Monday morning, Chicago Bird Collision Monitors fielded dozens of hotline calls from the South Loop reporting “tons” of baby birds lying on the ground surrounding one building in particular. Volunteers investigated, and to their horror and surprise, there were dozens of dead and injured baby seagulls. While it is not uncommon to see dead or injured baby gulls on the ground from their own beginning flight mishaps, numbers of this magnitude are highly unusual. Initial reports speculated that a human being had entered a rooftop colony and thrown babies and eggs off the building.
Volunteers set to work scooping up the injured birds and securing them for transport while other volunteers began the process of bagging and recording each dead gull. The Field Museum bird department planned to prioritize the examination of these specimens to see if a natural cause could be found. As seagulls are federally-protected migratory birds, US Fish and Wildlife Service was also notified, and they dispatched their people to investigate.
Working together, scientists determined that adult seagulls were attacking young from other parents, picking up the babies and dropping them over the edge of the building. They pushed eggs off the ledges to shatter on the ground below. In total, seventy
baby gulls were dead or injured. The twenty-five living birds were transported to Willowbrook Wildlife Center. To date, twenty-one of those have survived and are being cared for by licensed wildlife rehabbers.
As for the cause of the viciousness of the adults, the director of Chicago Bird Collision Monitors has theories. When competition for resources becomes fierce, instinct drives adults to kill off rival birds to assure the success of their own brood. It is also possible that the unusual and sudden changes in weather with thirty degree temperature swings or even poisons on the roof triggered the behavior.
Whatever the cause is ultimately determined to be, this is one of those sobering scenes that reminds us that while wildlife coexists with us, these are still wild animals. As Tennyson wrote in the 1800s upon reflecting on Darwin’s expedition, “Nature, [is]red in tooth and claw,” or in this case beak and wing.