Bye-bye birdies

Bye-bye birdies

Billions of birds head south from Canada during their annual fall migration
September 25, 2013

Bridget Stutchbury is familiar with the tragic stories of songbirds dying in droves as they fly south each winter. But the CFI-funded York University ornithologist says the recent mass killing of about 7,500 birds was alarming, even for her. “The shock value here is there was a single event where thousands of birds were killed in an instant,” says Stutchbury. “It may have just been a bad coincidence — a night when migration was really heavy, the conditions were foggy and the birds had to come down because they couldn’t see the stars anymore. “

Many reports suggest that without the pinpricks of starlight guiding them from above, these flocks of birds were drawn to the only beacon by which they could navigate — a 30 metre gas flare spewing from the mouth of a tower at the Canaport LNG plant in Saint John, N.B. Red-eyed vireos, warblers and thrushes flew into the flame, an inadvertent sacrifice in the service of a biological cause: the annual fall migration.

Stutchbury says every autumn, three to five billion birds leave the treetops of Canada, their instincts compelling them to winter roosts in the southern states, Mexico, Central and South America. But their flight path is full of hazards, some freakish like the gas flare as well as other, more common, dangers.

For example, says Stutchbury, as birds fly between the skyscrapers, thousands take a fatal swerve into glass windows because they cannot detect the see-through surface. “In Toronto, they find about 3,000 birds a year,” says Stutchbury. “So if you scale that up, we can only assume tens of millions of birds are killed annually by flying into buildings and communications towers.”

Tens of millions more are taken out by pet cats, says Stutchbury. Migrants are tired and hungry by the time they settle in the small woodlots that are pit stops on their way south. While there, these songbirds are essentially sitting ducks for any sly feline slinking through the branches.

But Stutchbury says the main threat to migrating birds is the shrinking pockets of forests they use on their hop, skip and soar south. “These birds are pouring down from the north and they have to cram into fewer places,” says Stutchbury. “For them it’s like crowding into a Motel 6 on the highway when they would much rather be staying at the Ramada Inn.”

“I think it’s normal for migration to be challenging,” she adds. “But the reason so many of our songbirds are in steep decline is because this migration journey is nothing like what it was one hundred years ago.” Stutchbury says the combination of fewer habitats, cats and cities, along with the general challenge of spending several thousand kilometres on wing means that half of all birds migrating this season will not make the return trip home. She says these factors have pushed some of Canada’s most common songbirds — like the Canada warbler, Bobolink and even Barn Swallows — into threatened territory.

Pulling them back from the brink is no easy task. One of the greatest challenges for avian scientists like Stutchbury is knowing where most birds die along their migratory routes. But following a passerine that can fit into the palm of your hand is tricky. The solution? Technology. Stratchbury refers to one researcher — Martin Wikelski at the Max Planck Institute in Germany — who has developed “biologgers.” The devices patch into a satellite-based global tracking system that could be adapted to allow songbirds to be followed in real time. Think of it like an avian radar system, where researchers track birds blip-blip-blippping along on a screen. Something’s not right when dots continue to disappear in one location — a Bermuda Triangle for birds.

Stutchbury says once habitat hotspots are identified, people can begin working to turn the tide in favour of their feathered friends. In fact, that is exactly what she is doing in collaboration with organic coffee farmers in Nicaragua and Honduras. Stutchbury says she is helping them get the gold standard of organic coffee: berries grown under the shady canopy of trees that double as habitat for birds. Beans and birds — it’s a win, win, according to Stutchbury.

She goes further by suggesting people needn’t be bird biologists to help out. Simple efforts, like decals on windows, maintaining trees on their property and shooing cats indoors, can have a small but significant impact on the success of the annual migration. Collectively, these efforts add up to one goal: helping vireos, thrushes and warblers make their way south, safe and sound.