PHOENIX – For three years a pair of bald eagles nesting along the Verde River continued to return to the only nest they had ever known. And each year their eaglets died, despite the efforts of biologists.
After determining that the tree and nest were the problem, eagle management officials with the Arizona Game and Fish Department destroyed the old nest and painstakingly constructed two new nests in neighboring trees, hoping the eagles would adopt one as a new home.
The result: Two nestlings from that man-made nest made it all the way through fledging this year.
“It was real exciting, after three years of trying to get these nestlings to survive,” said Kenneth Jacobson, eagle management coordinator for Game and Fish. “We finally were able to see these birds do it on their own.”
The artificial nest demonstrates the continued success of the Game and Fish eagle management and nest watchers programs, according to Jeff Humphrey, a spokesman for the U.S. Fish and Wildlife Service.
“Intensive management is needed in some species,” Humphrey said. “We are just happy Game and Fish was there in this instance.”
Game and Fish launched its program in 1978, when Arizona had only 11 breeding pairs of bald eagles and the state population was on the verge of extinction.
This year, 54 breeding pairs laid more than 80 eggs, and 52 eagles successfully left the nest.
Three years ago, on the Salt River Pima-Maricopa Indian Community land east of Phoenix, Game and Fish received a call about two eaglets that had fallen from their nest.
“We took the birds into rehab to see if we could nurse them back to health, but we were unsuccessful,” Jacobson said.
In the process, Game and Fish officials discovered that the “Orme” eaglets were infested with tick larvae that was slowly killing them.
The following year a biologist noticed the tree branch holding the nest looked like it had been infested with termites and now served as a hideout for ticks.
The adult eagles, however, continued to return to the nest each season, unaware the nest was the cause of the death of their young.
“From the time that we found the ticks, we tried several things to get rid of them,” Jacobson said.
Officials tried bird-safe pesticides to treat the eagles. When that failed, Jacobson said, the following season they unsuccessfully tried to treat the tree.
“That’s when we decided to stop trying to remove the ticks and remove the nest completely and get the adults to nest in a different tree,” Jacobson said.
Bald eagle nests can be up to 7 feet wide and weigh as much as 2,000 pounds, and Game and Fish officials built two, hoping the adult eagles would choose one.
Environmental groups and state officials have wrangled over the bald eagle’s status because, while the Arizona population still receives federal protection under the Bald and Golden Eagle Protection Act, it was removed from the endangered list last year.
Robin Silver, co-founder of the Tucson-based Center for Biological Diversity, said that eight bald eagle nestlings dying over three years is an indication of a larger problem.
“Long term this is not a viable solution,” Silver said. “There is not enough habitat for the birds to survive long term.”
Matthew K. Chew, a research faculty associate with Arizona State University’s Center for Biology and Society, said human intervention isn’t an unprecedented way of helping a species.
“But from the birds point of view, it worked,” Chew said. “So, for the real Darwinian meaning of fixing this nest, they are breeding again whereas before they were not.”