Friday, April 17, 2015

The Homemakers

There is a dead branch on a tree overlooking the marsh pond that is a favorite perch of larger birds. At this point in the life cycle of a tree, most of the smaller branches have fallen off, so there is less risk of a bird accidentally damaging it's wings when landing there. A mated pair of Osprey are one of the bird species that enjoy the view.

If you watch a bird land on a tree branch, it is actually pretty cool. First of all, they face into the wind so they can take full advantage of the wind in their wings. They also come in below the branch they want to land on. As they near the target, they go into a steep climb calculated to cause a stall just as they reach the branch. It is similar to a person who, before kicking a football, has to judge how many steps he has to take and how far apart they have to be to get to the ball at just the right point. This permits a soft landing and reduces the risk of injury. Osprey, like all raptors, have quite a set of talons as you can see here.


Osprey are obsessive about continually fortifying their nest. I have seen them add branches and nesting materials before nesting season, while the chicks were in the nest (which is a little dicey since they are a bit clumsy with a big stick) and after the chicks have left the nest. The last gives you an indication of their forward thinking. After one of the Osprey flew off in the last photograph, the other took a branch in it's bill and tested it to see if it would be easy to snap off. I have enlarged it a little to make it easier to see.

The trees in this picture are in the same area as the previous photos. I don't know what motivated me to keep my eyes on this Osprey because it wasn't doing anything particularly unusual, but I watched it fly through a tree and snap off a dead branch. How it was able to tell the difference between the dead branch and one on which the buds had simply not emerged (and is therefore green) is beyond me. Consider also that it was flying, so the choice of branch had to be made rather quickly.

And, here it is with the branch it broke off. I don't know about you, but that kind of exhibition of reasoning power in a "dumb" bird impresses me. I saw this same kind of thing one other time on the Patuxent River. Since then, I have read accounts where others have seen the same behavior.

DDT did not only affect the Bald Eagle — although you hear them mentioned almost anytime the subject comes up. Many species were experiencing alarming reductions in numbers until Rachel Carson put her finger on the cause in her book, "Silent Spring."

As populations of many species such as Osprey have again increased, ideal nesting locations have become contested by competing families. These two Osprey are desiring to build a nest on a utility pole only a couple poles from another established nest. I have seen this behavior before. This pair are almost certainly wanting to build their first nest. I watched a pair do the same kind of thing (make poor choices) for five years before experiencing successful. There has been a lot of squabbling between the two pair and it may even be that one of these two birds is an offspring of the pair in the other established nest.

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