Richard R. Schaefer

AVIAN COMMUNITY RESPONSE TO SOUTHERN PINE ECOSYSTEM RESTORATION FOR RED-COCKADED WOODPECKERS

Abstract The effects of Red-cockaded Woodpecker (Picoides borealis) management on nontarget birds is not widely known. Intensive management for pine specialists such as the Red-cockaded Woodpecker may negatively impact both Nearctic-Neotropical and Temperate Zone migrants associated with hardwood vegetation. To evaluate possible positive and negative associations, we surveyed avian communities from 1995–1997 using point counts within managed Red-cockaded Woodpecker cavity tree clusters and mature forest control sites in longleaf pine (Pinus palustris) and loblolly (P. taeda)-shortleaf (P. echinata) pine habitats. In general, sites managed for Red-cockaded Woodpeckers supported more diverse and numerous bird populations than mature forest control sites. During the breeding season in loblolly-shortleaf and longleaf pine habitats, respectively, species richness was 47% and 23% greater, avian abundance was 57% and 65% greater, and bird species diversity was 25% and 21% greater within managed Red-cockaded Woodpecker cluster sites than within control sites. During winter, species richness and avian abundance each were 52% higher within managed Red-cockaded Woodpecker cluster sites than control sites in loblolly-shortleaf pine habitat.

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,

Group size and nest success in Red-cockaded Woodpeckers in the West Gulf Coastal Plain: helpers make a difference

Abstract We studied the relationships between Red-cockaded Woodpecker (Picoides borealis) group size and nest productivity. Red-cockaded Woodpecker group size was positively correlated with fledging success. Although the relationships between woodpecker group size and nest productivity measures were not statistically significant, a pattern of increasing clutch size and number of hatchlings with increasing group size was apparent. The presence of helpers appeared to enhance the survival of nestlings between hatching and fledging. The contribution that helpers make to nestling feeding and incubation, cavity excavation, and territory defense appears to have a positive effect on nest productivity. A threshold number of helpers may be necessary before a significant benefit for fledging success is realized. Nests with four and five group members fledged more young than nests with two or three group members. Whether partial brood loss occurred or not within a nest was primarily a function of clutch size and the number of hatchlings. Although partial brood loss did affect the number of young fledged from individual nests by removing young from nests with high numbers of hatchlings, woodpecker group size appeared to be the primary determinant of fledging success.

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.

Red-cockaded woodpecker nestling provisioning and reproduction in two different pine habitats

Abstract We obtained nestling provisioning and reproductive data from 24 Red-cockaded Woodpecker (Picoides borealis) groups occupying two different pine habitats—longleaf pine (Pinus palustris) and a mixture of loblolly (P. taeda) and shortleaf pine (P. echinata)—in eastern Texas during 1990 and 1991. Habitat data were collected within 800 m of each groups cavity-tree cluster. Feeding trips per nest and prey biomass per feeding trip were significantly greater in loblolly-shortleaf pine habitat. There were few significant correlations between reproductive/provisioning and habitat variables in either pine habitat. Pines dying from infestation by southern pine beetles (Dendroctonus frontalis) were more common in loblolly-shortleaf than in longleaf pine habitat. In addition, adult male Red-cockaded Woodpeckers weighed more in loblolly-shortleaf pine habitat. Indices of southern pine beetle abundance in loblolly-shortleaf pine habitat were negatively correlated with number of feeding trips per nestling, but positively correlated with prey biomass delivered to nestlings. We hypothesize that the greater abundance of southern pine beetles and associated arthropods in loblolly-shortleaf pine habitat, and the resulting higher frequency of dying pines containing an abundant food source, were associated with an elevated prey biomass available to both nestling and adult Red-cockaded Woodpeckers.

Status of Pituophis ruthveni (Louisiana Pine Snake)

Abstract Extensive trapping surveys across the historical range of Pituophis ruthveni (Louisiana Pine Snake) suggest that extant populations are extremely small and limited to remnant patches of suitable habitat in a highly fragmented landscape. Evaluation of habitat at all known historical localities of P. ruthveni documents the widespread degradation of the fire-maintained pine ecosystem throughout the historical range of the species. The primary factors leading to degradation of P. ruthveni habitat are intensive pine silviculture and alteration of the pre-European fire regime. Habitat restoration on public lands is feasible and could potentially restore populations of this critically rare species.

Does the availability of artificial cavities affect cavity excavation rates in red-cockaded woodpeckers?

Abstract Rates of cavity excavation by Red-cockaded Woodpeckers (Picoides borealis) were examined from 1983 to 1999 on the Angelina National Forest in east Texas. We compared the rate of natural cavity excavation between 1983 and 1990 (before artificial cavities were available) with the rate of cavity excavation between 1992 and 1999, a period when artificial cavities were regularly installed within active woodpecker cavity-tree clusters. Our comparison was restricted to cavity-tree clusters in longleaf pine (Pinus palustris) and loblolly (P. taeda)-shortleaf (P. echinata) pine habitats where woodpecker groups were present for the entire period between 1983 and 1999. Excavation rate of new cavities was significantly higher in longleaf pine habitat when artificial cavities were not available than during the subsequent period when artificial cavities were provided in all active cavity-tree clusters. In loblolly-shortleaf pine habitat, we did not detect a significant difference in the rate of new cavity excavation between the periods before and after the use of artificial cavities. We attribute the difference in results between habitats to a relative scarcity of cavities in loblolly-shortleaf pine sites due to a higher bark beetle-induced cavity tree mortality.

Interactions Between Nesting Pileated Woodpeckers and Wood Ducks

Abstract We observed interactions between a nesting pair of Pileated Woodpeckers (Dryocopus pileatus) and what appeared to be four pairs of Wood Ducks (Aix sponsa). Wood Ducks regularly approached and attempted to enter an active Pileated Woodpecker nest cavity that contained three fully feathered young Pileated Woodpeckers. The male Pileated Woodpecker often perched on a snag near their nest cavity to guard the entrance from Wood Ducks. Female Wood Ducks attempted to enter the Pileated Woodpecker nest cavity on at least 12 occasions and typically were intercepted by the male Pileated Woodpecker before they reached the lip of the nest cavity. On two occasions the male Pileated Woodpecker entered his nest cavity and forcibly evicted female Wood Ducks that had slipped into the cavity. These incidents suggest that large cavities in snags may be in high demand by Wood Ducks during the nesting season. Our observations suggest that some Pileated Woodpeckers may be able to resist attempts by Wood Ducks to usurp nest cavities during the breeding season.

A Red-cockaded Woodpecker Group with Two Simultaneous Nest Trees

Abstract During a study of Red-cockaded Woodpecker (Picoides borealis) nesting in eastern Texas, we discovered a single breeding pair of woodpeckers with two simultaneous nests in nest trees that were 24 m apart. Incubation of eggs in each nest tree was at least 13 d and may have been as long as 16 d. The breeding male incubated and fed a nestling in one nest tree and the breeding female incubated and fed a nestling in the other nest tree until the nestlings were ≥24 d old. Prior to fledging, both the breeding male and female were observed feeding both nestlings in both nest trees. The pair successfully fledged the two nestlings, a single fledging from each nest tree, during one nesting cycle. After the nestlings were fledged, both the male and female woodpeckers were observed feeding both fledglings about 350 m from the pair of nest trees. Our observations indicate that there are exceptions to the current theory that the contribution by the breeding male and female to incubation and feeding of nestlings is essential and that neither the male nor the female can normally rear young birds without the contribution of the other.