In response to my well-meaning friend who was attempting to comfort me after my first dead sapsucker, no. Birds do not collide with glass because of some evolutionary design flaw or Darwin’s “survival of the fittest.” On the contrary: migratory birds found dead in Chicago are often exemplars of their species, the strongest and most resilient birds of their flock to make it this far. Imagine birds weighing only a few ounces having successfully flown thousands of miles from places as far as Peru, surviving pollution, predation, storms, starvation, and other threats only to meet their death in a preventable collision with building glass. While local, non-migratory birds usually learn to avoid glass, migratory birds are only passing through, and they do not have the benefit of extensive experience with buildings with glass façades. Migratory birds do not call urban areas their home; they normally live in rainforests, open prairies, woodlands, and wetlands. They have been migrating along these same routes for tens of thousands of years, while the hazards of lights and glass came about only within the past one hundred years.
We know from the City of Chicago, as well as independent scientific studies, that we never see most of the injured or dead birds. Some morning building maintenance crews clear many birds away, often power-washing living animals right into the street. Seagulls and crows that have developed a taste for migratory birds swoop down and scoop birds up whole, devouring them live in a particularly grisly display of avian adaptability to human habitat.
Birds are a critical link to balancing native ecosystems. They pollinate plants, eat billions of insects, control rodent populations, disperse seeds, scavenge carcasses, and recycle nutrients. Bird populations also serve as biological barometers for documenting climate change, monitoring habitat health, measuring urban noise, and recording changing weather patterns. Yet, despite their importance, many bird populations are in serious decline from manmade causes. Scientists are continuing to find that birds designated as conservation concerns such as the golden-winged warbler, painted bunting, Canada warbler, wood thrush, and Kentucky warbler are disproportionately represented in building kills.
Recent history demonstrates what can happen when humans devastate bird populations. The Great Sparrow Campaign enacted by Mao Zedong in China was a misguided attempt to protect grain crops and resulted in the extermination of hundreds of millions of insect-eating tree sparrows. When drought and poor weather took hold of the country, the meager crops people managed to grow were devoured by locusts and other grain-eating insects. A devastating famine took hold of the land and killed an estimated forty-five million people. Will we allow something like this to happen again?
Tomorrow, I will explain what our group has done to help rescue the injured birds for rehabilitation and recover the dead ones for scientific study.