Wetland Habitats 1: Wetland Habitats of the Top End
WETLANDS HABITATS 1: Wetland Habitats of the Top End
|Wetland Habitats of the Top End (M. Michie after NTDE, 1994)
|Main Rivers and Tributaries
|Billabongs and Lagoons
|Woodlands and Open Forests
|Sandstone Monsoon Forests
It is generally accepted that Indigenous Australians first arrived in Australia 60,000 years ago. It is possible that it could have been earlier than that, but there is positive archaeological evidence that people have lived in the Top End for at least 25,000 years. At that time the region was much drier, more sparsely vegetated and relatively cool. The world was in the grip of a great ice age and much of the Earth's water was frozen at the poles. The sea was some 350 km further north and Australia was joined to New Guinea. At the end of the ice age world temperatures began to warm up, the ice gradually melted and sea levels began to rise. Increased rainfall from about 10,000 years ago caused the growth of forests and woodlands, which remain much the same today, and also caused the spread of pockets of rainforest.
As sea levels rose the present river valleys were flooded. The floodplains gradually silted up leading to the development of mangrove swamps about 7,000 years ago. Within the last 1,500 years siltation and the levee formation (high riverbanks) restricted the intrusion of salt-water tides and allowed the formation of the present freshwater swamps and floodplains that are filled up each year. The floodplain landscape is a comparatively young one, and it is still evolving.
Mangroves are usually associated with estuaries and other coastal landforms, but in the Top End they also line the riverbanks of the tidal rivers for a distance of up to 50 km from the mouth of the rivers. The largest mangrove communities of the region are in Darwin harbour and the estuaries of the Adelaide and West Alligator Rivers.
|Mangroves (Ian Morris)
The mangrove lined estuaries are interesting habitats because they form a transition zone between the coastal marine areas and the freshwater rivers that empty into them. Because of the large tidal ranges of the mangrove regions, fishes in the mangrove habitat could be expected to be tolerant of both salt and fresh water. Some fish species such as the Barramundi (Lates calcarifer) and the Oxeye Herring (Megalops cyprinoides) spawn around the river mouth and their young develop in coastal swamps. When ready, juveniles move into the mangrove estuaries and migrate upstream. At 3-4 years of age they migrate back to salt water to breed. It is about this age when male Barramundi reach 75 to 80cm, and they change into females.
Other fish species of the mangroves are Mangrove Jacks (Lutjanus argentimaculatus), a medium sized predator of other fishes, the Estuary or Brown Stingray () and the Common Hardyhead (), a small fish that forms dense schools. There are about 10 species of mudskippers in the Northern Territory and the most commonly seen are the mudskippers from the genus Periophthalmus that grow to 50-100 mm in length.
Fiddler Crabs (Uca flammula) grow to a width of up to 35 mm and the males are equipped with one large colourful claw for mating displays. They live in the intertidal zone, eating algae from roots, stones, decaying leaves or the detritus of the estuary. They are tolerant of a large range of salinities. Mangrove, land or marsh crabs (), are a larger species up to 40 mm in width. They are responsible for most of the burrows seen along the high tide mark in mangrove forests and are scavengers and predators. The large Mud Crab (Scylla serrata), whuch grown up to 200 mm wide, is fished commercially and lives on the muddy banks or bottoms of mangrove estuaries.
Young Banana Prawns () drift into mangrove estuaries from the coastal spawning grounds while they are in a larval stage. They develop into juveniles and remain for a time in the safety of the mangroves. Two or three months after arriving, usually in the wet season, they then migrate into deeper waters offshore. Without the mangrove and seagrass nurseries there would be no prawns and no prawning industry; a fact that is often overlooked by planners and developers.
