Family Dendrocolaptidae
woodcreepers

Woodcreepers are in the order Passeriformes, suborder Furnarii and family Dendrocolaptidae. There are 13 genera and 50 species within the family. Woodcreepers are small to medium sized birds. Most have brown plumage with some white spots or streaks. Their tails usually have rigid shafts and spiny tips that help the birds climb trees. They are Neotropical birds found from Mexico to central Argentina. Woodcreepers live primarily in lowland tropical forests and are mainly insectivores. Some species follow swarms of army ants and eat the insects that are flushed by the ants. Most species are monogamous although some form dispersed leks. Woodcreepers are poor dispersers and, like many bird species, they are suffering from habitat loss and fragmentation. Some species are better able to cope with human disturbance than others, but preservation of their habitat is crucial. (Campbell and Lack, 1985; Dickinson, 2003; Marantz and Hutson, 2003; Marantz et al., 2003; Wetmore, 1972)

Woodcreepers are Neotropical birds; their range extends from Mexico south to central Argentina. The highest diversity of woodcreepers occurs in the lowlands of the Amazon Basin. (Campbell and Lack, 1985; Marantz and Hutson, 2003; Marantz et al., 2003; Wetmore, 1972)

Most woodcreepers live in lowland tropical rainforest. However, some species can be found in forest edge habitats, semi-open habitats, cloudforest, savanna or arid scrub. Most species are found below 1000 m, but some can be found in the mountains up to 3600 m. Species that have been able to adapt to human disturbance can be found in some suburban and urban areas. (Marantz and Hutson, 2003; Marantz et al., 2003)

Woodcreepers (occasionally known as “woodhewers”) are in the order Passeriformes, suborder Furnarii and family Dendrocolaptidae. There are 13 genera and 50 species within the family. Their closest relatives are the ovenbirds (family Furnariidae). In fact, in the past, woodcreepers were classified as a subfamily Dendrocolaptinae within the family Furnariidae.

Characteristics that distinguish woodcreepers include: holorhinal nares, horns on the Processi vocales, feather tracts with a unique arrangement (pterylosis), hind limb tendons highly ossified, outer and middle toes longer than the inner toe and joined at their base. (Dickinson, 2003; Marantz and Hutson, 2003; Marantz et al., 2003; Payne, 2003; Sibley and Ahlquist, 1990)

Woodcreepers are small to medium sized birds (13 to 36 cm and 11 to 160 g). They are typically brown, olive or rufous colored with white spots, streaks or bars. Species that live in open areas are lighter colored underneath. Their broad, rounded wings and specialized tail are often rufous colored and the tips of their remiges (flight feathers) are usually darker. Woodcreepers molt once each year, however, molting does not change their appearance. Most species are not sexually dimorphic. However, in some species the males are larger and some males are able to raise their crown feathers while females are not. Different species of woodcreepers are often very difficult to tell apart. Many species have similar behaviors, colors and shapes. Often they can only be told apart by their calls. Juveniles generally have more barring than adults, a shorter tail and a darker, shorter bill.

Bill size and shape is variable in woodcreepers and reflects foraging strategy. Bills range from long to short, thick to thin and straight to very decurved. Long-billed woodcreepers (Nasica longirostris) have a bill that is one quarter of their body length.

Woodcreepers’ tails are specialized to help them climb trees; the tail feathers have stiff, spiny shafts that are claw-like. Their foot and leg morphology also help them climb and their claws are very curved. (Campbell and Lack, 1985; Marantz and Hutson, 2003; Marantz et al., 2003; Wetmore, 1972)

Like most small birds, woodcreepers probably live on average only two to five years. (Gill, 1995)

Woodcreepers are found alone, in pairs, small family groups, or mixed species flocks. The mixed-species flocks usually include other insectivorous species that some species of woodcreepers join as they follow swarms of army ants and catch insects that the ants flush as they move through the forest.

