Bob Beyfuss: How an insecticide pushed bald eagles to brink of extinction | Life and Leisure


Bald eagles may seem like a stretch for a garden pillar, but read on.

In 1939 the chemist Paul Müller synthesized the chemical insecticide DDT (dichlorodiphenyltrichloroethane). He worked as an independent scientist for Geigy Corporation on ways to protect clothing from insect damage and a safer seed disinfectant. In those days, highly toxic compounds of mercury, arsenic and cyanide were the most common types of insecticides.

Müller was motivated by severe food shortages in Switzerland and by malaria epidemics in Russia and elsewhere that worsened at the start of World War II. Müller’s work on combating insect-borne diseases was awarded the Nobel Prize in Medicine. In the winter of 1943/44, 1.3 million people were treated with DDT to defeat a typhoid epidemic in Naples.

DDT was viewed as a “miracle cure” that would protect the global food supply from insect pests and eradicate insect-borne diseases without harming humans. As the National Academy of Sciences said in the 1970s, “Few chemicals do humans owe as much as DDT. In just over two decades, DDT has prevented 500 million malaria deaths that would otherwise have been inevitable. “

Unfortunately, the widespread use of DDT has had some negative side effects, more specifically one of the compounds it breaks down into, DDE (dichlorodiphenyldichlorethylene). DDE affects the reproductive process of birds of prey by concentrating in the food chain and breaking eggshells before the eagles hatch. DDE in water was absorbed by algae, passed on to algae-eating fish, and then to larger fish, and finally to birds of prey in the food chain. The number of eagles, hawks and other birds in the food chain dropped sharply after their introduction. DDT is also remarkably persistent in the environment, with a half-life of 150 years in aquatic environments.

Bald eagles, our national symbol, were endangered as early as the 1920s, but DDT appeared to be accelerating their decline. In 1972 the newly formed Environmental Protection Agency banned their use in the United States.

Now is the time for a look back from that old columnist. As a child growing up in the 1950s and 1960s, I remember that it was not only acceptable but absolutely necessary for farmers to shoot and kill all birds of prey whenever they were sighted. Eagles, hawks and owls were all considered “chicken killers” and therefore had to be killed, and no one questioned the practice. It is questionable whether the ban on DDT alone saved these birds from extinction, or whether societal attitudes in general helped bring them back.

In any case, bald eagles are critically endangered and we all now have a chance to spot these magnificent birds. I remember the early 1970s waiting in line in Everglades National Park for hours to catch a glimpse of a bald eagle nest. Last summer, I saw bald eagles almost weekly near my home on Catskill Creek in Preston Hollow, as well as near the Hudson River, Schoharie Reservoir, and Ashokan Reservoir. Its success is the result of targeted restoration attempts by the nature conservation departments at the national level as well as the federal protection authorities.

Bald eagles are among the largest bird of prey species in North America. They are easily recognized by their white feathered heads (not bald like vulture heads) and tails with an evenly black body. Their wingspan is often up to 7 feet wide, and their hook-yellow beaks and huge claws make them look even more impressive. They are almost always found near waterways, where they feed on dead and live fish, snakes, turtles, ducks, rabbits, muskrats, and other carrion (dead animals). They pounce on prey and can even carry large animals away in their long claws. The hookbills allow them to tear apart their food easily. If they fly at a speed of 40 miles per hour, they can reach 100 miles per hour when attacked and soar up to 10,000 feet in altitude. You have incredible eyesight. “Eagle Eye” is a legitimate compliment!

Immature bald eagles do not have the distinctive white head and tail feathers that the adults do. It takes four to five years for them to mate after some sophisticated advertising behavior. Once paired, they stay that way until one partner either dies or disappears. Their nests, called eyries, are made of sticks and are constantly enlarged, sometimes more than 7 feet in diameter and more than 2 feet deep. An eagle’s nest can weigh up to a ton!

Anyone reading this column will be within reach of a bald eagle, and I encourage you to look for one. It’s exciting to see them!

Bob Beyfuss lives and works in Schoharie County. Email him at