Mangrove habitats support a number of bird species, such as the Mangrove Golden Whistler (Pachycephala melanura), the Mangrove Robin (Eopsaltria pulverulenta), the Collared Kingfisher (Todiramphus (Halcyon) chloris) and the Red-headed Honeyeater (Myzomela erythrocephala). Striated Herons (Ardeola striata) and Eastern Reef Egrets (Ardea sacra) also breed in the mangrove forests. Brahminy kites (Milvus indus), White-bellied Sea-eagles (Haliaeetus leucogaster) and Osprey (Pandion haliaetus) are often seen circling over estuaries searching for prey.
Large reptiles can also be found living in the mangroves. These include the highly patterned Mangrove Monitor (Varanus indicus), the crab-eating White-bellied Mangrove Snake (Fordonia leucobalia), the Bockadam (Cerberus rynchops), another snake found in the mangroves, and the Saltwater, or Estuarine Crocodile (Crocodylus porosus).
The little-known, and rare, False Water Rat (Xeromys myoides) nests in clay mounds near the base of mangrove trees and eats crabs. Black Flying-foxes (Pteropus alecto) also favour mangroves and islands in the estuaries of large rivers as safe camps, and thousands can be seen at nightfall flying towards their feeding grounds.
Main Rivers and Tributaries
The rivers are the lifeblood of the wetlands system. They determine the physical structure and terrain of the region and shape the land so that numerous habitats are formed which in turn support the rich variety of wetland wildlife. Sand and silt are the building materials of the rivers. The heavy monsoonal rains of the wet season are responsible for transporting and dumping these materials resulting in the gradual building up of the floodplains and river levee banks.
|Wangi Falls, Litchfield National Park (Michael Michie)
The rivers of the region, the Adelaide, Mary, Wildman, West Alligator, South Alligator and East Alligator Rivers are at various stages of development. The Adelaide River follows a clearly defined course after it emerges from the woodlands onto the flood plain and then it follows a sinuous path to the sea. The South Alligator River's upper reaches do not connect directly with the tidal part of the river, but spread out at Yellow Waters into a broad basin which is drained by multiple unconnected channels to form the main river once again. The Mary River is a clearly defined stream where it is crossed by the Arnhem Highway, but soon spills out onto a black soil plain where it divides into a series of channels and connected billabongs, some of which are the remains of an older river bed. The river itself does not reach the sea but in the wet season empties out onto coastal swamps that drain into the sea via a number of small creeks.
The physical structure of the rivers, along with the seasonal cycles of the region create a set of environmental conditions which affect the lives of all the wetlands organisms. Because each year is different in terms of the amount of rainfall, the time of its arrival, the length of the wet season and the intensity of storms, wildlife of the Top End wetlands needs to be above all, adaptable.
Large Silver-leafed Paperbarks (Melaleuca argentea) are the most common tree in many stretches of the main rivers and their sheer size and grandeur dominate the riverbank scene. Besides the trees previously noted from riparian habitats, other trees lining the banks may include the pine-like Leichhardt Tree (Nauclea orientalis) and the Red-flowering Bombax Tree (Bombax ceiba).
Birds often associated with the riverbank vegetation are the Red-tailed Black-cockatoo (Calyptorhynchus magnificus), the Varied Lorikeet (Psitteuteles versicolor), the Spangled Drongo (Dicrurus bracteatus) and the White-throated Honeyeater (Melithreptus albogularis). Australian Pelicans (Pelecanus conspicillatus) congregate on the quiet reaches of major streams. Little Black Cormorants (Phalacrocorax sulcirostris), White-bellied Sea-eagles (Haliaeetus leucogaster), Darters (Anhinga melanogaster) and Little Pied Cormorants (Phalacrocorax melanoleucos) are also common along the rivers.
Mammals such as Sugar Gliders (Petaurus breviceps) and Northern Brushtail Possums (Trichopsurus arnhemensis) are also common in the woodlands, and use the trees of the riverbanks for shelter.
