nonmigratory birds that tend to live in seasonal lagoons and estuaries, and nest in mangroves.[13] [14]

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.[15] 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 and Macrobrachium,[16] and small fish such as Dormitator latifrons, a species of sleeper goby.[17] Other fish preyed upon include mullet, snook, and catfish.[16] 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.

Further reading

External links

Notes and References

  1. Book: Brisson, Mathurin Jacques . Mathurin Jacques Brisson . 1760 . Ornithologie, ou, Méthode contenant la division des oiseaux en ordres, sections, genres, especes & leurs variétés . 5 . fr, la . Paris . Jean-Baptiste Bauche . 506–508 . The two stars (**) at the start of the section indicates that Brisson based his description on the examination of a specimen.
  2. Book: Brisson, Mathurin Jacques . Mathurin Jacques Brisson . 1760 . Ornithologie, ou, Méthode Contenant la Division des Oiseaux en Ordres, Sections, Genres, Especes & leurs Variétés . fr, la . Vol. 1, p. 48, Vol. 5, p. 506 . Paris . Jean-Baptiste Bauche .
  3. Book: Linnaeus, Carl . Carl Linnaeus . 1766 . Systema naturae : per regna tria natura, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis . 12th . 1, Part 1 . Laurentii Salvii . Holmiae (Stockholm) . la . 233 .
  4. Allen . J.A. . Joel Asaph Allen . 1910 . Collation of Brisson's genera of birds with those of Linnaeus . Bulletin of the American Museum of Natural History . 28 . 317–335 . 2246/678.
  5. Book: Hemming . Francis . 1958 . 1911 . Opinions and Declarations Rendered by the International Commission on Zoological Nomenclature . 1 Section B . London . International Trust for Zoological Nomenclature . Opinion 37: Shall the genera of Brisson's "Ornithologia," 1760, be accepted . 87–88 . http://biodiversitylibrary.org/page/34612774 .
  6. Hemming . Francis . 1962 . Brisson, 1760 "Ornithologie" Proposed restriction on validation granted under the plenary powers to certain portions of that work Z.N.(S.) 702 . Bulletin of Zoological Nomenclature . 19 . 1 . 9–14 .
  7. China . W.E. . 1963 . Direction 105: Brisson, 1760, Ornithologie: restriction to certain portions of that work of the validation granted under the Plenary Powers . Bulletin of Zoological Nomenclature . 20 . 5 . 343–344 .
  8. Web site: Gill . Frank . Frank Gill (ornithologist) . Donsker . David . 2019 . Storks, ibis, herons . World Bird List Version 9.1 . International Ornithologists' Union . 9 April 2019 .
  9. Web site: Jobling . J.A. . 2019 . Key to Scientific Names in Ornithology . del Hoyo . J. . Elliott . A. . Sargatal . J. . Christie . D.A. . de Juana . E. . Handbook of the Birds of the World Alive . Lynx Edicions . 10 April 2019 .
  10. Rand. A. L.. A Display of the Boat-Billed Heron, Cochlearius cochlearius. The Auk. April 1966. 83. 2. 304–306. 10.2307/4083025. 4083025. free.
  11. Haverschmidt. F.. Notes on the Boat-Billed Heron in Surinam. The Auk. January 1969. 86. 1. 130–131. 10.2307/4083548. 4083548. free.
  12. Gomez. Jaime. Gil-Delgado. Jose A.. Monros. Juan S.. Double-Brooding in the Boat-Billed Heron. Waterbirds: The International Journal of Waterbird Biology. August 2001. 24. 2. 282. 10.2307/1522043. 1522043.
  13. Kushlan. James A.. Feeding Repertoire of the Boat-Billed Heron (Cochlearius cochlearius). Waterbirds. September 2009. 32. 3. 408–414. 10.1675/063.032.0305. 84296805 .
  14. Mock. Douglas W.. Feeding Methods of the Boat-Billed Heron, a Deductive Hypothesis. Auk. 1975. 92. 3. 590–592. 10.2307/4084617 . 4084617 .
  15. Gómez. J. Gil-Delgado. JA. Monrós. JS. Breeding success of a colony of Boat-billed Herons Cochlearius cochlearius (Ciconiiformes: Ardeidae) in pasturelands of Costa Rica. Revista de Biología Tropical. December 2006. 54. 4. 1131–4. 10.15517/rbt.v54i4.14087. 2024-06-03. 18457150. free.
  16. Web site: Cochlearius cochlearius (Boat-billed Heron) . 2023-08-01 . sta.uwi.edu.
  17. Biderman. John O.. Dickerman. Robert W.. Feeding Behavior and Food Habits of the Boat-billed Heron (Cochlearius cochlearius). Biotropica. March 1978. 10. 1. 33. 10.2307/2388102. 2388102. 1978Biotr..10...33B .

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