A Talk on the Wild Side.
|Robert Allen of the Arlington Ecological Services East Texas Sub-office installs an artificial nest cavity for the endangered red-cockaded woodpecker Photo credit: USFWS|
Our Southwest Region's Tom Buckley and Robert Allen tell us about Allen's work as a Surrogate Woodpecker.
Robert Allen, a wildlife biologist at the East Texas Sub-office in Nacogdoches, climbs ladders and builds artificial nest and roost cavities for the endangered red-cockaded woodpecker as part of a recovery effort to enhance nesting habitat in the four national forests in east Texas.
Allen builds these artificial cavities to promote population growth because natural cavity excavation commonly takes several years for the woodpecker to complete.
Unlike other woodpecker species, red-cockaded woodpeckers are highly social and cooperative breeders, living in family clusters comprising the breeding pair and helper males (previous year’s offspring). Most, if not all, red-cockaded woodpeckers in the group have their own cavity, all of which are in live pine clustered in close proximity, hence the term "cluster."
Red-cockaded woodpeckers require open pine woodlands and savannahs with large, old pines for nesting/roosting habitat. Large, old pines are used as cavity trees because the woodpecker excavates completely within the heartwood in order to keep the cavity interior free of the resin the tree produces, which can entrap the birds. Also, old pines are preferred because of the higher incidence of heartwood decay caused by redheart fungus, which makes cavity excavation much easier.
Allen has installed more than 100 artificial cavities by either cutting a rectangular hole in the tree with a chainsaw and pushing a nest box (known as an insert) inside then sealing the edges, or by drilling an entrance tunnel into the tree at a slight upward angle, then drilling down at a 45 degree angle and moving the drill around to create a cavity that is about the size of a 16 oz. beer can (known as a drilled cavity). Both of these types of nests are installed about 30 feet above ground in a pine tree at least 15 inches in diameter. Drilling cavities is much more labor intensive than using the chainsaw method so they are not as commonly used.
After the nest cavity is excavated, Allen scrapes the bark from the tree several feet above and below the cavity. This creates a smooth area around the cavity, making the hole less accessible to black rat snakes. These snakes can slither up the tree and prey on the eggs or chicks, but they find it hard to climb without the bark.
The red-cockaded woodpecker population growth on the national forests in Texas is increasing with every breeding season, and has nearly doubled in the last 10 years to approximately 500 active clusters.