Freshwater Crocodiles (Crocodylus jhonstoni) lays their eggs in river sandbars, where they are eagerly sought after by Goulds, or Sand, Monitors (Varanus gouldii). The Pig-nosed Turtle (Carettochelys insculpata) has been observed in the Daly River and the South and East Alligator Rivers. It eats fruit from Water Pandanus (Pandanus aquaticus), Bush Apples (Syzygium spp.) and Figtrees (Ficus racemosa) that drop into the water. Macleay's Water Snake (Enhydris polylepis) hides amongst exposed tree roots by river banks to ambush its prey – fish, eels and frogs.
Salmon Catfish () seek food on the beds of the rivers, eating anything that comes their way, while Longtoms (Strongylura krefftii) cruise the surface under overhanging vegetation looking for small fish or freshwater prawns. Barramundi (Lates calcarifer), Sleepy Cod (Oxyeleotris lineolata) and Butler's Grunter (Syncomistes butleri) are other river dwellers.
After flowing down the creeks through the rolling woodlands, the rivers emerge onto expansive floodplains. The channels across the floodplains are not necessarily continuous, and the floodplains act like a huge retarding basin, storing the water up over the wet season and gradually releasing it. The waters drain back into the main channel that completes the journey to the sea with levee banks on either side.
|Magela Floodplain (Ian Morris)
The floodplains are built on three levels. The high land closest to the river forms the grasslands that may only flood to a depth of 3 cm, or in some seasons not at all. This is where the Paspalum (Paspalum scrobiculatum), couch (Elymus repens) (non-native) and millet (Panicum trichoides) grow. Solitary clumps of Pandanus (Pandanus spiralis) are the only trees on the grass plains.
Beyond the grass plains are the sedgelands, the typical wet season swamps covered with sedges, rushes, wild rice, waterlilies and other aquatic plants. The sedgelands appear complex because of the many channels criss-crossing the habitat to connect deeper lagoons and ponds. The water in the sedgeland floods to a depth of about 75 cm.
The lower plains are the first to flood in the wet and the last to dry out when the dry season arrives. These are the paperbark swamps and they may be flooded to a depth of 1 m. They adjoin the woodlands that border the floodplains, and obtain water from small creeks and local surface runoff. They are a place of refuge and haven for many of the wetland animals.
Not all of these parts of the floodplains are necessarily found in the one place. Often one type of floodplain vegetation blends in gradually with the other, the type of vegetation depending on the seasonal conditions.
Animals of the wet season: Fishes that appear in the shallow waters include Spangled Grunters (Leiopotherapon unicolor), Chequered Rainbowfish (Melanotaenia splendida inornata) and Reticulated Glassfish (Ambassis macleayi). Large numbers of damselfly and dragonfly nymphs appear along with other aquatic insects providing food for Radjah Shelducks (Tadorna radjah). Other ducks appear in great numbers: Plumed Whistling Ducks (Dendrocygna eytoni), Wandering Whistling Ducks (Dendrocygna arcuata) and Pacific Black Ducks (Anas superciliosa). Four species of egret (Ardea ibis, A. alba, A. intermedia and A. garzetta) are found on the floodplains, plus Glossy Ibis (Plegadis falcinellus), Brolgas (Grus rubicundus), Black-necked Storks, or Jabiru (Ephippiorhynchus asiaticus), Comb-crested Jacana (Irediparra gallinacea) and Magpie Geese (Anseranas semipalmata) gather for the abundant food provided by the wet season and many birds breed at this time of the year. The Magpie Goose in particular has its whole life style and breeding cycle tied into the seasonal changes of the floodplains. About 25 species of waders of the sandpiper and plover families also use the floodplains as a migratory stopover.
Arafura File Snakes (Acrochordus arafurae), confined to permanent billabongs for the dry (one scientist captured, marked and released more than 2000 filesnakes from Dja Dja billabong) spread out across the floodplains in the wet season along with Olive Pythons (Liasis olivaceus (Bothrochilus)) and Water Pythons (Liasis fuscus (Bothrochilus)).
Animals of the dry season: Water Pythons and Dusky Rats (Rattus colletti) are the main inhabitants of the floodplains in the dry season, but other animals, such as Dingoes (Canis lupus dingo) and Barn Owls (Tyto alba), may also be active in what appears to be a lifeless habitat.
