LOSSES OF RED-COCKADED WOODPECKER CAVITY TREES TO SOUTHERN PINE BEETLES

Over an 11-year period (1983-1993), we examined the southern pine beet le (Dendroctonus frontalis) infestation rate of single Red-cockaded Wo odpecker (Picoides borealis) cavity trees on the Angelina National For est in Texas. Southern pine beetles infested and killed 38 cavity tree s during this period. Typically, within each cavity tree cluster, beet les infested only a single tree (usually the nest tree of the previous spring) during autumn and used the cavity tree as an over-wintering s ite for brood development. Seven (4 active and 3 inactive) cavity tree s (out of 346 cavity tree years) died as a result of beetle infestatio n during the first five years of the study (1983-1987). In 1988, an in tensive habitat management program was initiated on the forest to halt a severe population decline of the woodpecker. During the next six ye ars (1988-1993), a much higher mortality rate was observed; 31 single cavity trees (out of 486 cavity tree years) were infested and killed ( chi(2) = 8.8, P < 0.003). Southern pine beetle-caused mortality of cav ity trees also was high on other Texas national and state forests duri ng this period. This marked increase of beetle-caused cavity tree mort ality during a period of increased intensity of necessary management i s of extreme concern. As a result of high beetle-caused mortality of a ctive cavity trees, 64% of active cavity trees being used by Red-cocka ded Woodpeckers on the northern portion of the Angelina National Fores t during 1993 were artificial cavities. Pines selected by biologists f or cavity inserts may produce less resin than those selected by woodpe ckers and not provide an adequate barrier against snakes. The relation ship between infestation of single active cavity trees and the number of beetle infestations (spots) on the northern portion of the Angelina National Forest from 1984 to 1993 was inconclusive (r = 0.56, P > 0.0 9, N = 10); further research is needed for a definitive conclusion.