Archbold Biological Station and Avon Park Air Force Range
Archbold Biological Station (ABS) is contracted by the U.S. Air Force to monitor populations of the federally Endangered Red-cockaded Woodpecker (Picoides borealis; RCW) and Florida Grasshopper Sparrow (Ammodramus savannarum floridanus; FGSP) and the Threatened Florida Scrub-Jay (Aphelocoma coerulescens; FSJ) at the Avon Park Air Force Range (APAFR). The Avian Ecology Program has been studying the FSJ and RCW populations since 1994 and the FGSP population since 2003. The Avian Ecology Program maintains a permanent office and staff at APAFR to monitor these birds so that the impacts of military missions on their populations can be minimized, and to facilitate effective management for their conservation by the Air Force’s natural resources staff. Consistent with the mission of the Avian Ecology Program, we maintain banded populations of all species and, for FSJs and RCWs, find and monitor all nests and conduct periodic censuses of all banded birds. In 2009, Archbold’s Restoration Ecology Lab began a multi-year survey of gopher tortoises at APAFR, and this project also has permanent staff based in our office at the Range.
APAFR is located in Highlands and Polk counties, and at 106,000 acres is one of the largest military training installations in the eastern United States. The primary mission of APAFR is to provide a realistic environment for training American and allied air and ground combat forces. However, the natural habitats found on the Range along with its size and lack of development also make it one of the most significant conservation areas in Florida. APAFR hosts globally rare ecological communities such as cutthroat seeps, Florida dry prairie, and Florida oak scrub, as well as large areas of pine flatwoods, hardwood hammocks, and wetlands. APAFR supports eight animal species federally listed as Threatened or Endangered (including the three birds that Archbold monitors) and two plant species. In addition to its military mission and conservation significance, the APAFR also has active grazing, silviculture, and outdoor recreation programs.
Monitored Bird Species
Red-cockaded Woodpecker (RCW)
Inhabits mature pine flatwoods in the southeastern U.S., nests and roosts in large live pines (almost exclusively longleaf pine (Pinus palustris) at APAFR).
Frequent fires necessary to prevent encroachment by oaks or other hardwoods and maintain high quality RCW foraging habitat.
Nest cavity excavation can take several years; resin flow around entrance thought to be a defense against predation by snakes.
Family groups reside in aggregations of cavity trees called clusters. Even after reaching adulthood, young males will often stay with their parents and help to raise younger siblings.
Management at APAFR: The ABS office monitors RCW activity in all clusters at APAFR and collects data on population size and distribution, as well as demographic traits such as reproductive success and survivorship. All birds in the population are uniquely banded with color bands and are censused periodically. In addition, we monitor the status of all cavity trees and install and maintain artificial cavity inserts. Because RCWs can take several years to complete one cavity, installing artificial cavities can provide additional options for nesting and shelter and should allow the population to expand and recover faster. APAFR also is a member of the Southern Regional Translocation Cooperative for RCWs, and ABS periodically conducts translocations of young birds from larger populations into APAFR as a way of speeding population growth. Current research projects focus on factors affecting long-term demographic patterns in the population, particularly those affecting source-sink dynamics and nesting success.
The RCW population at APAFR appears to be limited by the production and recruitment of females, rather than males.
Restricted to large expanses of dry prairie, a habitat type which has been highly fragmented and reduced by more than 90% since European settlement of Florida.
Frequent fires are required to maintain high quality nesting habitat.
Appears to avoid forested areas, to the extent that prairie habitat within ~400 m of a forested edge is avoided and encroachment of woody vegetation, as a result of fire suppression, into dry prairie can turn source habitats into sinks.
Management at APAFR: ABS conducts point count surveys for FGSPs in dry prairie habitat at APAFR during the breeding season (April – August) in order to estimate their numbers and distribution. We monitor success of all nests that we find (although the number found each year is relatively small given their cryptic nature), and color band birds to monitor their movements and survival rates. As part of a project supported by the U.S. Fish and Wildlife Service, we have used data from all three FGSP populations to develop occupancy models that provide a better understanding of sparrow habitat preferences. We have also recently published research on the metapopulation structure of the FGSP, as well as the potential relationship between cattle grazing in FGSP habitat and nest predation caused by imported red fire ants. Ongoing research includes the effects of trampling by cattle on nests and breeding phenology.
Florida Scrub-Jay (FSJ)
Endemic to oak scrub habitat in central Florida, probably fewer than 10,000 remain.
Habitat maintenance requires fire, but favors habitat in intermediate stages of succession; in most areas the best conditions for FSJs occur from about 5 – 20 years following a fire. FSJs prefer areas with low canopy height and large amounts of bare exposed soil.
Acorns are an important food for winter survival. FSJs will cache thousands of acorns each year by burying them in patches of bare sandy soil. Their spatial memory is excellent and allows them to recover most of these caches.
Like the RCWs, FSJs are also cooperative breeders. Birds of both sexes will stay on their parents’ territory and help raise younger siblings until breeding opportunities become available.
Management at APAFR: ABS conducts quarterly censuses of the FSJ population at APAFR in order to determine its size and distribution, and to assess survival rates. We have marked the entire population with color bands to better monitor and study them. During the nesting season, we find all FSJ nests on the Range so that disturbances from training and management activities can be minimized. Current research is particularly focused on gaining a better understanding of FSJ dispersal behavior, especially in patchy, fragmented landscapes where the surrounding matrix habitat types vary in their permeability to FSJ movements.
The matrix of habitat types at APAFR include those that facilitate and deter dispersal by FSJs