Ground-dwelling birds such as the Brown Quail (Coturnix australis), Masked Lapwing (Vanellus miles), Richard's Pipit (Anthus novaeseelandiae) and Australian Pratincole (Stiltia isabella) find sufficient food, like fallen grass seeds, new growth after fires, and insects, to exist through the dry season. Black Kites (Milvus migrans) swarm around the fires that sweep through the grasslands in the dry season, catching insects and lizards disturbed by the approaching flames. The Marble-headed Whip Snake (Demansia olivacea) hunts for skinks in the clumps of grass, and the Black-headed Python (Aspidites melanocephalus) searches for small mammals and birds in crevices and cracks in the soil. The Yellow-spotted Monitor (Varanus panoptes) usually chooses higher ground on the floodplain to dig its burrow.
Four species of Melaleuca form the paperbark forests. Two, the Cajaput Tree (Melaleuca cajuputi) and the White Paperbark (Melaleuca leucadendra), occur in areas that are flooded for up to eight months whilst the other two species Melaleuca nervosa and the Broad-leaved Paperbark (Melaleuca viridiflora) are found in swamps flooded for only a short time. All paperbarks are prolific flower producers and attract large numbers of insects and nectar feeding birds when in flower.
|Paperbarks Swamp, Indian Head Island (Ian Morris)
Fish species that are common in many wetlands habitats in the wet season may also be found in the paperbark swamps, for example, the Black-banded Rainbowfish (Melanotaenia nigrans) and the Banded Grunter (Amniataba percoides). Reptiles of the paperbark swamps include the Swampland Lashtail (Lophognathus temporalis) and Mitchell's Water Monitor (Varanus mitchelli), which is often seen on partly submerged trees. The Swampland Lashtail's main diet is insects, especially Green Ants (Oecophylla smaragdina). It is inactive in the dry season, hiding under fallen timber or the paperbark roots where other animals such as water rats may also shelter.
Dahl's Aquatic Frog (Litoria dahlii) floats in the water with its legs outstretched to prey on insects and other frogs. Males of the large Green Tree Frog (Litoria caerulea) call from the ground during the breeding season and high in trees at other times. The Roth's Tree Frog (Litoria rothii) requires deep pools for breeding.
The Little Red Flying-fox (Pteropus scapulatus) congregates in vast numbers to use the paperbarks as a resting place during the day. Little Broad-nosed Bats (Scotorepens greyii) also roosts in tree hollows in the paperbarks. The Large-footed Mouse-eared Bat (Myotis adversus) forms colonies of 10-15 in dense foliage on the wetlands, and hunts by raking the surface of the water with its claws as it flies low over swamps and rivers.
Radjah Shelducks (Tadorna radjah), Pacific Black Ducks (Anas superciliosa), Australasian Grebes (Podiceps ruficollis) and pairs of Green Pygmy Geese (Nettapus pulchellus) will be often seen feeding in the paperbark swamps and the Lemon-bellied Flycatcher (Microeca flavigaster) is also common in this habitat. Forest Kingfishers (Todiramphus (Halcyon) macleayii) favour this habitat and often use arboreal termite nests in trees as a nesting place of their own. The distinctive call of the Whistling Kite (Milvus sphenurus) is a common sound to be heard as it patrols the treeline at the edge of the paperbark swamps.
Billabongs and Lagoons
These water bodies may be conveniently grouped as;
- older sections of the rivers are cut off from the main channels through the buildup of sediments on river bends and become permanent waterholes of the floodplains
- lagoons may form when surface runoff gathers in a very low-lying part of the terrain
- before reaching the rivers, tributary creeks in the upper catchment area may become eroded, widened and deepened, so that sometimes in the dry season a watercourse may be a string of waterholes or billabongs joined by a sandy creek bed.
|Billabong, Mirrngatja area (Ian Morris)
Billabongs generally only flow in the wet season, and perhaps early dry season, when water levels are high. At these times the water still flows at a slower rate than in the main rivers and creeks, and not at all in the late dry. These slow flowing or still waters are an advantage for most of the aquatic creatures, allowing them to feed and breed without having to cope with fast currents. However, when water stops flowing in the dry season and levels in the billabongs drop, organisms are gradually placed under stress because of higher temperatures and reduced oxygen levels in the water.
