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Big birds causing flap on Leslie Spit

	Nest of double-crested cormorants at the Leslie St. spit

Apr 04, 2008

Dale Anne Freed
Staff Reporter

Conservation authority concerned acidic feces killing trees, but birds' defenders argue they deserve to be protected

The double-crested cormorant has made its annual pilgrimage back to Tommy Thompson Park from the Gulf of Mexico.

The problem is, their poop is killing the trees.

"We have a concern about the loss of tree cover at the park where they nest. Their feces are acidic. It's changing the soil conditions and killing the trees," said Gord MacPherson, manager of restoration and environmental monitoring projects for the Toronto and Region Conservation Authority.

The conservation authority organized a public meeting last night at an east-end church that drew some 60 people, including birdwatchers, sailing club members and academics.

So, what to do about the large black birds, some 12,500 adults and about the same number of young?

According to Chip Weseloh, wildlife biologist with the Canadian Wildlife Service, the voracious eaters swallow about a half-kilogram of fish a day, about 1,700 tonnes of fish per season, mid-April to October.

Potential strategies to control the bird population range from doing nothing to harassing them to egg-oiling – applying a non-toxic food grade oil to their eggs within eight to 10 days of laying to prevent embryo development.

Glenn Coady, of the Toronto Ornithological Club, said he loves them.

"We've got the largest double-crested cormorant population on the Great Lakes. For sure, we have an obligation to protect them," he said.

"With regards to the fish they eat, they're rectifying a problem. They eat fish like alewife and round gobies that were introduced in bilge water from foreign ships."

Each bird excretes about a third of a pound of waste per day.

Although the birds have been responsible for deforestation, Coady made his priorities clear: "I don't value trees more than birds."

He said they nest in cottonwood trees.

AnnaMaria Valastro, of the Peaceful Parks Coalition, said she is shocked by proposals to control the birds.

"These birds are refugees. They're being shot in New York State," she said.

"Toronto and Region Conservation should advocate to protect these birds."

Rob Laidlaw, of the group Cormorant Defenders International, said it's not necessary to oil the eggs.

"Let's encourage the cyclists to come, which would keep the birds from nesting," he said.

The birds have been increasing in numbers by about 20 per cent a year since 1990 after the use of the toxin DDT was banned in North America, said Ralph Toninger, senior project manager for the conservation authority.

"Our goal is to achieve a balance between a healthy, thriving cormorant colony and other park values and uses," he said.

"We have a concern if there will be enough forest canopy because we have little enough forest canopy to start with."

In a letter to Mayor David Miller, Valastro wrote: "We are asking that your office protect the waterbird colony at the Leslie Street Spit, and allow it to evolve naturally without human intervention.

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