Double-crested cormorants are pests. Every spring, thousands of the migratory birds fly north from as far away as Cuba, land in the Leslie Street Spit, and spend the next few months doing their best to wreck the place. After the lanky black waterbirds started coming in 1990, it took them only a decade and a half to leave a quarter of the trees in the park dead or dying.
The problem? “They’re excellent nest-builders, and they add to their nests all breeding season long,” explains Karen McDonald, a project manager with the Toronto and Region Conservation Authority (TRCA). That’s fine for the birds, but it’s hell on the trees. As the nests get heavier, the branches can’t support them and eventually give way. Plus, the cormorants do a lot of pooping—so much that it often coats the leaves below and makes photosynthesis impossible.
On a soppy day last month, McDonald was sitting in the back seat of a pickup truck being cautiously piloted by Nikita Moores, a TRCA crew leader. As we headed towards one of the park’s peninsulas, McDonald warned us that once we got close to the cormorants, we’d probably not only get pooped on, but puked on, too. “It’s a way to discourage predators from approaching their nest,” she said. “If you’re a raccoon and you’re looking for food and I barf up a fish in front of you, that’s a really easy meal that you can grab, rather than climbing a tree and attacking my nest.”
TRCA staff need to get close, though; it’s the only way to stop the birds from taking over. Near the nesting grounds, we walked past signs warning the public to stay out and into the middle of the colony, surrounded by trees dotted with nests. “At the beginning of the season, you go in and the birds see you and fly away,” said McDonald. But as the year goes on, it takes more work to scare them: TRCA staff have to yell, run, even set off firecrackers, all “deterrent methods” that they use to keep the cormorants from growing their territory any larger than it already is. They’ve tried artificial predators, too—decoys that resemble birds of prey, even kites that have big eyes on them—but it’s all gone “rather unsuccessfully,” according to McDonald. “It tricks them the first couple of times, but they quickly learn that that owl decoy is not gonna hurt them.”
Eventually, says McDonald, nothing will work. To prove it, Moores assembled a long aluminum pole and then smacked it against a tree a few feet away from where one cormorant was sitting. (It’s another deterrent method.) After a few thwacks, the bird reluctantly hopped out of the nest, but only to stand on the limb a few inches away. “I don’t think he’s going,” said McDonald, before Moores hopelessly hit the tree a few more times. “He’s not going anywhere.”