Brambling 'mega flock' wows crowds in Switzerland

A huge flock of up to four million Bramblings has gathered in Switzerland this winter.

The incredible congregation, which is estimated to contain between one and four million individuals, gathers in the evening ahead of roost near Langenthal, in the canton of Bern in the north of the country.

The 'mega flock' of Bramblings at roost (Martin Meier).

The roost has naturally attracted predators, and is being repeatedly attacked by Eurasian Sparrowhawks, Common Buzzards and Peregrine Falcons.

During the winter, Brambling is nomadic in its search for food and is partial to the seeds of beech, birch and spruce. Occasionally, large flocks can amalgamate to create these so-called 'mega flocks'.

In the winter of 1951-52, a mega flock of Bramblings wintering in Switzerland was estimated to consist of 70 million birds. However, this has since been disputed and the true total is now thought to have been 36 million – still an extraordinary number.

One recent mega-flock event consisted of roughly 5 million birds in the Zasavje Hills of central Slovenia during the winter of 2018-19, which frequented an area of only 10 ha.

The large gathering of finches has attracted predators (Martin Meier).