What are farmers shooting all day long?

Hi, apologies for the noob-style question. I have been living in the Northumberland countryside, near the coast, in a pretty rural area for a few years now. For the last five weeks, I've heard gunshots 8am-5pm. I am just wondering what on earth farmers can be shooting all day long... I thought there might be the odd shooting sound now and again, but not all day long, especially as pheasant open season is finished (If i'm not mistaken). I'm an animal lover and do a lot to help wildlife, and it just makes me so uncomfortable and upset knowing living creatures are dying or, worse still, being injured.