It is early for Jackdaws to start nest building, but their instincts are definitely stirring.
Hole number one, check
Hole number two, check
Hole number three, check
The individual on the left (prob the male), makes some soft calls with plumage fluffed up
The curious Carrion Crow watching the Jackdaws
Coombs, F. (1978). The Crows: a study of the Corvids of Europe 255 p. London: Batsford.