Causes of Mortality of Red-Cockaded Woodpecker Cavity Trees

Abstract

Over a 13-year period we examined the mortality of cavity trees (n = 453) used by red-cockaded woodpeckers (Picoides borealis) on national forests in eastern Texas. Bark beetles (53%), wind snap (30%), and fire (7%) were the major causes of cavity tree mortality. Bark beetles were the major cause of mortality in loblolly (Pinus taeda) and shortleaf (P. echinata) pines, whereas fire was the major cause in longleaf pines (P. palustris). Cavity trees on the Angelina National Forest (NF) were dying at a higher rate than new, complete cavities were being excavated. Cavity enlargement by pileated woodpeckers (Dryocopus pileatus) on the Angelina NF was substantial, with 20% (49/ 249) of the cavity trees being enlarged over 7 years. To reduce cavity tree mortality, site disturbances in cluster areas (e.g., midstory control, prescribed burning, thinning) should be minimized during years when southern pine beetle (Dendroctonus frontalis) populations are elevated. Careful planning of timber cutting to avoid funneling wind into cluster areas might reduce wind damage to cavity trees.

Tree mortality in a Pinus sylvestris dominated boreal forest landscape in Vienansalo wilderness, eastern Fennoscandia

“…forests in Georgia, USA, where the cause of death of half of the dead trees could not be determined. In a study of dead cavity trees in Texas, USA, Conner et al (1991) reported a similar proportion of 'unknown causes' of tree mortality.…”

Restoration of Southern Pine Forests After the Southern Pine Beetle

“…SPB-induced pine tree deaths may trigger a series of ecological changes (e.g., Conner et al 1991Conner et al , 1998. The SPBrelated tree deaths cause openings in the forest canopy that permit increased light availability in the understory.…”

Proceedings of the Seventh Biennial Southern Silvicultural Research Conference

“…is the major cause of RCW cavity tree loss in Texas loblolly and shortleaf pine stands in Texas , Kulhavy et al 1992. Trees favored by the RCW for nesting and roosting cavities tend to be old, ranging from approximately 60 to 130 years of age in loblolly and shortleaf pine, with slow radial growth, and infection with red-heart rot (Phellinus pini) (Conner and Locke 1982, Conner and O'Halloran 1987, Rudolph and Conner 1991. Such characteristics tend to place pine trees at high risk of attack by southern pine beetles and other phloemboring beetles, even when bark beetle populations are generally at endemic levels.…”

“…The RCW normally excavates cavities totally in heartwood and prefers redheart (PheEZinus pini) heartwood infected trees for easier cavity excavation (Jackson 1977, Conner and Locke 1982, Hooper et al 1991.…”