Fish such as the omnivorous Banded Grunter (Amniataba percoides) have evolved in Northern Territory drainage systems and are tolerant of a wide range of conditions. The Sooty Grunter (Hephaestus fuliginosus) prefers billabongs with sandy bottoms in the upper reaches of the rivers and creeks. It is an important dispersal agent for Water Pandanus (Pandanus aquaticus) seeds. The Sailfin Glassfish (Ambassis agrammis), Empire Gudgeon (Hypseleotris compressa), Mouth Almighty (Glossamia aprion) and Rendahl's Catfish (Porochilus rendahli) are other residents of the billabongs. Redclaw Yabbies (Cherax quadricarinatus) live in waterholes with abundant vegetation and are detrivores, obtaining organic matter from silt and mud. The Water Rat (Hydromys chrysogaster) digs a tunnel for shelter besides a waterhole and feeds on freshwater snails, mussels, yabbies, fish and large insects.
Rainbow Bee-eaters (Merops ornatus) also make their nests in tunnels in the banks of billabongs, as well as the banks of other watercourses, and Purple Swamphens (Porphyrio porphyrio) hide in the sedges at the water's edge. The widely distributed White-faced Heron (Ardea novaehollandiae) and the smaller Pied Heron (Ardea picata) hunt in shallow water around lagoons and swamps. The Azure Kingfisher (Alcedo azurea) and Little Kingfisher (Alcedo pusilla) are two small kingfishers of the billabongs: other birds also include the Blue-faced Honeyeater (Entomyzom cyanotis) and Dollarbird (Eurystomus orientalis).
Macleay's Water Snake (Enhydris polylepis), File Snakes (Acrochordus arafurae), Keelbacks (Tropidonophis (Amphiesma) mairii), both Freshwater (Crocodylus johnstoni) and Satlwater Crocodiles (Crocodylus porosus) and Olive Pythons (Liasis olivaceus (Bothrochilus)) occur in this habitat, each having its own preferences and strategies for hunting prey. Gilbert's Lashtail Lizard (Gowidon (Loghognathus) gilberti) perches on branches or termite mounds near waterholes, feeding on insects and smaller lizards. The Northern Snake-necked Turtle (Chelodina rugosa) and the Northern Snapping Turtle (Elseya dentata) inhabit not only rivers, but permanent lagoons and billabongs as well as.
What is not obvious in the billabongs is the huge population of microscopic plants and animals, termed plankton, that support the larger species of the permanent waterholes. Microcrustaceans, rotifers and amoebae are some of the zooplankton that provide an energy source for small aquatic insect, which in turn are the basis of the food web. It would be difficult to exaggerate the incredible diversity and ecological value of the microscopic freshwater life of the wetlands.
Woodlands and Open Forests
Woodlands have a 10-30% foliage cover, compared to 30-70% for open forests. In the Top End the two merge into each other with different species of eucalypts being dominant in the different communities. For the purpose of our habitat overview, the term woodlands will be used. Broadly speaking, it is the type of vegetation that surrounds Darwin and lines most of the Arnhem Highway.
|Woodland & Open Forest, Litchfield National Park (Ian Morris)
The woodlands provide the setting for the Top End wetlands. The upper reaches of the rivers flow through woodlands after leaving the hills and escarpments, and woodlands form a corridor in which the longer rivers and their floodplains lie. Animals of the woodlands may use the adjoining floodplains as a resource for food, whilst the woodlands provide a place of refuge for some animals of the floodplains when the wet season arrives.
