Naturespeak A naturalist's view of the world

February 28, 2011

On Eagle’s Wings

Filed under: Uncategorized — wykes @ 2:07 pm

Although it may not sound like a great place to be, the mountainous landfill close to the Lake Erie shore in N.E. Monroe County (MI) is a spectacular place to watch winter raptors.  The birds gather there to take advantage of the updrafts racing over the grassy slopes and to hunt the mice living on those grassy slopes. I feel fortunate that this place is along my route to the park, so I can eyeball it at sunrise and sunset.  On one late afternoon pass – even considering the troublesome reality that I also had to keep my eye on the road at the time– I spotted a Kestrel, a Northern Harrier, a Rough-legged Hawk (I’ve shown you this bird in an earlier Naturespeak), and a Red-tailed Hawk.

Last week two Bald Eagles caught my eye at this location. Bald Eagles always catch my eye, but these two birds were cavorting so actively that I was forced to pull over and watch them.  I use the word “force” because they indeed exerted some mysterious energy which caused my hands to turn the steering wheel toward the road shoulder. These massive birds don’t normally engage in mousing like their smaller cousins, so it appeared that these two were simply enjoying the wind under their wings. Note that I said “appeared” because I would be the last to insert human emotions into the activities of a child of nature. But, these birds were not accomplishing anything except wind surfing. They were gliding up and down, over and back, and even sparring with each other (see above) like two kids on an ice pond. Now, I did intend to use the term “kids” here. Let me explain.

That these eagles were both “kid” birds was obvious by their dark appearance.  Since bald eagles don’t get their bald – or white – heads until after their 4th year, they exhibit a variety of patterns as they mature over their first quadrant of years. One can usually tell how old a particular pre-adult bird is by visually checking off the field marks. Let me point out that my use of the word “immaturity” has nothing to do with behavior or size. Immature eagles are full-sized as soon as they leave the nest and they rarely engage in hissy fits or tantrums. Let me also point out that I will stop using parentheses now that I have achieved this, the “meat”, of the blog.  Oops, sorry about that.

Although it is a non-scientific exercise, it has been calculated that eagle years are equivalent to about 2.5 human years. By that standard, the two birds I am discussing here were between 3 & 5 years of age. Since I don’t know of any 5 year human child that can fly, I’ll drop this line of discussion and re-direct it to the fact that one of the birds was in its 1st year and the other in it’s 2nd.  In other words, even though they were “hangi.., darn it,… hanging out together they were not nest-mates.  How do I know, you ask?

O.K., here goes. The one year old bird (see above) is pretty dark overall. There is plenty of white sprinkling on his underwings and wing pits, but very little on his chest and belly.  These portions are evenly brown. The belly is a lighter shade of brown than the chest, as a matter of fact. You’ll also note that his tail is whitish with a dark band at the edge and his bill is relatively dark. I wasn’t able to capture this angle, but you’d also see that there is was no white patch on the bird’s back. Most significantly, I want you to look at the trailing edge of the wing and note that the feather edging was even.

Now, take a good look at the second bird. In the beginning photo, it’s the one at the upper right. Note that the edge of this bird’s wing appears ragged. This is a 2 year old bird. At least half of the secondary feathers are molting and replacing the baby feathers (I would have normally used parentheses there but a promise is a promise) which leads to that uneven appearance (see below and here). This single trait is enough to peg a 2 year old eagle anytime, but you should also look to see that there was quite a bit of white speckling on the belly, lighter feathering on the head, and dirt on the feet which indicates that it was able to walk. That last fact was untrue, by the way, but the rest was the honest truth.

Now, just for kicks, take a look at this last shot (below) and see if you can tell which bird is which?  I don’t think you’ll need me to provide the answer. (Especially if you were mature and paid attention).

1 Comment »

  1. Thank you for sharing all that knowledge! I love raptors and I would have been forced to the side of the road to watch them as well. How wonderful that you were able to get all these photos of them. I’ve been forced to the side of the road to watch any kind of wildlife. I learned a lot from this post.

    Comment by Genny — February 28, 2011 @ 5:28 pm

RSS feed for comments on this post. TrackBack URL

Leave a comment

Powered by WordPress