D. Craig Rudolph

Causes of mortality of red-cockaded woodpecker cavity trees

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. The red-cockaded woodpecker has been legally defined as an endangered species since 1970 (35 Fed. Register 16047, 13 Oct 1970). A habitat feature that is essential for the survival 0~ this species is a constant supply of living, old Ptnes with decayed heartwood (Jackson 1977, Conner and Locke 1982) and large crowns and open boles that have had some suppression in their growth history (Conner and OHalloran 1987). The woodpecker excavates nest and roost ~~ies. in these trees (U.S. Fish W ildl. Serv. S • Lrgon et al. 1986). In the southern United tates old · f h 1 . Cos pmes o t IS type are re atlvely rare. . ta and Escano (1989) indicated that suffictentl ld . sho Y 0 pmes for cavity excavation are in So ~supply on many national forests in the is ut and that the age structure of most forests lo~u~h that supply of old pines is likely to be lions ; >20 years. Recent declines in populaRudo~ ~ed-cockad.ed woodpeckers (Conner and lack r 1989) might be caused in part by a 0 old-growth pines in southern pine forests. J. WILDL. MANAGE. 55(3):531-537 Thus, to develop management options that reduce the loss of cavity trees, it is important to identify factors causing this loss. In our study, we evaluate mortality of cavity trees used by red-cockaded woodpeckers and suggest management options to reduce losses. We thankS. C. Loeb, P. Lorio, R. W. Mannan, F . L. Oliveria, and J. R. Walters for constructive comments on an early draft of the manuscript. Partial funding was provided by a Challenge Cost Share Agreement (#19-90-008) with the Resource Protection Division, Texas Parks and Wildlife Department.

Red-Cockaded Woodpecker Foraging Behavior in Relation to Midstory Vegetation

Abstract Red-cockaded Woodpeckers (Picoides borealis) nest and forage in pine-dominated forests. Research indicates that substantial hardwood midstory encroachment is detrimental to Red-cockaded Woodpecker populations, although the exact mechanisms are unknown. We examined foraging behavior in relation to midstory between August 1989 and February 1990. Red-cockaded Woodpeckers foraged at greater heights in areas of taller and denser midstory in the loblolly-shortleaf pine (Pinus taeda and P. echinata, respectively) habitat, but not in longleaf pine (P. palustris) habitat with less-developed midstory vegetation than typical of loblolly-shortleaf pine habitat. In addition, Red-cockaded Woodpeckers concentrated foraging activities in or adjacent to forest stands or openings with reduced midstory vegetation. Overall, Red-cockaded Woodpeckers foraged disproportionately at heights and sites that minimized their exposure to dense midstory conditions. These results suggest that ecosystem management, preferably using prescribed fire, that reduces midstory vegetation will improve foraging habitat for Red-cockaded Woodpeckers.

