Whether we like it or not (and we don’t) as long as no laws are being broken and shooters have the landowner’s permission to be on the site, shooting some species of birds and mammals is currently a lawful activity and disrupting a lawful activity carries risk of committing an offence. Assuming no violence or criminal damage takes place (when the police will always be called by a shoot manager), this would usually be trespass or aggravated trespass. Trespass is a civil offence and it is up to the landowner on whose land there has been an incursion to decide on what action to take. On private land (and shooting almost always takes place on private land) trespass becomes a criminal offence of aggravated trespass the moment somebody tries to prevent another person pursuing a lawful activity. Again it is up to the landowner on whose land there has been an incursion to decide on what action to take.