On 4th August 2020, while examining a series of artificial nestboxes for second broods of House Martins Delichon urbicum at an upland farm in north Northumberland, I found a full-grown juvenile sitting on a nest containing three eggs and one recently hatched young. The box had previously been used by a pair of House Martins to raise three young, which were ringed and fledged on or around


Stay at the forefront of British birding by taking out a subscription to British Birds.

Subscribe Now