Gulls reflect changes in Great Lake
CBC News Online
Published May 6, 2004
TORONTO - By studying gulls around the Great Lakes, scientists
are tracking changes in contaminant levels in wildlife.
For 30 years, the Canadian Wildlife Service has studied
gulls, hardy, raucous birds that have been exposed to
They've found contaminants in gull eggs have fallen by
up to 95 per cent over three decades.
"I've noticed that the population of birds are larger
than they used to be and noticed not as many eggs broken
because of thin egg shells," said Chip Wesleoh, a
wildlife biologist with the service.
He said the birds are also more successful at reproducing,
but some male gulls have female egg protein in their bloodstream.
The feminization of males existed 30 years ago, but scientists
don't know to what extent.
"Gulls feed on fish and we feed on fish and if gulls
have PCBs and DDT then we probably have them inside of
us," said Wesleoh. The birds are a good starting
point to look for any physiological problems.
The researchers have recently discovered a new pollutant,
brominated diphenyl ether, or BDE, in eggs. The chemical
is used as a flame retardant and resembles a thyroid hormone.