Comeback of bald eagle population in Ohio is monumental

The announcement timed for Independence Day that Ohio held 964 active bald eagle nests during spring drew much media attention.

The interest shown and the notice sought by the Ohio Division of Wildlife was warranted, said Mark Shieldcastle, one of the architects of the comeback.

Keep in mind that about 60 years ago only 417 nesting eagle pairs could be found in the entire United States outside of Alaska. The current Ohio reckoning more than doubles national numbers during those darker days when the national bird seemed headed for oblivion.

By the late 1970s all of four nests – none guaranteed to produce young – were bunched in northwestern Ohio along Lake Erie.

At that time Denis Case, who became a longtime wildlife biologist with the wildlife division after helping jettison his previous post as director of research for the Ohio Department of Natural Resources, put a program in motion based on the belief that eagles could and should be saved.

“I think we’d reached a point that if we hadn’t done something we would’ve lost eagles in Ohio,” said Shieldcastle, back then a wildlife division biologist who initially helped implement the restoration effort and after a time headed it.

These days Shieldcastle is director of research at the Black Swamp Bird Observatory in Ottawa County, only a wing flap from Crane Creek Wildlife Area where he directed eagle efforts until he retired in 2012.

The early eagle crew also included Denis Franklin, nowadays a supervisor with Metroparks Toledo, and tree climber Todd Haines, currently an assistant chief with the wildlife division.

Hundreds of volunteers and spotters have helped over the years.

The labor-intensive work involved such hazardous duty as scaling tall tree trunks to observe soaring nests, banding and health-checking adults, moving hatchery fledglings to nests of adoptive eagle couples watching over unhatched eggs or doomed nestlings and constructing platforms in trees better suited to nest-building than more fragile trees eagles had chosen themselves.

The platforms encouraged eagles to vacate nests in sky-stretching but brittle cottonwoods, for example, and rebuild on the platforms in oaks and hickories, ensuring longer and safer occupancy. Also helpful was that many of Ohio’s eagles, incapable of hatching their own eggs made frail by toxicity, would readily adopt fledgling birds placed in the nests at the proper time.

“Our eagles weren’t good producers,” Shieldcastle said, “but they were good parents.”

Legislation helped save eagles, although the inspiration behind an environmental awakening can be traced to 1962 book "Silent Spring" by Rachel Carson that revealed the extent to which chemical use was harming living things.

The widely used pesticide DDT was banned after it was linked to the inability of eagles, hawks, falcons and brown pelicans to produce eggshells sturdy enough for nest maneuvering. Eventually, it was discovered that commonly used compounds known as PCBs also were impacting eagles by causing hormonal disruptions that interfered with reproduction.

Jefferson, a bald eagle, looks into the distance June 24 at the Howell Nature Center in Michigan.

The problem became especially serious around bodies of water where runoff from land could bring in toxic residues taken up by fish and bioaccumulate in species that eat fish, as do bald eagles.

Once use of such chemicals ceased the toxicity didn’t evaporate, but eventually the brew did get buried and trapped in sediment out of harm’s way.

Had efforts not started when they did, Shieldcastle guesses, recent eagle news might not be as cheery.

“I think what we did was buy them time to adapt,” he said. “We used to think they needed pristine conditions, isolated nests. But we see now they can tolerate people.”

Which actually is saying a lot.