Although not giving the appearance of being a species rich habitat, the tropical woodlands in fact support a variety of plant species and associated wildlife, more diverse than the floodplains. In this habitat there are sixty-four species of mammals, over one quarter of Australia's total number. Most of the carnivorous mammals are nocturnal, including the Brush-tailed Phascogale (Phasfogale tapoatafa), the Red-cheeked Dunnart (Sminthopsis virginiae), and the Northern Quoll (Dasyurus hallucatus). However, the most common of nocturnal carnivores is the Fawn Antechinus (Antechinus bellus). The Northern Brown Bandicoot (Isoodon macrourus) is also nocturnal, but omnivorous, eating seeds, berries, plant roots, spiders and earthworms. Some herbivorous residents of the woodlands include the Antilopine Wallaroo (Macropus antiloponus), Agile Wallaby (Macropus agilis) and Common Wallaroo, or Euro (Macropus robustus). Bats are the largest group of mammals found in the woodlands, some flying-foxes being important pollinators of eucalypts and paperbarks. Most of the other bat species, however, are insectiverous, except from the Large-footed Mouse-eared Bat (Myotis adversus), which feeds on fish. There are also fourteen species of rodent found in the woodlands, ranging from the large Black-footed Tree-rat (Mesembriomys gouldii) to the small Delicate Mouse (Pseudomys delicatulus). Dingoes (Canis lupus dingo) and Short-beaked Echidnas (Tachyglossus aculeatus) are also common in the woodlands.
The Brown Tree Snake (Boiga irregularis), Northern Death Adder (Acanthophis praelongus) and King Brown (Pseudechis australis) are some well known snakes of this habitat. The Lesser Black Whip Snake (Demansia atra) is perhaps not so well known and feeds on skinks, dragons and frogs. Frill-necked Lizards (Chlamydosaurus kingii) are the most popular and widely recognised reptile of the woodlands, whilst the smaller but equally common Northern Two-line Dragon (Diporiphora bilineata) remains relatively inconspicuous.
Birds in the woodlands are represented by the Blue-winged Kookaburra (Dacelo leachii), the Pied Butcherbird (Cracticus nigragularis), the Black-faced Cuckoo-shrike (Coracina novaehollandiae), Helmeted, Little and Silver-crowned Friarbirds (Philemon buceroides, P.citreogularis and P.argenticeps) and the Brown Honeyeater (Lichmera indistincta). The Barking Owl (Ninox connivens) and Southern Boobook Owl (Ninox boobok) are the most common of the nocturnal hunters. Besides the two species of lorikeets found in the Top End, the Red-collared Lorikeet (Trichoglossus rubritorquis) and the Varied Lorikeet (Psittruteles versicolour), three other parrots species also live in the woodlands: the Red-winged Parrot (Aprosmictus erythropterus), the Northern Rosella (Platycercus eximius) and the Hooded Parrot (Psephotus dissimilis).
At first acquaintance the tropical woodland seems typical of Australian bushlands in any state with its familiar mixture of eucalypts, wattles and a scattering of woody shrubs as an understorey. However, there are several features give that the Top End woodlands a distinctive tropical look and feel. Termite mounds, built by various species of termite, occur throughout the woodlands and there are a number of palms of the Cycas and Livistona species that add an exotic tropical touch to the landscape. A number of smaller trees form an understorey in the eucalyptus dominated community, which include species of Terminalia, Syzigium and Brachychiton. The first two genera provide bush fruit for the gatherers of the Northern Indigenous clans, as do two other smaller trees: the Cocky Apple (Planchonia careya) and the Green Plum Tree (Buchanania obovata).
There are small rocky hills and outcrops scattered over the woodlands terrain and these are the ultimate places of refuge when cyclone generated rains flood parts of the woodlands. Short-beaked Echidnas and Black Wallaroos (Macropus bernadus) are adapted to this particular habitat and various bat species use the caves for roosting places. The Children's Python (Liasis childreni (Bothrochilus)) takes advantage of this abundant supply of food and is often seen near the roosting sites. The endemic Chestnut-quilled Rock-pigeon (Petrophassa rufipennis) always shelters amongst rocks that are close to water. Copland's Rock Frog (Litoria coplandi) is common along rocky creeks and also lives in caves. The Masked Rock Frog (Litoria personata), which is similar in appearance, is also found here, though is rarely seen.
