The red-cockaded woodpecker: interactions with fire, snags, fungi, rat snakes and pileated woodpeckers
Red-cockaded woodpecker (Picoides borealis) adaptation to fire-maintained southern pine ecosystems has involved several important interactions: (1) the reduction of hardwood frequency in the pine ecosystem because of frequent tires, (2) the softening of pine heartwood by red heart fungus (Phellinus pini) that hastens cavity excavation by the species, (3) the woodpecker's use of the pine's resin system to create a barrier against rat snakes (Elaphe sp.), and (4) the woodpecker as a keystone cavity excavator for secondary-cavity users. Historically, frequent, low-intensity ground tires in southern pine uplands reduced the availability of dead trees (snags) that are typically used by other woodpecker species for cavity excavation. Behavioral adaptation has permitted red-cockaded woodpeckers to use living pines for their cavity trees and thus exploit the frequently burned pine uplands. Further, it is proposed that recent observations of pileated woodpecker (Dryocopus pileatus) destruction of red-cockaded woodpecker cavities may be related to the exclusion of fire, which has increased the number of snags and pileated woodpeckers. Red-cockaded woodpeckers mostly depend on red heart fungus to soften the heartwood of their cavity trees, allowing cavity excavation to proceed more quickly. Red-cockaded woodpeckers use the cavity tree's resin system to create a barrier that serves as a deterrent against at snake predation by excavating small wounds, termed resin wells, above and below cavity entrances. It is suggested that red-cockaded woodpeckers are a keystone species in fire-maintained southern pine ecosystems because, historically, they were the only species that regularly could excavate cavities in living pines within these ecosystems. Many of the more than invertebrate and invertebrate species known to use red-cockaded woodpecker cavities are highly dependent on this woodpecker in fire-maintained upland pine forests.