The sight of the herring gull colony on Near Island was overwhelming,
even for a seasoned biologist like Mike Gilbertson. This was the
time when the gulls should be busily feeding their squawking, demanding
brood, but what the Canadian Wildlife Service biologist found instead
was a scene of devastation. As he walked through the barren sandy
expanse where the gulls breed and raise their young, he encountered
unhatched eggs and abandoned nests everywhere, and here and there,
In a quick count, Gilbertson estimated that 80 percent of the chicks
had died before they hatched, an extraordinary number. As he examined
the dead chicks, he saw grotesque deformities. Some had adult feathers
instead of down, club feet, missing eyes, twisted bills. Others
looked shriveled and wasted, and they still had the yolk sack attached,
suggesting they hadn't been able to use its energy for development.
about the symptoms seemed vaguely familiar, but Gilbertson knew
he had never seen them in the field. Where had he heard about this
before? The question nagged at him as he completed his melancholy
tour and headed back by boat to his laboratory.
few days later, it suddenly came back to him. Chick edema disease-an
affliction he had read about as a student in England. The same deformities
and wasting had shown up in the offspring of chickens exposed to
dioxin in laboratory experiments. If the dead gulls had all the
symptoms of chick edema disease, he thought, there must be dioxin
contamination in the Great Lakes.
colleagues and superiors greeted this theory with skepticism bordering
on derision. Some doubted his diagnosis perhaps because dioxin had
never been reported in the lake, a doubt that only deepened when
analysis on gull eggs with the methods then available could find
no trace of dioxin.
Gilbertson neverthless remained convinced that Great Lakes birds
were showing signs of dioxin contamination, but he found no support
for pursuing his theory.