Glass buildings kill an estimated 1 billion birds annually in North America alone through window strikes. Simple, low-cost interventions dramatically reduce collision mortality for both rare and common species.
Window strike welfare harm is immediate and often fatal - birds who strike glass at speed experience head trauma, internal bleeding, and broken bones. Birds who survive initially may die hours later from internal injuries. The scale of the problem - billions of birds annually - makes window strikes one of the largest anthropogenic wildlife mortality sources. The welfare solution is well-documented and available: visual markers on glass surfaces at 2-inch spacing deter birds effectively, and interior light reduction during migration prevents attraction to buildings. Many municipalities have enacted lights-out programs during migration that have demonstrated effectiveness. Individual homeowners can significantly reduce collisions at their own properties through simple, affordable products.