Georgia Wild E-Newsletter
Part 1: Rare birds & state lands, DNR's eye is on the sparrow (and warbler)
By Tim Keyes
The State Wildlife Action Plan focuses on species of high conservation concern in Georgia. Some such as bald eagles and wood storks are relatively easy to detect and monitor and have been addressed through existing programs. Others, including some that occur on state property, are more difficult to detect, and their ranges and densities are much less known.
To help provide answers and guide conservation efforts, the Wildlife Resources Division has been surveying state lands for the past three years, primarily for Bachmans sparrow and Swainsons warbler. These two were picked because the extent of their presence on state lands was not known and they respond well to favorable habitat management practices.
Bachmans sparrow and Swainsons warbler represent polar opposites in terms of habitat. Bachmans sparrows are birds of open, grassy, pine savanna habitat, while Swainsons warblers use dense canebrakes and other thickets in bottomland hardwood forests. Bachmans sparrows are year-round residents, which often begin singing in February and continue through August. This makes them relatively easy to hear if not see. Swainsons warblers are neotropical migrants that are rarely seen on migration. They nest earlier than many other migrants and are best surveyed between mid-April and mid-June. Later in the summer they often become much more quiet. All of these characteristics make them significantly more challenging to find.
For both of these species, we use tapes to call for them along transects through suitable habitat. As you can imagine, this is much easier for Bachmans sparrows than Swainsons warblers. It is the difference between strolling through a grassy upland and bushwhacking through dense thickets around bottomland swamps and sloughs.
Generally, Bachmans sparrows are found in upland pine stands that have been thinned and burned. This produces a dense grassy understory with few shrubs and bushes. Frequent fire removes the dead thatch and keeps bushes and hardwoods from taking over. Areas managed for quail typically provide good habitat for Bachmans sparrow, as well. They can be found in regenerating clearcuts for several years when there is a grassy understory before the pine trees close canopy and shade out the grasses.
State lands surveyed for Bachmans sparrow, and the results:
The most promising sites for Bachmans sparrows are in the Coastal Plain, and include the new Silver Lake WMA and River Creek WMA. Many other sites have potential if ongoing thinning and burning maintain suitable habitat.
The surveys for Swainsons warbler included revisiting sites where they had been surveyed in the past. Several sites, such as Cedar Creek WMA and Beaverdam WMA, saw a decline in numbers as the bottomland hardwoods matured, shading out the cane and other understory plants that provide the dense thickets used for nesting. Younger forest stands, such as those found at River Bend WMA South Tract, still maintain very high densities of Swainsons warbler. Yet, even these sites showed signs of the cane becoming light suppressed, leading to some management to remove the overstory in patches and promote the growth of cane.
State lands surveyed for Swainsons warbler, and the results:
While we havent visited all state lands, we have focused on those with the most potential based on known habitat types and requirements for the targeted species. These surveys have allowed us to target areas for management that should help maintain or grow populations of these vulnerable species on state lands.
By managing for these species, we also provide habitat for other species, as well. Many birds and other wildlife are dependent on open pine savanna, including brown-headed nuthatch, loggerhead shrike, Southeastern American kestrel, prairie warbler. Other species using dense bottomland thickets include Kentucky warbler, hooded warbler and white-eyed vireo.
Those who helped with the surveys included Linda Guy, Alan Isler, Walter Lane, Chris Bauman, Brandon Anderson, Bill Blackburn, Allison Reid, Brady Matteson, Nathan Klaus and Charlie Muise.