What affects the population?

Answer 1

There are a few threats to the platypus's population.

The introduction of red foxes as a predator for rabbits may have had some impact on platypus numbers on the mainland. Feral cats are another platypus predator, but the platypus's principal enemies are humans. Humans used to hunt them for their fur, but they are now protected. The danger is now not from hunting, but from destruction of their environment. Also, the use of fishing nets in freshwater creeks and rivers resulted in large numbers being drowned, but this practice has been banned.

Natural predators of the platypus include snakes, water rats, goannas, spotted quolls, eels, hawks, owls and eagles. In the north of its range, dingoes are another predator. Lower platypus numbers in far northern Australia are possibly due to predation by crocodiles. On occasion, large eels have been thought to take platypuses, which may be only half the length of a freshwater eel.

Another factor which affects platypus populations is flooding. Young platypuses may be washed out of their burrows when floodwaters come, and few of these survive.

Tasmanian platypuses are subject to platypus fungal disease, or Mucormycosis. This fungal disease causes ugly skin lesions or ulcers to develop on various parts of the platypus's body, including their backs, tails and legs. These lesions become quite large, and are ultimately fatal. Death comes from secondary infection, and from the fact that the platypus's ability to maintain body temperature and forage efficiently for food is affected. It's not yet known how the disease spreads from platypus to platypus, but the mainland creatures are not affected.