TAPACULOS: RhinocryptidaeRUSTY-BELTED TAPACULO (Liosceles thoracicus): SPECIES ACCOUNT
Tapaculos are a diverse family of small perching birds that live in Central and South America. They range in size from about 4 to 9 inches (10 to 23 centimeters) and weigh anywhere from 0.4 to 6.5 ounces (11 to 185 grams). Tapaculos are one of the most primitive families of songbirds.
Tapaculos are also one of the most varied families of birds. The fifty or so species have only a few physical characteristics in common. Tapaculos are very poor flyers. They have short, rounded wings, but unusually strong feet and large claws. Internally the sternum, or breastbone, of these birds is different from the sternum of birds that are better flyers. In most birds, even domestic chickens, the sternum has a projection or bulge called a keel. The keel creates more surface area for the muscles used in flight to attach to the bone. Birds like tapaculos that are nearly flightless do not need this extra area where flight muscles can attach, so their breastbones do not have a keel.
Tapaculos are generally solid color grayish or brown birds, although some have lighter-colored spots or patterns. In most species, the males and females look similar, although the females tend to be slightly smaller. Most tapaculos have short tails. Their feathers fall out easily and it is thought that this is a way of fooling predators, animals that are hunting them.
Different species of tapaculo may be difficult or impossible to tell apart by sight. Some species look alike and can only be identified based on their song, their weight, and the habitat in which they live. Others are so similar that they can only be told apart by genetic testing. Ornithologists, scientists who study birds, are not in complete agreement about how many species of tapaculos exist and how they should be classified.
Tapaculos are found from Costa Rica in southern Central America to Tierra del Fuego, Argentina, at the southern tip of South America. Many species live in the Andes Mountains in western South America. They are mostly absent from the hot, humid rainforest of the Amazon and Orinoco river basins in Brazil and Venezuela.
Most species of tapaculos prefer high, cool, tropical mountain rainforests. Only one kind of tapaculo lives in the lowland Amazon rainforest. Several members of this family have adapted to life in dry, desert climates or dry grasslands. Some species have extremely limited habitats, which puts them at risk for extinction, or dying out. For example, one type of tapaculo lives only in the tall grass of certain marshes in Brazil. Species tend to separate by elevation, height of land above sea level, so that in the Andes, a single mountain may be home to four or five species of tapaculos all living at different elevations that do not overlap.
Tapaculos eat mainly insects and spiders. Some species also eat berries. These birds feed by walking or hopping across the forest floor, then scraping their feet against the ground, turning over the moss and leaves with their strong claws to look for bugs. A few species hop through low branches eating the insects they find there.
WHO IS IN AND WHO IS OUT?
Tapaculos are some of the hardest birds to classify. Scientists are still not sure exactly how many species there are in this family. New species are being discovered, and in 1997 several species were reclassified. In the past, tapaculos were considered separate species if they had different songs or lived in different environments and did not interbreed. Today genetic and biochemical evidence suggests that some of these classifications may be wrong and the number of tapaculo species may change again.
BEHAVIOR AND REPRODUCTION
Tapaculos have not been well studied, and not much is known about their behavior. They tend to be shy birds that spend much of their time on the forest floor. They are so hard to observe, in fact, that scientists know several species only by their song. It appears that these birds identify each other and choose their mates by sound rather than sight. This may be one reason why their feathers are dull and why some species look the same, but sound different.
In the tapaculos that have been studied, it appears that birds who mate form permanent pairs, but if one member of the pair dies, another mate is chosen almost immediately. The nests of fewer than half the species of all tapaculos have been observed. Of those that are known, most species build their nests in the ground at the end of tunnels. The birds either dig the tunnels themselves or take over empty animal burrows. Some species use hollow logs instead of digging tunnels. A few build cup nests in low branches.
Normally tapaculos lay two or three eggs. In some species both males and females sit on, incubate, the eggs for about two weeks before they hatch. The young birds are naked when they hatch and are cared for by both parents until they are ready to leave the nest several weeks later.
TAPACULOS AND PEOPLE
Because they are such shy birds, tapaculos are often overlooked by people who are not trained birdwatchers. They are mainly studied by ornithologists interested in the evolution of different families of birds.
Two species of tapaculos are Critically Endangered, facing an extremely high risk of extinction in the wild, and may be extinct. Streseman's bristlefront and the Bahai tapaculo both live in eastern Brazil and are in danger of dying out because of loss of habit from deforestation of their naturally small range.
One other tapaculo, the tall-grass wetland tapaculo, that lives in the marshes of southern Brazil, is Endangered, facing a high risk of extinction, due to human development. The population of Tacarcula tapaculos is holding steady, but is considered Vulnerable, facing a high risk of extinction, because of clearing of forests and potential road building in its habitat along on the border of Panama and Colombia. Five other species are considered Near Threatened, in danger of becoming threatened with extinction, and face declining populations.
Physical characteristics: The rusty-belted tapaculo is one of the larger tapaculos. They are about 7.5 inches (19 centimeters) long and weigh about 1.5 ounces (42 grams). Rusty-belted tapaculos live on the forest floor. Their dark gray-brown back helps them blend in well with their environment. Their throat and breast are white, with a rusty reddish breast band that gives them their name. They have a black, white, and rusty pattern on their undersides.
Geographic range: Rusty-belted tapaculos live in South America in southeastern Colombia, western Brazil, and neighboring parts of Peru and Ecuador.
Habitat: Unlike many tapaculos that prefer higher, cooler elevations, rusty-belted tapaculos live in humid lowland rainforests on the forest floor.
Diet: Like all tapaculos, these birds eat insects. They feed by walking or hopping slowly along the forest floor looking for prey.
Behavior and reproduction: Rusty-belted tapaculos build underground nests among the roots of trees. Little is known about their reproductive behavior, because they are shy and difficult to observe.
Rusty-belted tapaculos and people: These birds have little interaction with people and are rarely seen. They are of interest mainly to ornithologists and birdwatchers.
Conservation status: Rusty-belted tapaculos are not threatened or in danger of extinction. ∎
FOR MORE INFORMATION
Ridgley, Robert S., and Guy Tudor. The Birds of South America. Vol 2, The Suboscine Passerines. Austin, TX: University of Texas Press, 1994.