Almost an entire flock of Bohemian Waxwing birds were killed after they flew into a glass structure in front of the Scouts Canada building in Ottawa.

Staff at Scouts Canada told CBC News the songbirds, which are sleek and measure about 18 to 21 cm long with a pointed crest, were feeding on berries last week when they were spooked by a transport truck's horn.

Some of the about 30 birds hit the glass, tent-shaped structure on Baseline Road and only five survived. They are currently recovering inside an incubator room from internal bleeding and concussions.

One bird is also now blind in one eye.

Prognosis improving for 3 birds

The birds are being cared for at the Wild Bird Care Centre in west Ottawa. Patty Summers, education coordinator at the centre, said the prognosis varies but the likelihood of recovery is high.

This tent-shaped glass structure was a barrier for a flock of birds startled by a transport truck last week. (Judy Trinh/CBC)

She also said it is odd for such a high number of birds to die from a crash into a structure.

"Three are looking really, really good. I expect they'll be released by the end of the week," Summers said.

"They're slowly moving into bigger and bigger cages. The one with the eye problem, he's going to be here a little while and there's one that still has some trouble breathing."

Scouts Canada staff members have begun to prune the berry bushes and trees so birds will not return to feed. But Summers said glass buildings should also have reflective material birds can see.