Birds of the World

COAST BIRDS
  Contents
  Index
WORLD BIRDS
  Contents
  Index

ANECDOTES

 
 
 
 

TRAITS
 Ratites
 Tinamous
 Cracids/Galli
 Waterfowl
   Screamers
   Ducks

 Penguins
 Loons
 Grebes
 Procellarids
   Albatrosses
   Petrels
   Storm-Petrels

Totipalmate Swm

   Tropicbirds
   Gannets/Boobies
   Pelicans
   Cormorants
   Anhingas
   Frigatebirds

 
Waders
   Herons
   Ibises
   Storks  

 NW Vultures
 Flamingos
 Raptors
 Gruiformes
   Buttonquail
   Bustards
   Cranes
   Rails

 Shorebirds
   Sandgrouse
   Plovers
   Oystercatchers
   Stilts
   Sandpipers
   Gulls/Terns
   Auks

 Pigeons
 Parrots
 Turacos
 Cuckoos
 Owls
 Frogmouths
 Nightjars
 Swifts/Humbd
 Colies
 Coraciae

   Hornbills
   Hoopoes
   Trogons
   Rollers
   Kingfishers
   Bee-eaters
   Jacamars/Puffbd

 
Pici
   Honeyguides
   Woodpeckers
   Barbets/Toucans

PASSERINES
   NZ WRENS
   OW SUBOSC

      Broadbills
      Pittas

 NW SUBOSC
   NW Flycatchers

   Becards
   Cotingas
   Manakins
   Antbirds
   Ovenbirds
   Woodcreepers
   Antthrushes
   Tapaculos 

 OSCINES
 Lyre-/Scrub-birds
 Bowerbirds
 Aust. Wrens
 Honeyeaters
 Scrubwrens
 Aust. Robins
 Kinglets
 Shrikes
 Vireos
 Whistlers
 Corvids
 Birds-of-Paradse
 OW Orioles
 Cuckoo-shrikes
 Fantails
 Drongos
 Monarchs
 Bush-shrikes
 Wattle-eyes
 Vangas
 Waxwings
 Dippers
 Thrushes
 OW Flycatchers
 Starlings
 Mimids
 Nuthatches
 N Creepers
 Wrens
 Gnatcatchers
 Tits/Parids
 Larks
 Swallows
 Leaf-Warblers
 Bulbuls
 Cisticolas
 White-eyes
 Babblers
 OW Warblers
 Flowerpeckers
 Sunbirds
 OW Sparrows
 Accentors
 Pipits
 Estridids
 Weavers
 Whydahs
 9-prim. Oscines

   Fringillines
   Carduelines
   Hawaiian Honycrp
   NW Sparrows
   NW Warblers
   Tanagers
   Cardinals
   NW Blackbirds

TOP

 
Cuculiformes / Opisthocomiformes - Hoatzin
 
Skip to:   
Musophagiformes, Cuculiformes, Opisthocomiformes
Families: Musophagidae - Plantain-eaters, Turacos, Go-away Birds
   Cuculidae - Cuckoos, Roadrunners, Anis
   Opisthocomidae -Hoatzins
 
Images:   
Knysna Turaco, Great Blue Turaco, European Cuckoo, Roadrunner, Smooth-billed Ani, Hoatzin
 
  (Order Opisthocomiformes - Hoatzins) incertae sedis
Wiki     ToL     EoL
  Placed in the Cuculiformes by Sibley and Ahlquist (1990) and the Gruiformes by Clements (2007). With the suggestion that they may more properly related to doves, giving them their own order seems merited.
 
