Sunday Magazine23:07Sunday Documentary: The Mystery of the Cormorant
It's safe to say that double-crested cormorants are causing a stink—in more ways than one—on the Toronto Islands.
They poop all over the place, which turns people off. And because this feces is acidic, it also bleaches and destroys the trees in which they nest.
“Rome is burning and the bureaucrats are fumbling. Every year it gets worse and worse, with more carnage and more trees dying,” said Warren Hoselton, who has worked as a park ranger on the islands for more than two decades.
“We manage the Canada geese, we manage the beavers, and we let these guys do it.”
About 18,000 double-crested cormorants make Hanlan's Point their home, close to the public jetty. According to the Toronto and Region Conservation Authority (TRCA), the population has tripled in the past year.
Those who live and spend time on the islands want to be resettled. But it's not as simple as it seems.
What's so bad about these birds?
Bird droppings, called guano, are responsible for transforming what was once filled with trees, greeon the coastline into something you'd see in a dystopian movie.
And in this one, the villains are the cormorants.
“It's hard not to call this an apocalyptic scene for the forest,” said Gordon Ballantyne, general manager of Toronto Island Harbour.
Ballantyne says he has seen up to 140 boats docked at the public jetty at Hanlan's Point on the long weekend. But this figure has dropped significantly thanks to cormorants minding their own business.
“People go to bed, wake up, and their boat is covered in, well, what the cormorants drop,” Ballantyne said.
What is the story of their origin?
The cormorants are believed to have come from another colony that lives just a few wingbeats away in Tommy Thompson Park on mainland Toronto, east of the islands.
While TRCA cannot be sure, the contingent's arrival on the Toronto Islands in 2022 coincided with a population decline in Tommy Thompson Park.
The group says some of the birds may have moved because there are more predators on the mainland, which consider the nest of cormorant chicks to be a tasty midnight meal.
“The raccoons, when they come to the colony, don't grab the bird and then take it out of the nesting area. They just sit in the nest and eat the chick,” said Gail Fraser, an avian ecologist at York University who monitors the colony at Tommy Thompson Park.
This stress may be the reason the cormorants move away, she said.
What can be done?
In some locations across Canada, including Ontario, cormorants can be killed. But because the pack lives within the city limits of Toronto, the ordinance protects them from being shot.
TRCA, working on behalf of the City of Toronto, monitors approximately 30,000 birds at Tommy Thompson Park.
He's willing to let nature decide the size of the colony, but what he doesn't want is cormorants nesting in trees because their feces are very destructive. Since the birds don't mind nesting on the ground, TRCA has to convince them to leave the branches and do so.
And it requires a lot of convincing. During the seven-week breeding season in the spring, staff spend hours yelling at cormorants in an attempt to get them to leave their nests. When this no longer works, they use pyrotechnics to scare the birds away.
“When you're in the middle of the season and the weather is bad and it's raining and … you're standing under cormorants and they're pooping and regurgitating fish on you, it's a complete mess,” said Andrea Creston, TRCA senior project manager.
Conservation groups near Big Rideau Lake say hunting native shorebirds is unethical and unnecessary. But from September 15, hunters are allowed to kill up to 15 animals per day. CBC's Stu Mills reports.
They then make nests in trees 80 to 100 feet high. But this is not always a permanent solution.
“So not only is it physically demanding, but it’s also emotionally demoralizing,” Creston said.
“You say, 'Yes, I've removed this many nests on any given day.' And the next day you return, and the birds rebuild their nests. So you constantly have to redo very hard work.”
But it was successful. In 2008, only 15 percent of the Tommy Thompson Park colony nested on the ground, according to TRCA. By 2024, this figure will reach 90 percent.
Why protect cormorants?
Not everyone sees the cormorant as a feathered villain. First, they are native to the region and not invasive.
Creston says that although they have a reputation for eating fish, According to a study conducted in the USA in 2003birds don't actually hurt overall stocks.
And Fraser says it's important to realize that while cormorants have done a fair amount of damage to trees in the area, they are not the harbingers of death they appear to be.
Yes, their feces are responsible for the destruction of forests. But Fraser says it's not habitat loss. This is a transformation of the environment.
“Habitat loss is when you build a parking lot and a home improvement warehouse, right? That's habitat loss,” Frazier said.
“Where we stand was once a forest. And now ring-billed gulls can nest here on the ground because it's no longer a forest. So it just creates habitat for other species.”
Possible solutions
Creston says the TRCA is using the same tactics on the Toronto Islands as it did at Tommy Thompson Park.
But on the islands, the entire colony nests in trees, and since there is no place for them to nest on the ground without first destroying the trees, all TRCA can do is try to force them to leave. During the breeding season, Creston and her team work from morning to evening, every day, trying to scare the birds away.
TRCA is trying to lure cormorants to Tommy Thompson Park with what are called cormorant flats—essentially a wooden structure without walls equipped with a predator guard to keep hungry raccoons away.
TRCA field staff also destroy cormorant nests on the islands. And Creston says the population has been declining for several years. But then, in 2024, eagles nested in the middle of the cormorant colony, making it a protected area.
Creston and her staff could no longer disturb the cormorants or knock down their nests in the area immediately around the eagles, and the cormorants flocked there. The population jumped again.
Fraser supports the work of TRCA. She says it's more humane than many other places in Canada that have decided to kill birds.
But she has another idea. It offers a completely new resting place for cormorants: a bird barge.
About 30 years ago, the city of Hamilton built three islands to address its own bird problem, a $2.4 million effort that has proven to be effective.
TRCA is “in the early stages of research” on floating habitat, Creston said. She says they are constantly adapting their management plan, but it will be years before they can relocate all the cormorants.
“Because our landscapes have been so altered by human activity, nature has remained limited,” Creston said.
That's why she wants them to move to Tommy Thompson Park, “where there's plenty of habitat and good habitat for them. Where they won't continue to reduce overall biodiversity.”
