Webcams across the country were switched on at the weekend to mark the start of the annual armchair birdwatching campaign Beleef de lente (experience spring).

Bird protection society Vogelbescherming has some 24 nesting boxes equipped with cameras which monitor the nests of over a dozen species.

Among the first birds to lay eggs are the tawny owl, the little owl, the barn owl and the white tailed eagle. The birds can be watched 24 hours a day until the last young leave the nest around the end of July.

This is the 18th Beleef de lente which attracts over a million bird lovers a year. Locations are kept secret, although there are people who find the cameras intrusive, Vogelbescherming spokesman Louis van Oort told NPO nature programme Vroege Vogels (Early birds).

“We leave them in peace. The camera doesn’t disturb them at all. That is the point,” he said.

The images can provide new insights into the lives of the birds, he said. It was long thought the tawny owl female looked after the chicks but when the female of a pair was killed by a marten the male was on his own.

“Initially he was a bit nonplussed. But after a while he settled on the nest. Those chicks had to be kept warm, after all. That event ended up in a scientific paper,” Van Oort said.