• The Issue

A Brief Primer on the Bird-Building Collision Issue

Chances are, you’re here because you care about birds and want to take action to protect them. Birds are in trouble, and many species are declining steeply and rapidly. We need to act now.

This page offers a brief primer on the issue of bird collisions with glass to give you the facts you need to speak up for birds on campus.

Universities & Colleges

Dark-eyed junco | Photo by Michael Mesure

Migratory birds make astounding seasonal movements each year, some travelling thousands of kilometres each way between their northern breeding grounds and wintering grounds in the tropics.   Birds now have the added challenge of coping with all the cities and structures that have been built along their migration routes.

Many songbirds, including warblers, vireos, thrushes, and sparrows, migrate at night. Light pollution from urban areas can throw birds off course, drawing them into and trapping them in a maze of tall structures and glass.

During the day, migrating birds need to find places to rest and refuel. Urban parks, woodlots, and even your campus can be attractive places for a tired and hungry migratory songbird to stop.

Although collisions occur year-round, they are most frequent during the spring and fall migratory periods, when birds are forced to navigate through unfamiliar urban environments.

Collisions with glass are one of the most significant sources of direct, human-caused mortality for birds, affecting young and old, common and endangered species alike.  Recent estimates suggest that 16-42 million birds die each year in Canada alone by colliding with glass.  Estimates in the United States suggest that close to one billion birds are killed annually by window collisions.