  Family Opisthocomidae - Hoatzins
Wiki     ToL     EoL
  1 species, 1 genus (Opisthocomus hoazin). Amazon and Orinoco delta, South America. They are relatively tame and are often seen on cruises in the upper Amazon Basin. Take your camera.
   The Hoatzin is a slender, brownish bird with lighter streaks and buffy-tipped tail feathers. It is about the size of a pheasant. The head is small and has a ragged, bristly crest of reddish-brown feathers, bare facial skin, and a red eye. The bill is short, stout, and laterally compressed. It is somewhat decurved. The bill has a hinged attachment with the skull ao the upper mandible is mobile. They are schizognathous, They have broad, rounded wings and weak flight - the keel is reduced and flight muscles are small. Their sternum is deeply incised in front to provide space for their large crop. They have 10 primaries, 11 secondaries and 10 rectrices. Their wing is eutaxic. Their tail is broad and rounded. Their legs are strong and their feet have 4 toes - the foot is large with an incumbent hallux (it is not zygodactyl but they have a small accessory process found in zygodactylous birds). Hoatzins have an aftershaft on their contour feathers. Pelvic musculature is ABXY+ and they have a feathered oil gland.
   Females have a slightly larger crest than males. Upperparts are dark with white streaks. The outer 9 primaries are rufous. The chin and breast are reddish-brown and the belly and underwing coverts are rufous. The tail is dark with a buff tip.
   Hoatzins are arboreal and live in flooded forests and riparian edges of lakes, oxbows, rivers and streams of northern South America in the Guianas, Venezuela, and the basins of the Orinoco and Amazon rivers. They may also be found around brackish or salt water bays. They are somewhat crepuscular but will feed at night. To escape predators, they climb through brush - occasionally flying short distances. Hoatzins spend most of the day resting on their sternum which has a large callosity to provide support.
   They feed on leaves, flowers, and fruits of marsh plants. They prefer new growth with a high water content. Hoatzins have a large, muscular crop with a ridged interior lining. Foregut fermentation of fibrous plant material takes place in the crop and the ridged lining increases the area of uptake of the products of this fermentation. This is the only case of foregut fermentation known in birds (among mammals, ruminant ungulates, colobine monkeys, sloths, and macropodid marsupials use this process). The lower esophagus is sacculated, delaying passage of particles to the lower gut. Added fermentation occurs in the paired caeca (between intestines and the hind gut). There is a callus on the breast-region where the filled crop is rested on a branch while its contents are processed. As a result of this fermentation, they are very unpleasant to handle - the odor is overwhelming! They are called "stinkbirds."
   Their voice includes hissing and grunts.
   Hoatzins are gregarious and form large flocks when not breeding. They are generally monogamous but nest in groups of 2-7 birds, usually including an adult pair and helpers (offspring of the previous year -  cooperative breeding). Nesting groups build a flat nest of twigs in branches overhanging water. Mating may be polygamous and all members incubate eggs and care for young. 2-5 eggs hatch after about 28-30 days of incubation. Chicks hatch blind and covered sparsely with down. Their eyes open in about 24 hours. Young have two claws on their hand digits which they use to grasp branches and climb around vegetation (claws are lost before maturity but adults also use their wings for support in vegetation). Hoatzins are clumsy when moving around in vegetation and young may fall into the water (and hide there from danger - they swim well), returning to the nest when danger is past. Young have two coats of down and are fed regurgitated partially-digested leaves from the crop of adults. They fly in about 2 months and depend on their parents for food for another month.
   Note that the young of anis also use their beak, feet, and wings when climbing about near the nest and may drop to the ground and hide, returning to the nest when danger has passed.   
   The Hoatzin is sometimes considered to belong with the Gruiformes (Clements, 2007). Sibley and Monroe (1990) place them with the Cuculiformes as a sister group of the Anis. Dickinson (2003) and Harris (2009) place the family between the parrots and turacos. The Encyclopedia of Life places them in the Cuculiformes. The Tree of Life places them between turacos and doves. However, there is now some evidence that their closest living relatives are actually doves (Order Columbiformes).
     
 
Hoatzin
Hoatzin, Opisthocomus hoazin
Amazon Basin.
Photo by E. B. Pivorun
 
   
       
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   
     
  Banner. Hoatzin. Amazon Basin.