Right...but that isn't necessarily the reason.Platypus are very easily stressed and are very difficult to keep in captivity. They are also immensely difficult to transport, as the shock and stress can kill them. Even in Australia there's only a handful of places that keep them in captivity. The fact that they are nocturnal makes them a bit more hard to keep as well, and the San Diego Safari Park switches night and day inside the Platypus house to keep them living as if they would live in the wild.
It pretty much comes down to the captive Platypus breeding program within Australia not being as established as you would hope.
are the more expensive to feed then a lion?This combined with the fact they're considered very expensive to feed. If the population in Australia was a bit more robust it's possible a few bigger zoos might be interested. San Diego's case happens to be that they are capable of devoting time and resources and had a strong connection to Aussie zoos to facilitate the transfer.
I remember the keeper talk at Healseville mentioning it costs roughly 13 k to feed them every year. They eat about 20% of their body weight everyday so combine that with the sort of food they eat (yabbies, worms, shrimp ect.) it does come to a hefty amount.This combined with the fact they're considered very expensive to feed. If the population in Australia was a bit more robust it's possible a few bigger zoos might be interested. San Diego's case happens to be that they are capable of devoting time and resources and had a strong connection to Aussie zoos to facilitate the transfer.