30,000 cormorants destroying lakeside park

[Spiel]

30,000 cormorants destroying lakeside park

 

 

May 20, 2009

Leslie Scrivener / www.thestar.com

 

 

Cormorants have overtaken a peninsula of Toronto's Leslie Street Spit,

which, thanks to aggressive nest building, is barren but for one tree. (May 13, 2009) MICHAEL STUPARYK/TORONTO STAR

 

 

Dark and swift, flocks of cormorants soar above Lake Ontario before hundreds of them finally dip down to the diamond-flecked water. It's a stirring sight on a bright spring day.

 

But cormorants are less beautiful on land.

 

One arm of the Leslie Street Spit, home to Tommy Thompson Park and the Great Lakes' largest colony of cormorants, looks like a wintry apocalypse. There are no trees now, just a few guano-spattered snags. This is where cormorants first settled in the park in 1990. They now number about 30,000.

 

In some Ontario parks, Parks Canada officials shoot cormorants to stem the loss of trees. Wildlife defence groups argue about a hierarchy of values in nature: Are trees and the forest canopy more worthy than a colony of cormorants?

 

These widely unloved, fish-eating migratory birds are ruthless nest builders. With their hook-tipped bills, they strip tree branches; their guano becomes a hyper fertilizer, wrecking the chemistry of the soil. Trees die three to 10 years after the birds build their nests.

 

On Lake Erie's tiny Middle Island, in Point Pelee National Park, 20,000 cormorants have stripped away 41 per cent of the tree canopy. To reduce the impact on the island's nature life, Parks Canada officials went out with small-gauge rifles for six days in April and May and shot 1,600 birds.

 

A cull is not proposed on Toronto's spit. "We don't feel lethal control is appropriate or needed," says park manager Ralph Toninger.

 

But the rate of deforestation there is accelerating and it's a shocking sight. Four arms, or peninsulas, radiate from the spit. Peninsula A is treeless; Peninsula B, with its pungent odour of guano, has lost half its trees; and in Peninsula C, thousands of black birds perch in the trees like eerie ornaments. That area is losing trees 10 times faster than in the past.

 

"It's increasing exponentially," says Toninger. He notes the tree loss occurred when the cormorant population was one-quarter what it is today. Peninsula D is untouched.

 

Staff at Toronto and Region Conservation Authority try to encourage cormorants to build nests on the ground. They set up speakers playing recordings of cormorant calls (which sound like snoring), put out decoys, hay bales and tires. Now, 1,000 of the 7,000 nests on the spit are on the ground.

 

Still that's not reducing the numbers and that concerns people like Cathryn MacFarlane, who say cormorants should be controlled with humane methods, such as oiling their eggs. (Deprived of oxygen, the eggs don't hatch.)

 

"We have been supporting the conservation authority, but we're getting frustrated," says MacFarlane, on the board of the Aquatic Park Sailing Club at the east end of the spit. "Will someone please stand up and ask, why don't trees count? What about the songbirds?"

 

In other places, conservationists have tried to reduce cormorant numbers by poking at nests and introducing birds of prey. One of the most creative efforts is in Hamilton harbour, where cormorants were pushing herring gulls out of their nests, says Jim Quinn, behavioural ecologist at McMaster University.

 

Quinn employed a fleet of dancing, battery-operated Santas, sheathed them in raincoats and put them on the wildlife islands, in the harbour near gulls' nests. "The cormorants are declining a little in the harbour," says Quinn.

 

On Middle Island at Point Pelee, nine species are threatened or endangered. The ecosystem is considered so delicate that visitors are banned from May to September. The islands are critical for migratory Monarch butterflies as a refuge on their flight across the Great Lakes, says park superintendent Marian Stranak, adding that Parks Canada has a mandate to protect species at risk.

 

Their methods of killing cormorants were "controlled, humane and safe," she says.

 

A group called Cormorant Defenders International insists this is a matter of humans trying to manage nature. "We've come to the notion that trees are good and lack of trees is bad," says spokeswoman Julie Woodyer. "Why can't we see the beauty of a non-treed island if it happens to be a beautiful bird colony?"

 

"This is supposed to be a protected bird area, where people are prevented from going. If birds can't exist there in typical numbers, there is no place they will be tolerated. The exception is the Leslie Street Spit."

 

There, she says, Cormorant Defenders "pushed really hard" with the conservation authority on the need for cormorant management.

 

Should nature be allowed to take its course? Is intervention necessary to ensure a balance? Is shooting cormorants – once threatened themselves – the most civilized way to protect plant and animal life?

 

Ed Reid, wildlife biologist for the Ontario Federation of Anglers and Hunters, says cormorants, which eat about a pound of fish a day, should "absolutely" be culled.

 

The federation maintains that their numbers are an "ecological disaster in the making," media releases say.

 

"If human enterprise did to water quality what cormorants do, it would not be tolerated," says Reid.

 

At Tommy Thompson Park, declared an Important Bird Area by Nature Canada and Bird Studies Canada, 25 per cent of the trees have been destroyed and some birds, like the black-crowned night heron, are being pushed out. The number of herons has dropped from 1,200 pairs in 2001 to 500 today.

 

Leslie Street Spit, which receives 250,000 visitors a year, is man-made, built on the foundation of construction rubble. The trees cling to life on thin soil. Toninger looks at Peninsula C across a bucolic scene of red osier dogwood, giant bur reeds and sparkling water. If the trees weren't there, the birds wouldn't have nested.

 

Cormorants were once rare, too. Pesticides such as DDT thinned their eggshells and their numbers plunged.

 

But when DDT was banned, reducing lake contaminants, fish populations such as alewife increased, and the birds, able to feast in the fish farms in the southern U.S. where they overwinter, began to thrive.

 

In 1990, the first 11 pairs of cormorants nested on the spit. "It's amazing we see this," says Toninger. "Cormorants were pushed to (near) extinction in the '60s and '70s." Then he points to the city.

 

"There's the CN Tower and there's a bird colony. Where else can you see a nesting colony (not far from) a TTC ride?"

 

Julie Woodyer of Cormorant Defenders International witnessed this year's Middle Island cull from a boat. She wept at what she saw. Most carcasses were left where they fell.

 

"They are a part of a natural ecosystem, not a threat to it," she says. "They are being targeted because people find them unattractive and undesirable. People say they like to live with nature, but they like to look at nature not live with it."