A high-powered nest box project in Georgia is helping North America's smallest falcon.

Southeastern American kestrels, a subspecies of the falcons often called sparrowhawks, declined an estimated 80 percent over the last half of the 20th century. The main culprit is habitat loss, including fewer suitable cavities for nesting.

Of Georgia's breeding populations, the largest is along a transmission line reaching west from Pierce County, through Tifton to Georgia Power Co.'s Plant Mitchell near Albany. Georgia Southern University research showed that hollow cross-arms on the power poles provide critical nest sites ("Power in towers for kestrels," January-February 2008). However, the hollow cross-arms are gradually being replaced as they rust with solid ones.

In response, for almost 10 years Georgia Power has put up a nest box each time one of the cross-arms is replaced, said Jim Candler, company environmental affairs supervisor. "As these things wear out, we agreed it was important enough for us to figure out how not to eliminate that (nesting) habitat."

Some 30 boxes have been added. And while nest boxes (example at left) are more vulnerable to predators than a cross-arm far above the ground, DNR Nongame Conservation Section surveys marked an average 17 percent annual increase in the Tifton line population, and an estimated 302 nesting pairs in 2014.

DNR senior wildlife biologist Nathan Klaus is interested in applying survey data to fine-tune where boxes are placed. "Using nest box and helicopter surveys to develop models, we've almost tripled our rate of box use" in Fall Line sandhills populations of southeastern kestrels, Klaus said.

He's also hopeful that a proposed nest box program, coupled with habitat restoration in the region, could help save a dwindling population of kestrels that is down to about 25 breeding pairs along a Macon-Columbus transmission line owned by another company.