Thursday, May 19, 2011

Eagle camara in Decorah, Iowa

One of our young eagles, August, 2010
     By now probably most of you know of the Eagle camera focused on an eagle's nest in Decorah, Iowa. It can be addicting to watch these eaglets in the nest, and just sit there waiting for one of the parents to bring breakfast, lunch or dinner. What most people don't realize is that it is very unusual for a pair of eagles to successfully raise 3 eaglets in a single year. Often 2 or 3 eggs are laid, but frequently one or two of the eaglets do not survive. This is either because there is not enough food to raise 2 or 3 such large birds or there are other environmental challenges such as cold, ice, wind. Also sibling eaglets are much like human siblings. There is competition and disagreement, but in the case of the eaglets, this disagreement can be a life and death issue. Frequently, a stronger nestling will push a weaker one away from the food source and may even push the weaker one out of the nest. I watched these Decorah eaglets for quite a while, and they seem to get along fairly well. This speaks to the abundance of food available for the parents at this site. Though I do think one of the three are significantly smaller and less developed than the other two. This might be because of receiving less food, or it might also have been the third to hatch. The last to hatch and especially if that hatching was delayed a day or two would be behind and would always get less food than the other two. The parents do not make any attempt to keep track of who eats and who doesn't. They put the food into any open mouth that is around. So if one eaglet is too weak to get close enough to demand food, it would be at a significant disadvantage.
     We are lucky enough to live on Lake Michigan about 1000 feet from an eagle nest tree. We can't see the nest but we see the eagles often. Last year  in their 4th year here they raised two eaglets which we thought was quite a remarkable fete. It was fun to see these two young eagles learn to soar and compete with each other riding the updrafts. Prior to that they had raised a single eaglet for 3 years in a row.
     Another indication that our adult eagle pair is pretty well off here on Lake Michigan is the fact that they allowed the yearling bird from 2 years ago to remain in the area even into the early nesting season last year. They did not allow that immature eagle to get near the nest but neither did they chase it out of the area. The latter would be more normal behavior. Again I think this means that there are lots of fish for the taking in that lake and probably plenty of varmits which fill in the gaps in the food cycle.
     Another interesting fact about eagles is their weak cry. From such a large bird, one would expect quite a cry but they have a very typical raptor's cry. The red tailed hawk has a similar cry. If you watch the Decorah video for a while, you can sometimes hear the parents approaching the nest with their relatively soft high pitched call. However, the parents do vocalize softly to their young during their caretaking duties.
     If by some chance you have not become addicted yet to watching our national bird in its most private duties, here is the website for the Decorah camera. Also there are several recordings from portions of this year's upbringing from the laying of the eggs, to the pipping, the hatching, and then the young eaglets in all their fuzzy glory.

  Below is a link to nest in New Jersey. I haven't looked at this camera before but it also appears that this nest has two eaglets.

     I notice that yesterday, a fairly cold spring day with rain, the female (probably) is brooding the young ones, at least 1 1/2 of them. One eagle is completely and the other is partially covered by her body. But the fact that she is there at all indicates her instinctual  knowledge that these youngsters need protection from the cold and rain. On other sunny days, these three are old enough that both parents will often be gone from the nest at the same time searching for food. When the eaglets are younger, the parents never leave them alone in the nest. They take turns brooding and guarding the eaglets. I find these instinctual behaviors very fascinating. I guess that is why I am in the ranks of birdwatchers.

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