It’s in your nature: Rebounding after DDT ban

DDT (dichloro-diphenyl-trichloroethane) was discovered as a pesticide chemical in 1939. Its widespread use began in the mid-1940s in the U.S. and other countries. Probably the chief reason its use exploded was because it was such an effective contact poison, and in particular, on mosquitoes.

With our involvement in mosquito-infested areas during World War II, this was a crucial weapon to combat malaria and typhus. DDT limited soldiers from contracting these diseases. I even watched a photo clip of DDT being “dusted/dumped” on prisoners to control body lice. The swiss researcher who identified DDT’s potential as an insecticide received a Nobel Peace Prize in 1948.

Beginning in the late ’50s, biologists and environmentalists starting noticing a disturbing pattern. Brown pelican, bald eagle, osprey and peregrine falcon numbers were dropping. Rachel Carsen’s book “Silent Spring,” released in 1962, seemed to be the catalyst for countries to begin research.

Carsen’s book pinpointed the tremendous dumping of pesticides on the planet without thoroughly understanding the side effects. By 1972, DDT use was banned in the United States. It took years for other countries to follow suit, but by 2001 the Stockholm Agreement basically stopped DDT use.

Today only in malaria/typhus regions in Asia, Africa and South America is its limited use occurring.

In my lifetime I have witnessed the increase in sightings and nesting success of the birds mentioned earlier. Bald eagle nests numbered over 300 in Pennsylvania last year, up from three nests in 1983. I am aware of four nests alone in Carbon County.

DDT accumulates in the fatty tissue of organisms. When fish, for example, that contain DDT are eaten by larger fish, the larger fish keep accumulating more and more DDT. When those bigger fish are eaten by higher-order predators, large amounts of DDT now accumulate in them.

Researchers found that DDT was thinning the eggshells of the birds of prey. The eggs were either infertile, or in most cases, broke too easily, ruining any chances for the populations to increase. DDT levels were found higher in humans, and it was surmised that soon reproduction problems would be happening with us, too.

The bald eagle isn’t the only success story. I began camping at Assateague Island, Maryland, in 1982, and for many years I never observed brown pelicans. Now, I can daily see flocks of 15 or 20 birds. With a cleaner environment, even New Jersey Coast vacationers see them regularly. Ospreys which feed almost entirely on fish, as do pelicans, have shown population increases, too.

It is important historically that we learn our lessons and that we carefully research new pesticides and herbicides to check for their short-term and long-term effects on our habitats and organisms.

Remember, wild organisms can give us warning signs before we are harmed. Also, this planet’s animals fill niches that if left open by extinctions, can lead to untold problems for us as well.

Test Your Outdoor Knowledge:

What uncommon owl is most similar in size and color patterns as the great horned owl? A. long-eared owl, B. short-eared owl, C. barred owl, D. saw-whet owl.

Last week’s trivia answer: Since 1980, wood thrush populations have dropped more than 60 percent. Hopefully we can find ways to increase their population so we can keep hearing their morning flutelike calls.

Contact Barry Reed at breed71@gmail.com.