Determination of the Status of Red-Cockaded Woodpecker Colonies

Abstract

The red-cockaded woodpecker (Picoides borealis) is an endangered species endemic to mature, open pine (Pinus spp.) forests of the southeastern United States. The cavity trees of this species are conspicuous and, because they are always living pines, they remain long after the birds occupying them have left or died. For this reason and others, estimates of this species' abundance are often inflated by observers using the presence of cavity trees as indicative of the presence of the birds. This paper discusses characteristics of cavity trees that are being used by red-cockaded woodpeckers and that can be used by forest or wildlife managers as evidence of the species' presence. J. WILDL. MANAGE. 41(3):448-452 The red-cockaded woodpecker is an endangered species endemic to mature, open pine forests of the southeastern United States (Jackson 1971, U.S. Department of the Interior 1973). Forest and wildlife managers frequently are asked to identify its presence and status on lands under their stewardship. Discovery of an active nest is, of course, the surest way to determine the species' breeding status in an area, and seeing the birds is proof enough of their presence. Unfortunately, these woodpeckers may forage 2 km or more from their cavity trees and be absent from the cavity tree area (colony: see Jackson and Thompson (1971) for definitions of terms used in reference to the red-cockaded woodpecker) for several hours at a time unless there are eggs or young in the nest. The cavity trees of red-cockaded woodpeckers are generally obvious (Fig. 1) and are often used as indication that the species is present. Cavity trees are almost always living pines (1 bald cypress (Taxodium distichum) cavity tree was discovered in South Carolina). The woodpeckers eventually remove bark from around the cavity entrance to form what is referred to as a plate and they excavate small holes-resin wells-into the cambium around and often for 2 m or more above and below it. As some of the gum dries, it turns white and the cavity trees can be seen for some distance. The presence of the pine gum around the cavities has been demonstrated to be an effective barrier against climbing rat snakes (Elaphe obsoleta) (Jackson 1974). The purpose of his paper is to describe characteristics of active cavity trees and to discuss characteristics that can be used to determine the status of a red-cockaded woodpecker col-