Glass collisions kill entire flocks of waxwings in Helsinki region

An unusually large number of waxwings have died after hitting glass buildings in the Helsinki region this autumn, Yle reports. Up to 150 dead birds were found at the Viikki campus in Helsinki.

Saara Fredriksson of Helsinki Wildlife Aid Association said volunteers had found large numbers of dead birds, including entire flocks. The birds had flown into glass structures at Viikki, and dozens were also found dead near Ainoa shopping centre in Espoo, according to Helsingin Sanomat.

Waxwings have also collided with high-rise buildings in Jätkäsaari, Helsinki, where they had gathered to feed on rowan berries. Dozens of injured birds are being treated by the Capital Region Animal Welfare Association, Fredriksson said.

The birds are moving south from the north in large flocks to spend the winter. They are less accustomed to buildings than birds that live in cities, Fredriksson said. She added that there is conflicting information about whether fermented rowan berries can intoxicate birds. A bird lying on the ground should be treated as injured and helped, she said.

How to help prevent collisions

Fredriksson said cities should take birds into account when planning construction, particularly around tall buildings and reflective glass surfaces. She recommended keeping blinds closed, drawing patterns on windows with UV pens that birds can see, and leaving windows unwashed so they are less clear. She also advised against planting berry bushes or rowan trees next to tall glass buildings.

Bird expert Juha Laaksonen said on Yle’s Luontoilta programme last week that waxwings had already reached Finland’s southern coast and were now present across the country. Their strong flight response can cause them to dart into windows or walls near berry trees, he said. The supply of rowan berries varies from one region to another, plant expert Henry Väre said on the programme.