Growing Up Eagle
If Benjamin Franklin had gotten his way, the national emblem of the United States might have been the wild turkey. Franklin thought the bald eagle “a bird of bad moral character” who “does not get his living honestly.” He based that opinion on the fact that eagles will often steal fish from ospreys and other birds rather than catch their own.
Last week, we followed the nesting bald eagles from site selection to nest building to hatching and brooding the eggs and chicks. Regardless of the morality of the method by which the parents acquire meals, the hatchlings grow quickly. By three months, they are ready to leave the relative safety of the nest.
Most fledglings leave the nest at around 11 weeks of age. Sometimes initial attempts at flight are unsuccessful, and the youngsters may end up on the ground. If uninjured, the juveniles can be left on the ground and the parents will continue to provide food to them until they are able to fly. Attempts to replace the grounded pre-fledgling back into the nest can frighten the sibling, resulting with both youngsters on the ground. Once fledged, the young will often fly back to the nest for supplemental feeding by the parents for an additional six weeks or more until their foraging skills are more adept.
Although the babies grow quickly, bald eagles are large birds and take a long time to reach maturity. The characteristic plumage—white head and tail, with dark feathers on the rest of the body—does not show up until the bird is more than five years old. During the first four years of their lives, the immature eagles participate in an avian Rumspringa, exploring vast territories and traveling up to hundreds of miles a day. During the fifth year they will select a breeding territory and settle down. Florida adult resident bald eagles usually do not migrate, but spend their lives within a ten mile radius of their nesting site(s).
Some notable differences in appearance during the first five years of their lives helps to determine a sub-adult eagle’s age:
Age (yrs) Head Body/Wings Tail Bill Eyes_________
1 dark brown dark brown dark brown dark grey dark brown
2 brown mottled with white mottled little yellow light brown
3 whitish chin mottled mottled grey on paler withand neck tip only eye stripe
4 mostly white mostly dark more white dull yellow pale yellow
5 white dark brown white bright yellow pale yellow, almost white
Ideally these birds should be left alone, but our fascination with them unwittingly results in human-bird encounters that often end up causing harm to the bird. Hordes of people flock around a nesting site to watch and photograph each stage of the birds’ progress. Every attempt should be made to observe from an undetected distance, make no loud noises, and use no flash photography or artificial light.
Florida is second only to Alaska in the number of resident bald eagles within the state. Eagles are opportunistic foragers and will scavenge carrion whenever available. One of the best places to see them is around a landfill, especially at dawn or dusk.
Bald eagles live quite a long time. A bird from New York was 38 at the time of its death in 2015. PRWC’s resident bald eagles, Arthur and Bilfred, are not quite that old, but they are getting up there in the years. You can see them every day from 11a.m. to 4p.m., even on holidays like Thanksgiving.
I wonder if Ben Franklin had prevailed if we would be carving the holiday eagle at dinner time today? Best not to contemplate that. Enjoy the yams, squash, potatoes, and green bean casserole—I know I will!
by- Robin Jenkins, DVM