No birds in our garden

We have a garden of about an acre with plenty of trees, shrubs, flower beds and lawns but we haven’t had any birds in it for several weeks. We live in a small town but always had an excellent selection of birds - the usual ones such as blackbirds robins sparrows jackdaws chaffinches, pigeons . Have they just reduced, is there any disease going around? Can you suggest why?

resident, NN9 Northamptonshire