A group of exotic birds have died at a zoo after eating rat poison.
Drusillas Park, near Berwick, Sussex, said 11 rainbow lorikeets were accidentally killed in their enclosure after a pest control company put toxic bait underground to catch rats.
A spokeswoman for the zoo said "very unfortunately" the birds ate some residual bait dropped by the rats.
The Eastbourne Animal Rights Action group was tipped off to the deaths by a whistle-blowing employee.
Group member Roberto Lopez said: "We were very concerned when we heard the news. This person has risked their job in coming to us, and they were right."
A protest was held by the animal rights group over the weekend, outside Drusillas. They also took issue with the decision to poison, rather than trap and release, the rats.
The zoo said it had called in the pest control company after five other lorikeets were attacked and killed by rats.
The spokeswoman for the zoo added: "This was an unprecedented situation with the rats becoming bolder and more numerous, and we made the decision that we had to take firm action.
"As a result of this situation we will be reviewing our procedures for pest control to ensure nothing like this ever happens again. This was a very unfortunate accident that has upset the entire zoo team."
Lorikeets are Australian forest birds, they mate for life and both male and female partners take dual responsibility in raising their young.