3.3 Common Swift nesting site, Agnes Convent

The common swift originates from rocky areas. They see our buildings as one big rock formation. On their part, people realized that common swifts feed on insects. As early as the fifteenth century, openings for these birds to fly into buildings were specially made, for instance in the end wall (the cross) of the former Agnes convent in Elburg. Each bird brick is 12 by 12 centimetres and has a round opening of 3.6 centimetres for the birds to fly in. The cavity in the wall is 18 centimetres deep. For centuries, common swifts have been returning here every year, after wintering in Africa, to catch insects, including those that are harmful to humans.

-Agnietenklooster (Agnes Convent)

-Elburg (NL) 1418