Abstract
The gray-necked wood-rail (Aramides cajanea) is a fairly large (length 14-15 inches), secretive, but conunon species of rail native to much of tropical America. Eight sub-species are distributed from northern Argentina to southern Mexico. This species normally frequents swamps, marshes and humid forest areas up to 1900 meters in elevation (Todd and Carriker, 1922), where it feeds primarily on arthropods and small vertebrates, as well as some seeds and fruits. Locally, it is known as "cocaleca gris", derived from imitations of its calls.
The gray-necked wood-rail is a particularly striking bird, with coloration of the body primarily olive, with a rustcolored breast, and gray neck and head. Its legs are a brilliant pink, its beak yellowish-green, and iris reddish-orange. Sexes are similar in appearance, although the female may tend to be slightly larger.
Generally, the gray-necked wood-rail is a hardy species in captivity, but one which requires plenty of space, vegetation for cover, and water. Ripley (1977) notes one report of this species in a captive situation. The aviculturist referred to found the pair to be quite opposite in behavior-the female tended to be quite shy and secretive, while the male was unafraid of humans. Rutgers and Norris (1970) state that the gray-necked wood-rail was first bred in captivity in 1868 at the Jardin d'Acclimatation in Paris, but records show that they have not been kept or bred regularly by either zoological institutions or private aviculturists until recently. The July 1983 ISIS {International Species Inventory System) lists seven participating institutions presently holding this species. Two of these institutions (including the National Aquarium in Baltimore) have successfully reproduced the gray-necked wood-rail since July of 1978.
MANAGEMENT
One adult, wild-caught pair of graynecked wood-rail has been housed at the National Aquarium in Baltimore in a 65,000 cubic foot tropical rain forest since July 1981, when the exhibit opened to the public. The glass-covered exhibit is pyramidal in shape, having an 80 foot by 80 foot by 115 foot ground plan, and is 70 feet high at the peak. The exhibit has been planted to show a naturalistic stratification of Neotropical ecological zones (emergent, canopy, lower tree, shrub, ground, field, and marsh). Fifteen-foot high concrete "gunnite" walls covered with vines and epiphytes surround the large central planted area, providing cliffs and outcroppings for additional habitat availability. Several pools approximately 6 feet in diameter and 3 feet deep, a 40 foot running stream and 2 waterfalls are also present. All water sources in the exhibit are maintained on a closed, filtered system.
Inhabitants of this exhibit include over 35 species of Neotropical waders, waterfowl, psittacines, softbills, and seedeaters, 4 species of iguanid lizards, and a two-toed sloth. Nearly all species are free-ranging throughout the exhibit. Only one pair of gray-necked wood-rail is housed in the tropical rain forest exhibit, as literature states that breeding adults are extremely territorial in a captive situation and throughout the year will attack and maim others of their own kind without hesitation. Somewhat related species though, such as the purple gallinule (Porphyrula martinica) and the gray-winged trumpeter (Psophia crepitans) are successfully kept in the exhibit without ill effects.
Climate in the exhibit varies slightly with the seasons, but attempts are made to maintain a 7 5-80 ° F temperature and 60-70% relative humidity year round. Photoperiod is difficult to control, due to late night openings on weekends throughout the year. Twelve to fourteen hours of light are received on these weekend days, while a normal midAtlantic photoperiod is maintained on the remaining days.
The adult pair of gray-necked woodrail tends to inhabit the heavier growth locations of the exhibit. High elevation and thickly planted beds of Lantana sp. plants are the primary habitat locations during mid-day hours, while lower elevation shadowed areas bordering the stream are favored during early morning and late afternoon hours. Preferred roosting areas at night are the upper exposed branches of emergent trees in the exhibit. Highest activity levels appear to occur in early morning and late afternoon when duetting vocalizations, "Keeko, Keeko, Keeko, Ko, Ko, Ko, Ko, Ko" are regularly heard. Frequency of vocalizations tends to increase during active reproductive periods.
The primary diet for the adult graynecked wood-rail consists of soaked cat and dog chow, crickets, meal worms, waxworms, chopped smelt and krill, mixed into a standardized "insectile mix" base. The food is offered on the ground in metal trays twice daily in several designated food station locations throughout the exhibit.