Travelling anywhere in Kakadu, you cannot help noticing the lowlands - they make up nearly 80 per cent of the park. Appearing to consist mostly of eucalypts and tall grasses, they may seem lifeless at first glance. However, the woodlands support a greater variety of plants and animals than any other habitat in Kakadu.
At first glance, there appears to be little activity in the lowlands, yet they are in fact the richest of all Kakadu's habitats in terms of animal numbers. They contain a wealth of bird life, especially along the watercourses. Honeyeaters and parrots are particularly common. Red-collared lorikeets, red-winged parrots, red-tailed black cockatoos and sulphur-crested cockatoos are more often heard before they are seen.
The pale-coloured northern rosella is more commonly seen during the wet. An ever-present woodland sound is the 'doodle-doo' of the peaceful dove. The ground-dwelling partridge pigeon, with its distinctive red eye patch, is now largely restricted to the Kakadu area and is often seen along park roads. Finches, the black-tailed treecreeper, the whistling kite and the black kite are all common. The evening is usually announced by the raucous call of the blue-winged kookaburra, while at night the distinctive 'woof-woof' of the barking owl can often be heard.
The fine-featured agile wallaby is often seen feeding at the roadside in the north of the park. Dingoes are also often seen crossing roads. Wild dogs thought to have arrived in Australia with people about 5000 to 6000 years ago, dingoes have spread throughout the Australian mainland; they hunt a wide variety of small animals and feed on carrion.
Among the nocturnal mammals of the lowland woodlands are the flying fox, the brush-tailed phascogale, the fawn antechinus, the sugar glider, the northern brushtail possum, and the black-footed tree rat. The northern brown bandicoot builds daytime nests from grass and comes out at night to dig for roots and insects. Less commonly seen of the mammals are a number of native mice and rats. Even though many nocturnal animals might not be seen, their tracks, diggings and droppings provide evidence of their activities.
Of the reptiles, Gould's goanna, with its yellow-green throat, is often seen stalking through the woodlands. On the forest floor skinks scuttle through the leaf litter looking for insects. The largest skink is the northern blue-tongue, but perhaps the most eye catching is the fire-tailed skink, with its bright-red tail. Non-venomous olive, carpet and children's pythons are most often seen at night on the roads. Legless lizards, which can also be seen on the roads at night, look like small snakes, but have an external ear opening and are able to regenerate their tail if they lose it.
Frill-necked lizards are the largest and most spectacular of the dragons: they emerge at the onset of the wet season after spending most of the cooler months in the tree tops. Also common throughout the lowlands is Gilbert's dragon, often called the ta-ta lizard because of its habit of waving its front feet.
Prominent in the lowlands are the termite mounds. Inside each mound is an intricate network of tunnels and chambers that serve as highways to food and water, as areas for storing food, and as nurseries. Over 55 species of termites occur in the park, although not all of them build mounds. Some live in and on trees; some live completely underground. Wood-eating termites hollow out tree limbs and so provide homes for many other lowland birds, mammals, reptiles and amphibians.
The greater part of Kakadu is covered by eucalypt-dominated open forest and woodland. These tracts are among the last expanses of virgin eucalypt forest in Australia. The lowland plants are heavily influenced by seasonal factors. The wet season is a period of growth, when plants make the most of the abundant water. The dry season is a more stressful time, and the plants have a variety of mechanisms for coping with this long waterless period. Some, such as the kapok bush, are deciduous. Others, such as the green plum, are semi-deciduous and have a waxy film on their leaves to help reduce water loss. Eucalypts generally have a deep root system, enabling them to reach the available ground water.
Open forest is dominated by the Darwin stringybark, Darwin woollybutt and Cooktown ironwood. Late in the dry season the Cooktown ironwood, with its dark, chunky bark and lime-green leaves, stands out from the surrounding vegetation. Woodlands contain many types of eucalypts, including bloodwoods and boxes. The understorey of both open forest and woodland is generally made up of smaller trees such as pandanus and green plums, shrubs, and tall grasses such as spear grass. The greatest species diversity occurs, however, in the ground layer, where there is a large range of grasses, sedges and wildflowers.
Kapok bush | Photo: Sally Greenaway
- Billy goat plum Terminalia ferdinandiana An-morlak
Harvested commercially outside of Kakadu and marketed as the Kakadu plum. It is a medium-sized tree with large broad leaves. It is deciduous in the dry season and between March and June and bears edible fruits known to have exceptionally high levels of vitamin C.
- Cooktown ironwood Erythrophleum chlorostchys An-dubang
A tall, spreading tree with distinctive rounded dark-green leaves. Late in the dry season it puts out new leaves that are a bright lime-green. The tree's timber is extremely hard and termite resistant. All parts of the tree are highly poisonous to mammals.
- Darwin woollybutt Eucalyptus miniata An-djalen
Grows to 10-20 metres; it has dark, rough bark on the lower half of its trunk and smooth, white bark on the upper half. Bright-orange flowers appear between May and August.
- Fern-leafed grevillea Grevillea pteridifolia An-dadjek
A medium-sized slender tree with long, narrow silver foliage. The flowers are bright orange and appear from May to August. The nectar from the flowers attracts many birds.
- Green plum Buchanania obovata An-dudjmi
A medium-sized tree with large, thick leathery leaves. Bunches of green grape-sized plums appear in October to December; they are considered to be some of the best bush tucker around.
- Kapok bush Cochloprerum fraseri An-djedj
Deciduous in the dry season, from May to August, and has distinctive bright-yellow flowers. Its large, fragile pods are filled with a dense, soft cotton-like material.
- Red-flowered kurrajong Brachychiton paradoxum An-marrenarnak
A small, often straggly tree that is widespread on the lowlands. It is deciduous in the dry season, when bright-red bell-shaped flowers appear on short stems from the branches.
- Sand palm Livistonia humilis An-gulalurrudj
A slender fan palm with small yellow flowers on long spikes. Aboriginal people use it for medicines, fibre, dye and food.
- Spear grass Sorghum spp. An-ngulubu
Grows to over two metres and becomes the dominant understorey plant towards the end of the wet season.
- Spiral pandanus Pandanus spiralis An-yakngarra
Grows in a broad range of habitats, often in dense stands. Aboriginal people use it for medicines, fibre and food.
- Swamp banksia Banksia dentata Guibuk
The only banksia found in the Top End. It has distinctive serrated leaves and the characteristic banksia flower, which appears between January and April.
- Turkey bush Calytrix exstipulata Anbarndarr
Common throughout the lowlands. It bears masses of pink-purple flowers between May and August.