An Eye for Eagles

Its soaring flight, with its pure white head and tail glistening in the sunlight, is really inspiring; and it adds grandeur to the scene as it sits in a dignified pose on some dead tree, its white head clearly visible against the dark green of the forest background.

~Arthur Cleveland Bent, 1937

Interestingly, the famed ornithologist quoted above also had this to say abut our national bird…“On June 20, 1782, our forefathers adopted as our national emblem the bald eagle, or the “American eagle” as it was called, a fine looking bird, but one hardly worthy of the distinction. Its carrion-feeding habits, its timid and cowardly behavior, and its predatory attacks on the smaller and weaker osprey hardly inspire respect and certainly do not exemplify the best in American character.” He also was not in favor of Benjamin Franklin’s preference for the Wild Turkey as our national symbol saying “such a vain and pompous fowl would have been a worse choice.” A Golden Eagle would have satisfied him, being a “far nobler bird”, but, as it is not strictly American, it would not qualify. So, in spite of its perceived character failings, Bent conceded that the Bald Eagle is at least a majestic looking bird. I agree, majestic, indeed. And, in spite of the scarcity of waterfowl on my recent circuit through the wildlife refuges of nearby states, I was greeted at every one of them by at least one Bald Eagle,  Haliaeetus leucocephalus.

Eagle nest location

Site of eagle nest along the Wildlife Loop at Chicncoteague NWR (click photos to enlarge)

The best views were at Chincoteague National Wildlife Refuge in Virginia. On my last trip there, two years ago, I saw eagles near their nest site in a small grove of trees adjacent to the Wildlife Loop on the refuge.

Bald Eagle nest

Pair of Bald Eagles sitting on nest

The nest is apparently still being used. Two adult birds were sitting in it, barely visible if you didn’t know where to look. The huge stick nest sits in a large pine less than 100 yards from a popular trail and is easily visible by the thousands of visitors that walk, cycle, and drive (cars are allowed on the loop after 3 p.m.) the loop each year. The refuge also has an eagle cam in their visitor center which provides lots of information and updates on the status of the nest. I believe this nest has been in use since 2012, when the previous one fell during the winds of Hurricane Sandy. Eagle nests tend to be used year after year, with more material added each year. This can lead to huge nests over time. A typical Bald Eagle nest is 4 to 5 feet in diameter and 2 to 4 feet deep. The largest Bald Eagle nest on record, located in St. Petersburg, Florida, was 9.5 feet in diameter, 20 feet deep and weighed almost 3 tons. That nest holds the record as the largest nest in the world built by a single pair of birds.

Bald Eagle on snag

An adult Bald Eagle poses nicely on a dead snag near its nest

On my second morning at Chincoteague, I was rewarded with one of the eagles perched out in the open near the nest. It was a classic perch, a tall, lone dead pine, a perfect place to survey your world if you are an eagle. I set up my tripod, put on the 500mm with a 1.4 teleconverter, and shot way too many shots as the eagle watched the comings and goings of ducks, ibis, and various other birds.

Bald Eagle stretch

The eagle stretched as if to fly (these images cropped compared to previous one)

At one point, the eagle leaned forward and stretched out. I thought it might launch itself into the air, a shot I would love to capture.

Bald Eagle scratching

Bald Eagle scratching

But, it was merely to get at an itch. The eagle leaned back and brought up its formidable talons to delicately scratch its face.

Bald Eagle scratching 1

Impressive talons stretched out to scratch

The talons can be used for a delicate operation like preening feathers, or for killing the eagle’s prey. According to the web site of the National Eagle Center, the crushing strength of each talon is estimated to be at least 400 pounds per square inch (psi). That is at least ten times stronger than the average grip strength of between 20 to 40 psi for a human hand. The talons on a female eagle are longer than those on a male (females are larger in general). The hind toe (hallux) has the longest talon and may be almost two inches long on a large female.

Bald Eagle on snag 1

Regaining the royal pose after a scratch

Another notable feature of a perched Bald Eagle is its impressive beak. Like the talons, the beak is made of keratin (similar to our fingernails). And its hooked tip and large size relative to the head size is an identifying feature for eagles even in poor light or at great distances (relative to vultures and some other large birds that people might confuse with eagles).

Bald Eagle head

Bald Eagle head (heavily cropped image)

Of course, the eyes of an eagle are one of its most impressive features. They are almost the same size (weight) as a human eye, even though an adult eagle might weigh only 14 pounds. Obviously, an eagle’s eyes take up a large proportion of its skull compared to ours. No one knows exactly how much better an eagle can see than us, but there have been some comparisons. Rod and cone cells on the retina send sight information to the brain. A human eye has about 200,000 cones per millimeter in a concentrated area on the retina. A Bald Eagle has a much higher concentration of about one million cones per millimeter. An online search showed a range of estimate that an eagle has anywhere from 4 to 8 times the visual acuity of a person.

Bald Eagle at Mattamuskeet

Last Bald Eagle of my refuge trip (at Mattamuskeet NWR)

I probably observed over twenty Bald Eagles on this trip, stopping to enjoy each sighting. I guess I must respectfully disagree with Mr. Bent in his assessment of our national bird. It is always a thrill to see one, and my recent tour of refuges showed that eagles are doing well here in the East. In fact, Bald Eagle populations nationwide have recovered enough that they were officially removed from the endangered species list in 2007. Back in 1963, the all-time low population of Bald Eagles in the lower 48 of the United States was estimated at 487 nesting pairs. When they were delisted, eagle populations had soared to an estimated 9789 nesting pairs in the lower 48. One recent estimate put the total population (not just nesting pairs) of eagles in North America (including Alaska and Canada) at 69,000. They are now being celebrated in many areas with eagle festivals, eagle-watching tours, and eagle nest cams. For me, the delight comes from seeing one perched in a tree, looking out over the terrain, searching for prey, and then lifting off with powerful wing beats into a blue sky. I, for one, am glad they are back.

8 thoughts on “An Eye for Eagles

  1. I, for two, am glad they are back. I’d love to go out with you sometime “eagle hunting”. I’ve never seen them except from afar.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s