Chance meeting

As part of our privy expedition of the other day we came upon this structure. Convinced, from the vantage of the trail, that it was an out-house I got off the bike to photograph it. Now I am not so sure. If it is a privy it’s at least a two-seater. Even if it is only a storage shed it certainly showed some nice color and texture. I first cropped the image so that it showed only the details of the weathered door to the left, then I thought that the textures set against those of the trees and distant hills gave the overall composition more interest. Desaturating the background served to set the structure apart from the rest of the scene. We had a nice time on the bike and rode the out-n-back from Ross Run to Rattlesnake Rock. On both the outbound and inbound legs we were treated to a view of a solitary Bald Eagle. I know, from discussions with friends, that this magnificent bird can be quite common in other parts of the country. In Pennsylvania, however, glimpses of our national symbol are quite rare indeed.

Ted3

Did you know that by 1963 it was estimated that only 487 nesting pairs of this iconic bird were known to exist in the 48 contiguous states? Did you also know that it was the pesticide DDT which nearly drove this bird to the brink of extinction? DDT was first produced in 1872 and was used with great success to control both Malaria and Typhus during WWII. It wasn’t until the publication of Rachel Carson’s book Silent Spring that the public became aware of the potential for DDT to act as an environmental toxin. DDT is dangerous because it cannot be metabolized and is therefore subject to a phenomenon we call bioaccumulation. You may remember that organisms within ecosystem may be classified as either primary producers (the plants), primary consumers (herbivores), secondary consumers (carnivorous organisms which consume the herbivores), tertiary consumers, or top carnivores. Even if DDT exists in very small quantities it will be taken up by plants. Because primary consumers ingest large amounts of plant material they will take in lots of DDT which cannot be broken down – and it accumulates in their tissues. Because secondary consumers ingest large numbers of primary consumers they consequently take in lots of DDT which cannot be broken down – and it accumulates in even higher concentrations in their tissues. And so on. By the time we get to the top of the trophic pyramid the amount of DDT may be many thousands of times more plentiful in the tissues of a top carnivore than it is in the tissues of the plants at the bottom of the trophic pyramid. It turns out that in such high concentrations DDT influenced the calcium metabolism of many birds of prey such that they produced thin-shelled eggs which failed when set upon. Thanks to some terrific scientific sleuthing this became widely known and DDT was banned in the states in 1972. Birds of prey are now mostly recovered from this insult. Will we ever learn? No, I do not think so.

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