Experimental Reintroduction of Red-cockaded Woodpeckers

The Red-cockaded Woodpecker (Picoides borealis) is an endangered species endemic to the pine forests of the southeastern United States (Jackson 1971). Deforestation and habitat alteration have severely affected Red-cockaded Woodpecker populations; current populations are isolated and most are declining (Jackson 1971, Lennartz et al. 1983, Conner and Rudolph 1989, Costa and Escano 1989). The species has been extirpated from significant areas of suitable or potentially suitable habitat. The cooperative-breeding social structure (Ligon 1970, Walters et al. 1988) and the dependence on the availability of adequate roost and nest cavities (Walters et al. 1992) strongly influence the biology of the species. A direct consequence of this social structure in remnant populations is the demographic collapse resulting from the failure of or extended lag time involved in the natural replacement of breeding individuals. This effect becomes increasingly severe as individual woodpecker groups become more isolated in the declining populations (Conner and Rudolph 1989). Potentially, the recently available techniques of artificial cavity construction (Copeyon 1990, Allen in press) and translocation of first-year adults (DeFazio et al. 1987) have provided managers with the ability to minimize this problem. A major void in management procedures is the current lack of a technique to artificially establish woodpecker groups and populations de novo. Previous efforts to relocate Red-cockaded Woodpecker breeding pairs met with limited success (Odom et al. 1982, Jackson et al. 1983). The recent improvements in cavity-construction techniques and experience in translocating individual birds convinced us that it was time to revisit the issue of the reintroduction of breeding pairs to vacant habitat. An inactive cluster of cavity trees on the Davy Crockett National Forest in eastern Texas was chosen for the attempt. The site had been inactive for about two years. The site contained two natural cavities. One had a metal restrictor to reduce the enlarged entrance (Carter et al. 1989), and the other was a single artificial cavity (insert type). Cavity competitors, flying squirrels (Glaucomys volans) and Red-bellied Woodpeckers (Melanerpes carolinus), were removed as necessary before and during the reintroduction. Resin wells were reopened using a wood chisel prior to introduction of the birds. The chosen site was approximately 3.5 km from the nearest woodpecker group, which consisted of a breeding pair and a helper male. All three birds were color banded, and the helper had joined the pair during the previous six months. The helper male was known to have visited the reintroduction site at least once prior to the reintroduction. Due to the familiarity of this helper male with the site, we elected to use him as the reintroduction male. The reintroduction female was a bird of unknown origin associating with a male/female pair on the Davy Crockett National Forest. Eight additional clans were located within 10 km of the reintroduction site. Standard translocation techniques (DeFazio et al. 1987) were employed. Briefly, the birds were netted from their roost cavities, transported in mesh cages, and placed in a natural cavity (male) and insert (female) on the night of 17 February 1991. The respective cavity trees were approximately 20 m apart. Wire mesh was tacked over the entrances to contain the birds until dawn. A nylon cord attached to the mesh allowed the birds to be released by a person stationed at the base of each cavity tree. The birds were released simultaneously at dawn on 18 February. The birds immediately established vocal and visual contact, and remained in the immediate area for approximately 30 min. During this period, vocalizations and following behavior were similar to that which we have come to associate with successful translocations of juvenile birds to an established mate. It started to rain at this time, and we left the site. The two birds returned to the site on the evening of 18 February and roosted in the immediate vicinity, but not in the cavities. The birds were next checked on the evening of 20 February. The female was still present and roosted in the open. The male had returned to his original group and was roosting in his original cavity. Rather than relocate the male a second time, or depend on his voluntary return, we decided to obtain a second male. During the night of 21 February, we translocated a juvenile male (fledged 28 May 1990) from his natal group on the Angelina National Forest, Texas. The male was released from the introduction cavity shortly after the female became active on the morning of 22 February. Due to the distance (150 m) between the roost site of the female (still roosting in the open) and the introduction cavity for the male,

RED-COCKADED WOODPECKER NEST-CAVITY SELECTION: RELATIONSHIPS WITH CAVITY AGE AND RESIN PRODUCTION

We evaluated selection of nest sites by male Red-cockaded Woodpeckers (Pi- coides borealis) in Texas relative to the age of the cavity when only cavities excavated by the woodpeckers were available and when both naturally excavated cavities and artificial cavi- ties were available. We also evaluated nest-cavity selection relative to the ability of naturally excavated cavity trees to produce resin, which is used by the woodpeckers to maintain a barrier against predation by rat snakes (Elaphe spp.). Longleaf pines (Pinus palustris) selected by breeding males as nest trees produced significantly greater resin yields at 2, 8, and 24 h post-wounding than cavity trees used for roosting by other group members. This preference was observed in loblolly pine (I! taeda) and shortleaf pine (I? echinata) cavity trees only at the 2-h resin-sampling period. When only naturally excavated cavities were available, Red-cock- aded Woodpeckers in both longleaf pine and loblolly-shortleaf pine habitat selected thenew- est cavities available for their nest sites, possibly as a means to reduce parasite loads. When both naturally excavated and artificial cavity inserts were available, Red-cockaded Wood- peckers continued to select the newest cavity for nesting in loblolly-shor tleaf pine habitat but not in longleaf pine habitat. Resin production in existing longleaf pine nest trees re- mained sufficient for continued use, whereas resin production in loblolly pine and shortleaf pine nest trees decreased through time, probably because of woodpecker activity at resin wells. For these latter tree species, breeding males switched to newer cavities and/or cavity trees with higher resin yields. Received 7 )uly 1997, accepted 11 November 1997.

RED-COCKADED WOODPECKER FORAGING BEHAVIOR

Abstract We studied Red-cockaded Woodpeckers (Picoides borealis) to examine the effect of status and gender on foraging behavior. Foraging behavior of breeding pairs extended beyond separation by foraging height to include zones (bole, trunk in crown, primary limb, secondary limb) of the tree used and foraging methods (scaling, probing, excavating). Helper males and juvenile females maintained partial spatial separation from breeding adults. Helper males maintained spatial separation from breeding adults by exploiting limbs within tree crowns in both longleaf (Pinus palustris) and loblolly-shortleaf (P. taeda, P. echinata) pine forests, but also increased use of boles in loblolly-shortleaf pine in concert with reduced use of boles by adult females. Breeding males tended to forage less by scaling, probably due to the reduced proportion of foraging on boles of trees where scaling tends to predominate.