Author Sir Terry Pratchett has increased the reward to catch the killer of 31 swans near Burnham-On-Sea to £26,080.
Supporters of Secret World Wildlife Rescue originally provided £16,080 as a reward to find the culprit.
On Wednesday, the reward was further increased by £10,000 when fantasy writer Sir Terry Pratchett (pictured) said he was “incensed” at the deaths after a further ten swans were found shot with an airgun near Wedmore, bringing the total to 31.
Sir Terry, author of the Discworld novels, added: “It’s wanton destruction of a living creature. People who do this sort of thing to an animal are probably a danger to people as well.”
“I don’t think the punishment will fit the crime. For some idiot to fire an airgun for fun – I was just incensed. I’ve seen the sanctuary, I’ve lived in Somerset and I know the area.”
Secret World described finding the first eight shot birds on 22nd February as “one of the worst incidents” it had ever dealt with.
The birds had been shot in the head with airgun pellets. One of the swans which survived an earlier attack is still recovering at Secret World’s centre in East Huntspill.
Secret World said contributions to the reward, leading to the conviction of those responsible, were coming in from all over the country. There have been three donations each of £5,000 from anonymous donors, £10,000 from Mr Pratchett and £1,080 from the general public.
The police are assisting the RSPCA investigation and said extra patrols were being carried out by their neighbourhood team.