BIOLOGY

Curassows are a long-lived (20+ year), arboreal gallinaceous group of birds found in the Central and South American tropics and subtropics.² They are in the family Cracidae, a primitive bird group in the order Galliformes, and are distantly related and similar to grouse, quail, chicken, and other fowl species. The family Cracidae contains curassows (four genera, 14 species; Box 23-1), chachalacas, and guans.³ Curassows are important in seed dispersal, as environmental indicators, and for ecotourism. Several species of curassow are highly endangered or threatened in their environment as a result of habitat destruction and hunting.⁵

Natural enemies of curassows include predatory birds, mammals, and humans. Curassows are generally monogamous, usually occurring in pairs, although trios (cock and two hens) or family groups may be found existing peacefully together. The female lays and broods two eggs (occasionally only one or up to three), with incubation lasting approximately 28 to 30 days. Females may produce four clutches per year if the eggs are removed for artificial incubation or domestic chicken brooding after the clutch is laid. Chicks are precocial, grasping and perching as soon as they are hatched; thus smaller perching should be provided for the chick within 24 hours after hatching. The chicks are fed by both parents by offering foods in their beak; curassow parents do not regurgitate for their young.

Curassows exhibit four interesting mannerisms for uncertain reasons, but believed to be for anxiety, nervousness, or courtship: (1) a rapid head flick from side to side, (2) the tail bob, (3) passing of the head over the back, such as a duck would do when preening, and (4) the wing flap. If one is not familiar with these behaviors, they could be misconstrued as neurologic conditions. It is thought that the head flick might have evolved as a defense to parasitic eye flies.¹

HOUSING

Curassows may be housed in a variety of ways depending on space limitations and general attitude of the bird. Curassow pens should be fairly large and well planted and should contain several perches of varying sizes for roosting because of the birds’ body size and their arboreal nature. It is thought that curassows spend approximately half their time perching above the ground. An enclosed section for protection from the cold and frostbite should be included in all outdoor exhibits. Curassows are not cold tolerant and are susceptible to developing frostbite when the environmental temperatures fall below approximately 40° F (4.4° C) for several consecutive days.

Males may be territorial, and two or more housed together will tend to fight. The birds may be excessively aggressive during the breeding season and may even attack zoo visitors, as well as being aggressive toward smaller birds, sometimes killing them. Depending on their personality, some curassows are not a good species for free-flight pens, whereas other individuals do very well in open spaces and will cohabitate with other species.

UNIQUE ANATOMY

Curassows are fowl-like with strong legs and feet, ample tail and wings, and a well-developed hind toe used to grasp branches. Curassows are the only group of the Cracidae family that has a developed crop. They are primarily herbivorous, with a muscular gizzard that can grind hard seeds and nuts, as well as fruit, greens, insects, and invertebrates. Because of the muscularity of the ventriculus, curassows tend to swallow small pebbles or gravel as grit.

Male birds are usually larger than the females, and both genders are vocal with a well-developed syrinx. Certain species of male curassows, Pauxi pauxi and Crax alector, have an elongated trachea, used in vocalization for increased loudness or low-pitched sounds. In the northern-helmeted curassow (Pauxi pauxi) the trachea extends under the skin, overlays the abdomen, then curves back around and up and enters the thoracic inlet.³

Some curassow species have a feathered crest on the top of the head (Crax spp.) and a wattle or specialized knob or protuberance on the caudal cere. Males have an intromittent organ, which might be used to sex young birds. Gender determination of chicks of the Crax spp. may also be done by comparing cere color, which is pink or fleshy colored in males and dusky colored in females.