The birds were shot at Norton Mills lake in North Stainley, which could have put people's lives at risk as well.
Police say the eight geese and swans were shot and left to die.
More top news
X Factor judge Cheryl Fernandez-Versini has hit back at media reports criticising her weight.
A look ahead at the forecast for the Tyne Tees region.
The Met Office confirm this summer has been cooler and wetter than average