Our young eaglets are growing fast and now look like real eagles. "Big" (as many of you like to call the largest bird), was hatched on April 10 making him or her 11 weeks old, and "Little" is about 4 days younger. Both eaglets are approaching the size and weight of their parents. In fact, young bald eagles have longer wing and tail feathers than their parents (biologists don't know why).
As astute viewers have observed, the adult eagles are rarely seen now except to make a quick prey delivery to the nest. They don't bother to tear the food apart, but allow the eaglets to carve up their food with their sharp beaks. Usually, the adults are within site of the nest (or perched out of view of the camera high in the nest tree). Adults on the coast of Maine have feeding territories up to a mile or two away from the nest depending on the location of feeding areas and competition from nearby nesting pairs.
About two weeks ago our eaglets started "limbing out," that is leaving the nest and perching on adjacent limbs. They don't go far from the nest and remain in camera view. Don't be surprised to see them start to fly/hop from limb to limb or nest to limb. Watch for the eaglets to grasp hold of a limb or the nest and beat their wings vigorously. This behavior accomplishes two things - first, its strenghtens their wing muscles in preparation for their first flight, and second, its gives the birds a good sense of the size and power of their wings. It takes considerable agility for bald eagles to fly in and out of trees with a 7 foot wingspan, and these pre-flight routines help them guage their own size. On breezy days, watch for the eagles to extend their wings and float briefly into the wind before settling down on the branch again. Sometimes they will snatch a branch from the nest and float into the air with the limb in their talons. A large portion of the day is spent preening (adjusting and oiling) their new feathers.
"Big" could make his or her maiden flight any day now. I studied the "fledging" phase of bald eagle ecology years ago as part of my doctoral research at the University of Maine. Young bald eagles make their first flight at 11 to 13 weeks of age. What makes a young eagle decide to leave the nest? After watching about 20 eagles fledge, I can't say for certain. I never saw the adults encourage the young to fly or to entice them away with a food item. Just like kids, I believe they just know when its time to try out their new wings!
On many occasions I witnessed the first, awkward flights of a young eagle. I recall that many times this occurred during one of their floating-into-the-breeze experiments when they missed the branch or got blown by a gust of wind. Suddenly, they realize they are airborn with nothing but a great void underneath them! The young eagles don't know the art of soaring and thermals, so they begin flapping vigorously. Since eagle nests (like this one) are located near water, the first flight is along the shoreline over a lake, ocean, or river. Usually, the first flight is no more than 200 to 500 yards. The shoreline environment provides many opportunities for landing - a log or rock on the shore, low trees, or maybe a large white pine. I've seen young eagles land in the water and row to shore with their wings. More often, they try to land in a tree. On several occasions I watched young eagles land on branches only to have their momentum carry them forward so they end up hanging upside down with wings extended like a giant bat. On other occasions I've seen them tumble from branch to branch in a tree until they desperately grasp a perch or talon full of twigs to stop their fall.
Adult eagles don't seem overly concerned that their young have fledged. "Big" will squawk and squeel at its parents when it gets hungry or if it sees the adult returning to the nest to feed "Little." A week or two after fledging, the adults will start to deliver food to the fledged eaglets in nearby trees. Although it is difficult for eaglets to learn how to grasp a fish with one foot and hang on to the tree with another. I've seen many a disappointed fledger hang their head in discouragement after fumbling and dropping a fish just delivered by its parents.
Fledging is a dangerous time for young eagles. They can get injured during their first flights. Sometimes, boaters will encounter an injured eaglet and bring it to us for rehabilitation. They are also vulnerable to predators. Young eagles who land on the ground will "climb" a tree by evening by hopping upward branch by branch. This gets them out of the way of ground predators like raccoons and foxes.
Don't be surprised to visit the webcam in the next week and only see a single eagle in the nest. "Big" could go any day. Once eaglets leave the nest, they usually develop the flying skills (or hunger) to make the flight back to the nest within a few days. The nest will remain a center of activity for the eagle family through the summer and serve as an easy landing spot for future feeding.
Mark McCollough, U. S. Fish and Wildlife Service