House Martins - NOT amateur radio

Usually, we see very few of these migratory birds. However, today there must have been 20 odd around the windmill next door.

They don't fly south for several months. Perhaps they were young ones?

Swifts usually leave soon, staying a few months only to breed. We saw a few yesterday.

See https://www.rspb.org.uk/birds-and-wildlife/house-martin .