Ms James said vets first came to the sanctuary after several ducks suddenly fell ill and passed away.
They initially thought it was a toxicity case, but then turkeys and cockerels were affected.
Testing by Animal and PLant Health Agency then confirmed the presence of the virus.
Ducks, geese, chickens, seagulls, a rhea, pigeons and pheasants are among the other birds to be culled.
“I don’t think in all my 10 years of running the sanctuary and keeping birds, I’ve ever had a more devastating blow,” said Ms James.
“This has ripped mine – and all the crews – hearts right out.”