Bird-friendly Building Design Ordinance

The Problem

Every year, more than 100 million individual birds—representing over 250 species—fly through Chicago on their seasonal migration path in fall and spring. While they are here, they help control pests like rat and insects, pollinate food sources, and attract avid birdwatchers, who fuel the economy. Unfortunately, this city is one of the most dangerous places for birds to stop, forage, and rest on their way from their warmer homes in the south to habitats in the northern hemisphere where there’s more food and space, then back again.

One reason for this is that birds often collide with hard-to-see buildings across the city. They can’t perceive transparent or reflective glass as a barrier, and artificial lights that allow them to see open space or activity on the other side of a window make things worse. Those lights can also disorient them and send them off course.

In October 2023, nearly 1,000 birds died in one single night after hitting McCormick Place Lakeside Center (following this tragedy, changes were made to both building policies and 120,000 square feet of windows that reduced the incidence of bird collisions by 95%). But that’s a drop in the bucket; Chicago Bird Collision Monitors collect roughly 10,000 dead birds annually and up to a billion birds die each year in North American cities as a result of window collisions.