It might be hard to imagine, but cats kill an estimated 100 to 300 million birds in Canada each year; one wildlife expert says that’s about five per cent of all birds in the country.

Those are the stunning findings of a study conducted by 20 researchers led by Dr. Richard Elliot, an Environment Canada biologist specializing in bird biology.

Elliot says cat kills are roughly equal to all sources of other bird kills combined.

"That includes strikes with cars, buildings, telephone wires,” says Elliot.

The study estimates that urban housecats kill somewhere between 10 and 15 birds each year. The number doubles to between 20 and 30 birds each year for rural housecats.

For feral cats it doubles again, in the range of 40 to 60 birds per year.

"There's a tendency to think that the birds that cats prey on tend to be starlings or house sparrows, that we're not as concerned about as our native species, but the studies we were doing show that 80 per cent of them are native species in Canada that we are concerned about,” says Elliot.

About four million housecats in Canada have access to the outdoors and there's another one to four million feral cats across the country.

Hope Swinimer of Hope for Wildlife sees the victims firsthand. She and her staff are currently trying to rehabilitate a chickadee that was attacked by a cat.

"Cat bites are difficult to treat and we get a lot of birds in for that reason, and it’s not just the bite and the stress,” says Swinimer.

“A cat's mouth has a lot of bacteria in it so the first thing we have to do is start them on two different types of antibiotics plus pain meds right away."

“If we could just reduce the amount cats that are going outdoors, we could really save a lot of birds,” says Elliot.

Both Elliot and Swinimer agree the problem and solution begins with humans, and not with wildlife.

“It’s not a cat or a wildlife problem. It’s a human problem,” says Swinimer. “And as an ambassador for people who care about living things, we have a responsibility to try and come together and come up with a plan.”

With files from CTV Atlantic's Jayson Baxter