Dingoes are the main predators of kangaroos. But the reason they do so well now is because people chop down trees and make huge areas of grassland to graze sheep and cattle on. In addition to the free grass, humans have water sources for livestock, which the kangaroos use. This lets the roos breed all year round and they breed out of control.
If there wasn't as much grass, or a constant water source, they would only breed once a year instead of all year round.
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The meat is very low in fat (most fat is stored in the tail and used as a reserve by the roos in harsh conditions). The meat is also dry due to low fat and it needs a source to make it go down easier. But the flavour isn't bad. I used pureed carrots on kangaroo steaks, the carrot improves the flavor and makes it easier to swallow.