The city of Chicago has recently witnessed an unusual and strange case involving the death of thousands of birds and a glass-enclosed building.. In a single night, more than a thousand migratory birds died after accidentally crashing into the windows of the McCormick Place Lakeside Center convention center, located on the shore of Lake Michigan.

The events occurred in the early morning of October 5. That morning, workers from the Field Museum in Chicago collected more than a thousand dead birds next to that building, to which must be added another thousand birds collected in the city center by volunteers from the Chicago Bird Collision Monitors association.

“It was overwhelming and tragic to see so many birds,” said Annette Prince, director of this local organization that monitors birds in the city, in statements to CNN.. “I went to a building and when I walked in, it was like there was a carpet of dead, dying and injured birds,” he described.

Experts are now trying to explain this extraordinary number of fatal bird collisions in such a short time, but everything points to a combination of factors.

According to Prince, there was a particularly high volume of birds migrating south for the winter that night, as they had been waiting for northerly or westerly winds to ease their journey.. “They piled up,” Prince said.

To this we must add “foggy conditions and low clouds, which can be confused with lights and buildings”. According to Prince, the presence of clouds probably caused the birds to fly at a lower altitude, so they got too close to the buildings.. Additionally, the McCormick Place convention center “is one of the first buildings that birds encounter as they move along Lake Michigan.”

The fact that these types of buildings leave the lights on at night encourages collisions, since “they are an attraction for birds, almost like a lighthouse,” says Prince.

Another factor to take into account are the large transparent glass panels, which these animals confuse into believing that it is an open space.

For Andrew Farnsworth, an ornithologist at Cornell University who studies bird migration, this collision of migratory birds was “of enormous magnitude.”. In an interview on CNN, the expert indicated that the number of birds killed in the McCormick Place building that night is equivalent to the usual number of deaths from collisions with buildings in a year.

For this reason, this case has been “something very strange and quite unfortunate,” Farnsworth said.