The Potential of Girdled and 2,4-D-Injected Southern Red Oaks as Woodpecker Nesting and Foraging Sites

Comparisons of extent of decay in southern ed oaks (Quercus falcata M ichx.) revealed that rees injected with 2,4-D decayed sooner than girdled trees. Internal examinations of treated trees revealed that girdling and injection permitted growth of heartwoodand sapwood-decaying fungi, a condition necessary for woodpecker n st cavity excavation. Asa result of the delayed ecay, girdling produces better woodpecker habitat in southern red oak. Girdled southern red oaks remain standing longer for woodpeckers to use as foraging and nesting sites. Numbers of snags required to support various percentages of woodpecker population maximums are presented. Woodpeckers are an important component of forest ecosystems. They feed regularly on insects that damage both pines and hardwoods (Kroll et al. 1980) and provide cavities for many other wildlife species (Evans and Conner 1979). Important problems in woodpecker management are determining how many snags woodpeckers require for nesting and foraging, and how these snags can be provided. Girdling or herbicide injection of hardwood trees during timber stand improvement (TSI) creates dead trees suitable as nesting and foraging sites for woodpeckers. Conner et al. (1981) examined the fruiting bodies (conks) of fungi that fruited on four species of 2,4-D-killed hardwood trees in east Texas. They determined that the herbicide did not prevent heartwoodand sapwood-decaying fungi from growing in the trees, but they did not determine if the trees were sufficiently decayed for woodpecker nest cavity excavation. Woodpeckers require a decayed heartwood in hardwood trees in order to excavate next cavities (Conner et al. 1976). Preliminary observations also suggested that trees injected with the herbicide fell sooner (three to four years) than trees killed by natural causes, making them of only short-term use for cavity nesters (Conner et al. 1981). Any snag, such as an injected or girdled tree, that has a decayed heartwood is a potential cavity site for woodpeckers (Conner 1978). All snags are also important as foraging substrata for woodpeckers during all stages of decay (Evans and Conner 1979). We compared the internal conditions of both 2,4-D-injected and girdled southern red oaks to determine which TSI technique would best create trees suitable for woodpecker nest sites.