Friday, July 3, 2015

Making a Big Splash

Osprey use at least three different methods for spotting prey: identifying a fish while seated on a branch overlooking water, soaring in circles over open water, or by hovering above a single location such as this bird is doing in the photograph. It is the most energy intensive method requiring balancing the entire body to stay stationary. That is why the legs have been lowered. Hovering also often means they have actually spotted a fish, but they are waiting for just the right moment to strike.

I included another photo from this series a few posts ago where a Kingbird was harassing an Osprey that was trying to concentrate on fishing. In this image, the Osprey actually looks vexed and, yes, that is a railroad track in the background.

I suppose birds that have the ability to dive underwater have to be aware of how deep the water is so that they do not break their neck. I have watched Kingfishers that I suspected were aware of how deep they could dive without hitting bottom. In any event, Osprey also have a couple different techniques for capturing a fish, one of which is the snatch. Notice the small fish in midair behind the Osprey. It may have been the target.

This photo communicates some of the energy expended in catching a fish. Notice, again, the small fish just reentering the water right behind the Osprey. The water probably is not too much deeper than where the Osprey's feet are in this picture.

Imagine if you will, a fisherman on the edge of the pond trying to catch a fish. He looks around and sees three more people fishing scattered around the pond. If he does not catch a fish, he will not eat today. The same is true for the others. This goes on day after day and, in truth, there are many more than three other fishermen. How many fish does the pond have to hold to meet the requirements of all those hungry mouths? That is one of the surprises of the pond — that it would hold enough fish to keep so many birds fed. Another surprise is that there are any fish in the pond that could reach the size of this one. The Osprey was actually having trouble dragging it out of the water.

This is not the same fish as the previous photo, but was taken a few days later. You can see it is at least as large as the other one. It makes me wonder how many fish of this size the pond could possibly hold.

Often after an Osprey catches a fish, it circles around carrying the fish and crying out repeatedly with it's one-note song. I use to wonder if they weren't bragging about their catch. It finally dawned on me that a bird cannot go to a tree limb immediately to eat it's catch because the fish would still be able to put up some fight making it possible for the bird to lose the fish in the process. So they have to fly around long enough for the fish to expire or very nearly expire before they land with it. The blood on this fish is due to a talon inadvertently piercing it's gills. I know, I feel sorry for the fish too, but they have to eat.

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