Riding my bike along the Little Juniata River on a beautiful spring evening earlier this week, I was grateful to have the time to be out and about. Though the bleak, leafless trees of early spring were not nearly as beautiful as their green foliage of summer, I was enjoying the scenery along the river, still swollen by the spring runoff.
A large bird flew overtook me from behind, crossed the river and landed in the trees on the opposite side of the river. I could tell from its general shape and size it was some sort of raptor. Moving along at a brisk pace, I didn't want to interrupt my ride. Suddenly, it occurred to me that the bird might be worth a second look and I turned around for a better look. I approached as slowly and quietly as I could and soon realized it was a bald eagle. It flew off before I could snap a picture, but it made my day just the same. I had not been that close to a bald eagle in quite a few years and it got me thinking about how endangered the bird was earlier in my life.
My stream of consciousness meanders in unpredictable directions at times and this chance meeting between a bicyclist and a bird got me thinking about several related topics. We are fortunate today we can find the American Bald Eagle anyplace beyond its image on our money. The population of the iconic bird plummeted in the middle of the twentieth century, thanks to several pressures put on the species.
Chief among the problems was the effect of chlorinated pesticides like DDT, Chlordane, Kepone and several other related insecticides. Beyond a host of other problems, this family of bug killers interferes with the metabolism of calcium. In animals that lay eggs, this causes the thinning of the eggshells. Particularly with eagles and hawks, the weight of the brooding parents often cracked the eggs long before the young birds were fully developed.
To add insult to injury, the young eaglets that did survive often died of pesticide poisoning. Though the levels of pesticides rarely killed an adult bird, the smaller birds were susceptible. Nature author Rachel Carson wrote about this poisoning in her classic Silent Spring 55 years ago but she was ridiculed by the pesticide industry and other adversaries for being an alarmist, hysterical woman. Ten years passed until DDT was ruled illegal for use in the US. Many related chemicals were not outlawed until 1988.
DDT and its related chemical cousins became a problem because they are persistent, bioaccumulative and toxic (PBT). In simpler English, it means they breakdown very slowly and accumulate in fat tissue (since the chemical are derived from petrochemicals and are fat soluble). The very things that made them effective bug killers made them a much bigger problem to human health, as well as birds of prey. The eagle and DDT stories reminded me of the value of well-researched, scientifically-based environmental regulations. Our majestic national bird still flies through the skies of Blair County, and much of the rest of the nation, because of them.