Some 70,000 animals across Indonesia are at risk of starvation as zoos struggle financially due to social distancing restrictions amid the coronavirus pandemic.
A survey released by the Indonesian Zoo Association concluded that 92 per cent of its member zoos on the islands of Java, Bali, Sumatra, Lombok and Borneo had only enough supplies to feed their animals until mid-May.
Some 60 animal parks across the archipelago attract around 50 million visitors each year but, with most of them closed since mid-March, the body warned that thousands of animals are at risk, including endangered Sumatran tigers and Bornean orangutans.
"Not all zoos receive money from the government. Some are privately owned and rely on the revenue from ticket sales," said Indonesian Zoo Association spokesman Sulhan Syafi'i, as quoted by the Jakarta Post.
"If a few more months pass and we don't get any aid from the Government or other international organisations, then with a heavy heart we'll have to feed herbivores … to the carnivores," Mr Syafi'i told AFP.
"We've had to rely on creativity to survive," he said.
Some zookeepers were feeding carnivores chicken rather than red meat, Mr Syafi'i said, even using their personal chicken stocks to feed the animals.
They were also collecting grass and other plant matter to feed to giraffes and other herbivores, Mr Syafi'i said.
"We can put down wildlife that is not endemic [to Indonesia]," Mr Syafi'i said.
"But for wildlife endemic to Indonesia, like Sumatran tigers, we must do whatever it takes to save them. It's sad, but at this point, we need to start thinking about priorities."
A number of Indonesia's native animals including Sumatran tigers, orangutans and the Sumatran elephant are critically endangered due to poaching and habitat loss.
The Indonesian Zoo Association last month called upon President Joko Widodo and his Government to act to assist zoos and conservation centres to weather the outbreak.
Indonesia has been hard-struck by coronavirus, with the official number of infections more than 10,000 and a death toll of 1,665.
Many health experts believe that due to low rates of testing, the true number of infections is likely much higher.
Conservationists have warned that critically endangered orangutans are especially vulnerable during the COVID-19 crisis, as they are potentially at risk of contracting the disease.
Given genetic similarities, great apes are susceptible to respiratory diseases found in humans.
As a result, a number of sanctuaries in Indonesia shut their doors to the public early on in the pandemic.
"There haven't been any confirmed cases of direct transmission, but it's caused other issues like a shortage of masks and disinfectant supplies for our orangutan caretakers," said veterinarian Agus Irwanto of the Borneo Orangutan Survival Foundation in a statement.
Employees working closely with orangutans have been temperature-tested twice a day and are required to take leave if they feel unwell, the Foundation said.
As elsewhere in South-East Asia, Indonesia's zoos are notorious for animal cruelty.
Bandung Zoo in West Java province came in for widespread criticism in 2017 when footage showed emaciated sun bears dancing for food from visitors.
It came after the zoo was temporarily closed following the death of a Sumatran elephant known as Yani, found with bruises on its body.
In 2013 the ABC reported that 50 animals died in three months at the Surabaya Zoo, including an orangutan, three tigers, and a giraffe.
At the time it was dubbed the "zoo of death".
