The Kangaroo is a common animal in Outback.
The Kangaroo's pattern is 4 tiles in a diagonal pattern. This makes them easy to find, as there are only really 4 possibilities.
Because of how easy it is to find them, Kangaroos are respectively found in the "Common" category. This makes them easy to obtain and, with mass amounts, can earn a reasonable profit for such an easy animal to rescue.