The forest floor harbours many large and small rodents and marsupials who advertise their presence by their sounds. You might hear a soft rustling through the leaf litter, digging and scratching, chewing noises, twigs snapping or the thump of hopping feet. If you proceed very quietly along established walking tracks, you could see a melomys or a native rat darting across the track or a family group of red-legged pademelons (Thylogale stigmatica stigmatica) sitting and listening before vanishing into the foliage. Many of these creatures can be very evasive, so you will need to be quiet. Some are nocturnal so you might need to go out with spotlight.
In the morning look for the musky rat-kangaroo (Hypsiprymnodon moschatus), a very dark brown marsupial macropod 
(kangaroo family) whose body is only about 23cm long, foraging for fruits on the rainforest floor. This animal is regularly seen around the volcanic Lakes Eacham and Lake Barrine and around the bases of the famous Curtain Fig and Cathredral Fig trees on the Atherton Tableland.
The musky rat-kangaroo prefers the wetter parts of the forest and feeds on fallen fruits found in the leaf litter as well as small invertebrates such as earthworms and grasshoppers. They give birth to two or three babies which stay in their mother's pouch for about 21 weeks before emerging to spend most of their time in their forest floor nest. When they are a little older, they will accompany the female on her feeding rounds.
Another interesting but very rare ground-dwelling mammal is the northern bettong (Bettongia tropica). The northern bettong occurs in upland grassy eucalypt woodland and tall open forest on granitic soils on the western edge of the Wet Tropics. It is a delicately built, rabbit-sized, rat-kangaroo with a prehensile tail used to carry nesting material. It is a nocturnal animal, sleeping during the day in well-concealed nests. Northern bettongs primarily feed on the underground fruiting bodies of mycorrhizal fungi (truffles), which they get by digging with their forepaws. Grass, roots, tubers, and lilies form an important component of the diet in drier areas, while forbs and invertebrates are also eaten in small quantities.
While most rodents will make a hasty retreat from human visitors, one not so easily intimidated is the giant white-tailed rat (Uromys caudimaculatus). This large rat has a body length of 30cm and the end half of its 33cm tail is white and without fur (which is the easiest way to identify them). The giant white-tailed rat can be seen on the forest floor at night but it is just as likely to be seen climbing around tree branches. Although most rodents are known for their powerful teeth, this one is particularly strong and can eat through the hardest of seed coats. The next time you find a coconut on the ground with a perfectly round hole about 2cm in diameter drilled through it, you will know that a giant white-tailed rat found it first!
Another ground-dweller, the quoll is quite the predator - an attractive but elusive night-time hunter of both the forest floor and the canopy. There are two species of quoll in the Wet Tropics: the northern subspecies of the spotted-tailed quoll (Dasyurus maculatus gracilis) and the smaller northern quoll (Dasyurus hallucatus). They are well known for their aggressive dispositions, described in books as pugnacious, ferocious and savage. The quolls are carnivores, preferring rodents, small macropods, birds and reptiles, although large insects, some fruit and even carrion is included in their diet. The quolls are not standard marsupials in that they don't have a real pouch. During breeding season, the skin around the female's nipple area extends into a flap which partially covers the young. Females have six teats, but the number of young born can range from one to eight. Young remain in the pseudo-pouch for several weeks before being left in a nest hollow or cave and attended to by the female. Independence is usually reached by 18 weeks and sexual maturity is at one year.
There are many other mammals to look for in the Wet Tropics such as the melomys (native rat), hydromys (the water rat whose fine swimming abilities evoke images of the river otter), northern brown bandicoots (often seen darting across roads at night, or squashed on the road), their paler rainforest cousins the long-nosed bandicoot, agile wallabies (look for them hanging around the golf courses of the northern beaches of Cairns), and the adorable red-legged pademelon.
You can find out lots more about ground mammals in the following fact sheets:
