Bridge Baffles Birds

Ten years after Confederation Bridge opened to link Prince Edward Island with mainland Canada, migrating seabirds still have trouble getting past the lengthy structure.

It's not immediately obvious to many scoters that they could fly over or under the bridge.

Birders have noticed scoters on their fall or spring migrations being stopped by the bridge, as if it were a giant fence. Even though the bridge sits 40 metres above the waters of Northumberland Strait, scoters won't pass underneath.

About half the scoters encountering Confederation Bridge circle, gain height, and fly overtop. But a flock can make several attempts, approaching the bridge and then veering away, before some birds build the confidence to get past.

Often birds land on the water in front of the bridge, where they will stay for hours. Others fly parallel to the 13 kilometre-long span, heading towards shore.

A decade of observations reveals that seabirds haven't become accustomed to the giant bridge over time. In fall just over half (53 percent) of scoters on average fly directly overtop, while in spring only one-third (34 percent) do.