Oilbird plumage (feathers) is the color of cinnamon, and the bird's reddish brown feathers are dotted with white spots. The long tail is colored by faint black bars, lines of color. Males and female birds have similar coloring, and females are slightly smaller than males.
The oilbird is the only member of the Steatornithidae family. While they resemble owls, order Strigiformes, oilbirds belong to the Caprimulgiformes order. Like other families in the Caprimulgiformes order, the oilbird has a large gape, the width of the mouth when it's open.
Birds in the Caprimulgiformes and Strigiformes orders are nocturnal, active at night, and their large eyes provide the strong vision needed to see at night. Both owls and oilbirds have hooked bills, but the owl has sharp claws on its feet. The owl uses these talons (TAL-unz) to capture prey, animals hunted as food. Oilbirds have small feet and eat only fruit.
Oilbirds eat fruit that is rich in fat and oil, which provides the energy needed to fly. When chicks are fed these fruits before they are able to fly, they become very fat, often growing larger than the adults. While adult birds weigh from 13 to 16 ounces (375 to 455 grams), a seventy-day-old oilbird chick weighs approximately 21 ounces (600 grams). As the young bird develops, the parents feed it less often. The combination of less food and growing into adulthood causes the oilbird to lose weight. Oilbirds got their name from the fact that in the past chicks were captured and boiled down in order to make oil.
Adult oilbirds measure 17 to 19 inches (43 to 49 centimeters) in length. The bird has blue eyes and a yellow beak with whisker-like bristles on both sides. The oilbird uses its bill to pluck fruit from trees.
Since oilbirds have short feet, they do not perch or stand on trees. Instead, the bird rests, which is like sitting. At rest, the head of the oilbird is lower than its tail. Furthermore, their feet are so weak that they do very little walking, instead they fly to get from one place to another.
Their wingspan, the distance between the fully spread wings, is approximately 37.5 inches (95 centimeters). The wings are wide and slotted so that the oilbird can fly slowly while carrying loads into the dark caves where they live during the day. At night, oilbirds use their powerful wings to fly as far as 75 miles (120 kilometers) in search of food.