The birds were about two weeks old when they were stolen in two batches, several nights apart.
First, fourteen birds disappeared, with the remaining nine chickens taken a few nights later. They had been kept indoors, with a window so that children could see them.
Zookeeper Josefine Rees said the chicks had been very popular.
“The children love them when they are small and sweet. It makes you very cross and upset – why do people do things like this,” she said.
Rees says she hopes to have new chickens soon.
“But we probably won’t keep them there,” she said, adding that nothing of the kind had ever happened before.
“There has been graffiti and broken plant pots and such like, but we’ve never had chickens stolen,” she said.