(CNN) -- Dozens of animals, some of them rare, remained missing from Tasmania's only accredited zoo Saturday, two days after someone released the creatures into the wild, the zoo's co-owner said.
The intruder or intruders also killed about a dozen birds, including a Tasmanian swift parrot, said Rochelle Penney, who co-owns Tasmania Zoo with her father, Richard Warren.
The Australian government lists the bird as endangered.
Fewer than 1,000 of the birds remain in the wild, according to the Australian Parks and Wildlife Service. The death will affect the zoo's work to increase the bird's numbers, Penney said.
"It's very upsetting," she said.
The incident happened Thursday night. Warren found an enclosure door open when he arrived at work the next morning, Penney said.
"Then it went from there door after door," Penney said.
The entrances of about 30 enclosures had been flung open, she said.
The zoo sprang in to action to limit the damage.
"We had to quickly go through and lock them all up," Penney said. "We spent the last two days to recapture the animals."
Particularly painful was the release of the park's population of quolls, a rare indigenous mammal zoo officials were trying to replenish in captivity, Penney said.
Like kangaroos, quolls are marsupials and carry their young in pouches. But they are much smaller and crawl instead of hopping.
The zoo also has a Tasmanian devil breeding program, but those animals remained in captivity, Penney said.
Some of missing animals will die if not recaptured, Penney said.
"A lot of our animals are in captivity for a reason," she said. "They won't survive on their own."
Penney said she hopes that many animals will not go far, allowing them to be recovered.
"They know where home is," she said.
The incident has placed a financial strain on the zoo, which receives no government funding.
It will cost up to 2,000 Australian dollars ($2,111) to replace each of the birds killed in the incident, Penney said.
"We are privately owned and operated," Penney said. "It has taken us nine years to get where we are now."
The zoo "takes up about 15 -- 20 acres" and boasts a variety of animal life, but birds appear to be a particular specialty.
"We have over 80 species of birds," Penney said.
Tasmania Zoo has no idea who might be behind the rampage, hoping police will make progress or someone from the public will come forward with a tip.
Fans of the zoo have called to offer words of comfort, Penney said, but so far no leads.