Sunday, February 3, 2008

The Bald Eagle - A Tumultuous Journey

Photograph by David Powell

“For my own part, I wish the Bald Eagle had not been chosen the representative of our Country. He is a bird of bad moral character. He does not get his living honestly. You may have seen him perched on some dead tree near the river, where, too lazy to fish for himself, he watches the labour of the fishing hawk; and when that diligent bird has at length take a fish, and is bearing it to his nest for the support of his mate and young ones, the Bald Eagle pursues him and takes it from him.”

“With all this injustice, he is never in good case but like those among men who live by sharping and robbing he is generally poor and often very lousy. Besides, he is a rank coward: The little King Bird, not bigger than a sparrow, attacks him boldly and drives him out of the district. He is by no means a proper emblem for the brave and honest Cincinnati of America who have driven all the King Birds from our Country . . .”

“I am on this account not displeased that the figure is not known as a Bald Eagle, but looks more like a Turkey. For the truth, the Turkey is in comparison a much more respectable bird, and withal a true original Native of America . . . He is besides, though a little silly and vain, a bird of courage, and would not hesitate to attack a grenadier of the British Guards who should presume to invade his farm yard with a red coat on.”

Benjamin Franklin
January 26, 1784

So began the rocky road of the National Bird of the United States, the majestic Bald Eagle. Unappreciated and feared, all raptors were viewed as varmints by the general populace, even after the Migratory Bird Treaty Act was passed in 1918, and the 1940 passage of the Bald and Golden Eagle Protection Act. Humans have been the most significant cause of mortality for the Bald Eagle and other raptors, and it has only been in the past 35 years that their persecution has declined. Early settlers shot and trapped Bald Eagles because of their perceived threat to livestock, competition for game, or tradition such as the use of feathers by Native Americans. This practice continued; however, even after the above laws were in place. Shooting, trapping, and intentional or accidental poisonings were responsible for 38% of the mortality of Bald Eagles recovered from 1963 to 1984 (Wood et al. 1990). Over 128,000 bounties were paid in Alaska from 1917 to 1952 because Bald Eagles were thought to impact salmon fishing. Significant numbers of Bald, and especially Golden Eagles, were shot by ranchers in western states earlier in the 20th century because of suspected livestock depredations. One such incident, which occurred in Wyoming, involved the shooting of >770 Bald Eagles for which the shooters were paid $25 per dead eagle.

The eagles were further persecuted by those that collected their eggs, a common practice up until 1940. Bald Eagles also suffered from reduced reproductive success due to eggshell thinning related to DDT poisoning. Population declines of eagles, Osprey, and Peregrine Falcons particularly in the eastern US lead to the ban of this pesticide in 1972, but not before the Bald Eagle (1966 and 1978) ) and Peregrine Falcon were listed under the Endangered Species Act of 1973. Since then; however, population trends have increased for the three species most affected by this chemical. In the early 1980s the nationwide population of Bald Eagles was estimated to be 70-80 thousand birds, and that number had grown to 100,000 by 1999.

This recovery represents on of our nation’s most successful conservation stories. By the late 1990s, Bald Eagles were successfully nesting in all but 2 of the contiguous United States. Interestingly, although most citizens now revere our national symbol, today lead poisoning is considered a significant cause of mortality, and has been reported in 34 states. The source of the lead is the pellets and bullets in hunter- shot waterfowl, deer, and other game species. Other factors continue to affect populations such as collisions with vehicle, electrocution on utility structures, and an unknown number that are killed annually for their feathers which are sold on the illegal feather market.

The adults are easily distinguished by the characteristic white heads and tails, and bright yellow bills and feet. The youngsters; which are very similar in appearance to their cousin, the Golden Eagle, often defy identification. Beginning life as a mostly dark brown bird with a black bill, they undergo a variety of plumage changes before they acquire the adult plumage at age 4, when they are sexually mature. The record longevity in the wild is 28 years, with a captive Bald Eagle surviving until age 36. It is likely that, similar to other raptors, mortality is high the first year, with increasing survival to adulthood.

In New Mexico, we generally see the Bald Eagle only during the winter months, where they are primarily feeding on waterfowl, particularly wintering ducks. The numbers of eagles present here during the winter is largely affected by the weather up north. If those lakes are frozen, forcing ducks and other waterfowl further south, likewise the eagles follow their food source. By the time you read this, most of our birds will be heading north for nesting areas located near large bodies of water. Fewer than 8 pairs of Bald Eagles nest in New Mexico, mostly in the northernmost counties, but during the winter months they might be observed just about anywhere, even far from the nearest river or lake. I’ve seen them calmly roosting in canyon country far from any water source, not surprising for a bird that can go 5-7 days between meals.

Speaking of meals, this article would probably have been much different had Benjamin Franklin has his way with our fledgling country. Thanksgiving might have been celebrated in a very different style!

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