Bald eagles have made a post-DDT comeback — but their return is causing some unexpected eco-issues. A couple months ago, I wrote about how baby bald eagles were finally expected to hatch near me in Santa Cruz Island. Then Peter Sharpe of the Institute of Wildlife Studies followed up with a cute photo of those hatched eaglets. Now, we’ve got bad news about the bald eagle comeback in the Channel Islands (Santa Cruz Island is one of the eight Channel Islands): The birdies might start taking a bite out of other endangered wildlife!
No need to panic yet: Recently recovered species aren’t noshing on not-yet recovered species yet. But researchers behind the report published in the online Proceedings of the National Academy of Sciences say that bald eagles could start snacking on fragile populations of seabirds and island foxes one day. Even worse, they could start feeding on seal or sea lion carrion — which tend to be polluted with contaminants — thus re-polluting the bald eagle population that has just recovered from DDT pollution!
Basically, bald eagles used to eat the carrion of other seabirds — plentiful back before the DDT pollution. But now that food source isn’t so easy to come by. That’s why Seth Newsome, the lead researcher on the study, says a bigger bald eagle population could mean some unexpected bad news: “We think that the introduced eagles could scavenge seal or seal lion carrion, exert predation pressure on a threatened but recovering local seabird population, or even prey on the endangered island fox.”
According to the L.A. Times, this news is based on “an extensive analysis of the shifting diets of the opportunistic foragers from the Pleistocene era, about 20,000 years ago, to the late 1960s.” Old birdie bones show that bald eagles often changed what they ate to adapt to ecosystem changes — which means the newly recovered bird population could start nibbling on island foxes.
If such dangerous nibbling begins, we’ll be sure to notice and report it here at MNN. For now, let's hope for healthy bird populations on the Channel Islands — for the bald eagle and other species — and a happy bounceback for the island fox, too.