Black Sun is a natural phenomenon that can be experienced in spring and autumn, when enormous flocks of black starlings, sometimes hundreds of thousands, create fascinating patterns in the sky, virtually blocking out the sun. The aerial ballet can be seen at sunset, when the birds leave their feeding places and take flight before they settle in for the night. The scene becomes even more spectacular when birds of prey are drawn to the marsh, eager to hunt the starlings. Their arrival causes the starlings to fly in ever-changing wavelike formations in the sky.
The phenomenon can be seen in several places in Denmark, but you’ll find the largest gatherings of starlings around Tønder Marsh in southern Jutland. There is no way to say precisely where the birds will perform their twilight ritual. They may move from place to place. It’s best to visit the marsh with a nature guide or on a group tour.
During migration, the starlings come to the marsh to gobble up spiders and insect larvae they find in large quantities in the damp grassy marshland. During the day they search for food and at night they sleep in the shelter of the reeds.
Black Sun occurs twice a year – from the middle of March to early April and again from the middle of September to the middle of October. During the season, the activity starts about an hour before sunset and continues for about 20 minutes.