Monsoon forests of the Top End wetlands may occur in small patches where there is permanent water associated with springs and seepages. Trees in these evergreen forests include rotten cheesefruit or great morinda, a popular food plant of Northern Indigenous clans, native nutmeg and Macaranga species.
Most monsoon forests of the region are on well drained soils, and so dry out in the dry season. Some of the forests are quite small, but one patch on the Daly River is over 10 km long and 1 km wide in places. Other large tracts occur along the floodplain margins of the Adelaide, South Alligator and East Alligator Rivers. The most common species of tree of the lowland monsoon forests are the Black Wattle (Acacia auriculiformis), Milkwood (Alistonia actinophylla), Kapok Bush (Cochlospermum frazeri), Banyan Tree (Fiscus virens), and the Peanut Tree (Sterculia quadrifida). Many types of vines also grow in these forests including the Crab's Eye Vine (Abrus precatorius), Round Yams (Dioscoria bulbifera), Long Yams (Dioscoria transversa), Native Jasmine (Jasminum spp.), and Wild Passionfruit (Passiflora foetida).
|Berry Springs (Ian Morris)
The monsoon forests have a canopy that closes out much of the light, even though some of the trees are deciduous, and so there is little grass growing on the forest floor. There are many seedlings awaiting their chance when a gap in the canopy occurs, and a small number of ground orchids. In some locations ferns (Blechnum spp.) may also be common.
The monsoon forests are the stronghold of two Top End snakes; the Carpet Python (Morelia spilotes variegata), which preys upon rats, bandicoots, small wallabies, possums and fruit bats, and the smaller Common Tree Snake (Dendrelaphis punctulatus), which eats frogs, lizards and fish stranded in pools.
There are two interesting ground dwelling birds found in the monsoon forests - the Orange-footed Scrubfowl (Megapodius reinwardt), which is a mound builder, and the Rainbow Pitta (Pitta iris). The Dusky Honeyeater (Myzomela obscura), Shining Flycatcher (Myiagra alecto), Yellow Oriole (Oriolus flavocintus) and Figbird (Sphecotheres viridis) are common residents of the rainforests. Three species of pigeons feed upon fruit in the monsoon forests: the Rose-crowned Fruit-dove (Ptilinopus regina), the Torres Strait Imperial Pigeon, or Pied Imperial Pigeon (Ducula spilorrhoa), and the Bar-shouldered Dove (Geopelia humeralis). These birds, along with flying-foxes, are important agents of seed distribution in this habitat. Like the Imperial Pigeon, the Common Koel, or rainbird (Eudynamis scolopaceea), is a migrant from New Guinea for the wet season, during which time it breeds by laying eggs, as with most cuckoos, in other birds' nests.
The Grassland Melomys (Melomys burtoni) is a native rat that inhabits a range of coastal grassland habitats including isolated grassy patches within the rainforests where sunlight has penetrated.
Sandstone Monsoon Forests
Waterfalls plunge over the edge of the escarpment down deep incisions, into pools that are surrounded by dense sandstone monsoon forests. The waterfalls are spectacular during the wet season as they offload the rainfall on the elevated stone country. However as the dry season sets in, the waterfalls dry up, often to a trickle. Some of the falls, particularly in Litchfield National Park, continue to flow because of the large amount of water that is absorbed by the rocks themselves, and which trickles out of springs.
The dominant trees in the forests around these pools are Allosyncarpia ternata, as well as the Carpentaria Palm (Carpentaria acuminata). Many of the plants and animals are those found on the coastal monsoon forest, while freshwater fish, turtles and frogs can be found in the pools.
|Main Rivers and Tributaries
|Billabongs and Lagoons
|Woodlands and Open Forests
|Sandstone Monsoon Forests