Bald Eagles: Incredible Avian Engineering

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This Bald Eagle, a rehabbed bird, is from Mercer County Wildlife Center. She was photographed last month at a presentation abut Bald Eagles at the Tulpehaking Nature Center in Hamilton.

Written By: Jim Wright for Duke Farms and Conserve Wildlife Foundation

Screen Shot 2015-04-01 at 8.56.14 AMOur story thus far:  The Bald Eagles incubated two eggs this season. Both eaglets have hatched within the past week. You can view the nest on streaming video here.

The eaglets in the Duke Farms nest look so fragile and helpless that it’s hard to believe that, if all goes well, in the next few months they will grow into enormous raptors with incredible abilities. (Photo at right was taken this morning via the Eagle Cam.)

Bald Eagles not only build the largest bird’s nests in the world, but as viewers of the Duke Farms Eagle Cam have seen, they are able to incubate their eggs in all sorts of snowstorms and Arctic blasts.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            These alpha predators, sitting atop the food chain, have incredible eyesight as well.

“Their visual acuity is four to six times better than a human’s,” says Bill Streeter, director of the Delaware Valley Raptor Center in Milford, Pa. “That’s similar to or slightly better than other diurnal raptors, better than most other birds.”

Bill, a raptor rehabilitator and educator who has worked with Bald Eagles for more than three decades, says great vision goes with the territory:   “With some exceptions — bats, sharks and pit viper snakes come to mind — most predators must have great eyesight.”

Bald Eagles also have very good hearing, says Bill. “Their hearing is less important than eyesight and probably less important than that of smaller raptors who are preyed upon by larger raptors and other animals. Still, it’s hard to sneak up on a bird of prey without them hearing you.”

Where are the ears located? “Small hole on the side of the head slightly behind and above the back ‘lip’ area of the mouth, according to Bill.

Despite all their strengths, Bald Eagles do have a couple of weaknesses. “Like most raptors, they don’t have a great sense of smell,” Bill says.colbert eagle

And their voice is nothing to write home about. The call generally associated with a Bald Eagle — think of the opening of the old  “Colbert Report”  on Comedy Central — actually belongs to a Red-tailed Hawk.

You can listen to their calls here (courtesy of the Cornell Lab of Ornithology).

For more information on Bald Eagles’ vision, Bill suggests reading “The Eyes Have It” section of  “Raptor Adaptations” by Stephanie Streeter (his wife and fellow raptor rehabilitator) on their website.

Got a question or suggestion? E-mail Jim at wrightjamesb@gmail.com

Jim Wright writes “The Bird Watcher” columnist for The Record and the Herald-News. He is the author of four coffee-table books about wild places, and the deputy marsh warden of the Celery Farm Natural Area in Allendale, N.J.

Last Saturday: Photo sequence of the first hatch.

Last Friday: Make way for nestlings.

Earlier Last Week:  All about hatching the eggs.

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