NS Eagle Population Survived DDT Scare, Flourished In Past 50 Years


 It’s the time of year when bald eagles get restless. Many that spent winter on the coastlines and estuaries of Nova Scotia remember their traditional nesting grounds in Cape Breton or even further north to Newfoundland. By the first weeks of March, they will be moving.

 

Bald eagles at the Sheffield Mills Eagle Festival

When I was younger, it was rare to see a summer eagle in Nova Scotia south of Cape Breton. The DDT tragedy of the 1950s extirpated bald eagles from most of the Atlantic seaboard of North America. Cape Breton Island stood as the southernmost refuge.

As the conservation pendulum swung, birds from there repopulated the rest of this province as well as several American states. The scope of the northward migration these past few years is homage to the protection highlands north of the causeway gave this species half a century ago.

For those who don’t remember the DDT crisis, or never heard of it, it came in the aftermath of the Second World War. DDT was a chemical used to spray battle zones infected with malaria and typhus carried by biting insects. After the war, it became the main insecticide for agriculture, winning a Swiss chemist a 1948 Nobel Prize for refining its use.

By the mid-1950s, however, people realized that bald eagles had disappeared from the lower 48 American states and many parts of southern Canada, and species of hawks were also vanishing. When scientists began to close ranks with bird watchers, it was found many songbird species were also declining.



Eggshells of wild birds were getting thinner and many either broke from the parent’s weight or didn’t hatch. DDT in the ecosystem was judged to be the cause. In the case of bald eagles, fish and smaller birds ate insects sprayed with DDT and concentrated the harmful chemicals in their bodies. When eagles ate them, the concentration increased again.

It was American author Rachel Carson’s 1962 book “Silent Spring” that first conveyed this information to the public in a deeply disturbing way. I was a young journalist in first year university when I read it, and I remember “Silent Spring” as one of the few books of my lifetime that thoroughly shocked me.

Carson’s writing is widely credited with starting the world environmental movement, and changes resulted, if slowly. By 1972, the use of DDT had been banned in the USA. It took Canada another 13 years to follow suit.

Things have changed in Nova Scotia since then. After ice-out, there is rarely a day when I don’t see an eagle from my Waverley home. Whatever the cause, the bald eagle has gone from rare to regular in my lifetime.

That’s something I’m grateful for.