Just a few days of biting cold may already have cost Denmark 25 percent of its smallest birds, including species such as the goldcrest (fuglekonge), Eurasian wren (gærdesmutte) and European robin (rødhals), all of which are especially vulnerable to cold temperatures.
“If this extreme cold continues throughout the month we will lose 90 percent of these bird species,” said Morten DD Hansen, a nature guide and curator at the Natural History Museum in Aarhus.
The goldcrest is Denmark's smallest and most cold-sensitive bird, but the other two species are nearly as small and just as vulnerable to freezing temperatures.
On extremely cold days like the ones Denmark is now experiencing, small birds use all of their energy to keep their body cores from freezing. While their body fat helps to insulate them, they have trouble maintaining it without adequate calorie intake. And that is difficult as their primary food sources – spiders and insects – also die off in the cold. Without enough food, small birds’ chances of surviving freezing winter weather are extremely limited.
If the deep freeze continues, dead birds could become a common sight, according to Hansen, who explained that they freeze, especially during the coldest hours of the night, and fall dead to the ground.
This year is not the first time that Denmark's small birds have died off in large numbers due to the cold.
“Last year's hard winter cost about 90 percent of these bird species,” said Hansen.
Daytime temperatures today are predicted to hover between -5º and -8º C and night temperatures could fall to -15º. According to weather service DMI, the cold spell will last through early next week.
One of the best things people can do to help small wild birds survive the cold, according to birding society Dansk Ornitologisk Forening (DOF), is to put out fatty and nutritious bird food in winter. Bird seed mixes and bird seed balls fortified with lard are good options, says DOF, as are whole apples.