Most species are sedentary, although some make nomadic wanderings and altitudinal shifts in response to food availability. They have an undulating flight and sing at dawn and dusk. They roost alone in cavities at night. Woodcreepers will not cross large, unforested gaps; this may become a problem for their survival as their habitat becomes increasingly fragmented.

Woodcreepers spend most of their time in trees and are morphologically adapted for tree climbing (see Physical Description). They creep or “hitch” up trees using their tail as a brace. They are very aggressive and larger species are dominant over smaller species. They defend territories, but their defensive behavior usually entails chasing intruders out of flocks rather than out of a defended area. Woodcreepers sunbathe and have been seen anting, a behavior that is thought to help prevent or remove ectoparasites. (Marantz and Hutson, 2003; Marantz et al., 2003)

The songs of woodcreepers are simple and unmusical. They often consist of a single repeated note or whistle, creating a rattle or trill. A few species have more complex calls and mates have contact calls that they use to communicate with each other. The frequency of woodcreeper calls is between 840 to 8830 Hz; larger species with longer bills have lower frequency songs.

Woodcreepers sing at dawn and dusk; they sing to mark their territories and to maintain contact with mates. Lekking species sometimes sing in choruses. Geographic variation exists in woodcreeper songs. Different species of woodcreepers are often very difficult to tell apart; many have similar behaviors, colors and shapes. Often they can only be told apart by their calls. (Marantz and Hutson, 2003; Marantz et al., 2003)

Woodcreepers have diverse bill morphologies that reflect their diverse foraging strategies. Some of the foraging strategies include: gleaning, flycatching, probing and chiseling. They often poke through vegetation (including epiphytic plants), pry off bark, and probe along tree surfaces in search of insect prey. Most species find food while climbing on tree trunks or branches. They begin foraging at the base of a tree, work their way up and then fly to the base of another tree and begin again. Some species of woodcreepers forage by following army ant (subfamily Ecitoninae) swarms to catch the prey that are flushed by the swarms.

Woodcreepers are primarily insectivores, although they occasionally eat small vertebrates (such as lizards, frogs, snakes and salamanders), crabs (Decapoda) and snails (Mollusca). The most common foods consumed by woodcreepers include: grasshoppers and crickets (Orthoptera), beetles (Coleoptera), cockroaches (Blattodea), ants (Formicidae) and spiders (Araneae). Only very rarely do woodcreepers eat seeds or fruit. A notable sighting was that of a great rufous woodcreeper (Xiphocolaptes major) eating a small bat. (Campbell and Lack, 1985; Marantz and Hutson, 2003; Marantz et al., 2003; Wetmore, 1972)

Snakes (suborder Serpentes) are common predators of eggs and nestlings. Adults are taken by forest raptors (order Falconiformes). Woodcreepers’ coloration helps them avoid predation by blending in with their habitat. (Marantz et al., 2003; Wetmore, 1972)

Woodcreepers are important members of their ecosystems. They have an impact on populations of the prey they eat and are food for their predators. They are also hosts to a number of blood parasites and feather lice. (Marantz et al., 2003)

There are no known adverse affects of woodcreepers on humans.

Because encounters between woodcreepers and humans are limited, woodcreepers have no direct positive impacts on the economy other than the important ecosystem roles they play. (Marantz et al., 2003)

Habitat fragmentation and destruction for agriculture, logging, mining and the growth of urban areas are the main threats facing woodcreepers. Woodcreepers will not cross large, unforested gaps. This may become a problem for their survival as their habitat becomes increasingly fragmented. The dramatic reduction in lowland forest is also causing a reduction in the number of army ant colonies. Without the army ants, the foraging success of many species of woodcreepers will be reduced. There is a need for more preserves to protect the remaining intact forest.

Some species of woodcreepers are better able to cope with human encroachment than others. For example, some species nest in man-made structures or forage on the insects attracted to lights at night.

The IUCN lists two species of woodcreepers. Moustached woodcreepers (Xiphocolaptes falcirostris) are listed as vulnerable and greater scythbills (Campylorhamphus pucherani) are listed as near threatened. (IUCN, 2003; Marantz et al., 2003)