I am not sure what is happening. Yesterday evening, about 18.30 had a brief screaming fly pass with 6 swifts. Last night however both nests were empty all night. Today a brief view of 2 swifts flying high but still both nests remain empty. Nothing else to say at the moment but I will search the loft to see if there is any evidence of any more swifts but I am not feeling very optimistic.