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VOL. 8 (6) JUNE, 1980 171 Birds of Victoria River Downs Station and of Y arralin, Northern Territory Part 1 By CON BOEKEL, Ngukurra, Roper River, via Darwin, Northern Territory, 5791. Introduction Knowledge of the avifauna of the area surrounding the confluence of the Wickham and Victoria Rivers, Northern Territory, is particularly sketchy. This paper presents data covering the occurrence, habitats, breeding, movements and behaviour of birds recorded between February 1975 and December 1977. Study Area Observations were made in an area bounded by Lesson Creek in the Fitzgerald Range, thence east across the Victoria River to Middle Creek, south along the valley of the Victoria to the region of Pompey Knob, west of there along the hills and valley of the Wickham River to its confluence with Deep Creek, thence north-easterly to Crawford Springs, finally crossing the Fitzgerald Range to the headwaters of Lesson Creek. Method A monthly checklist was kept during 1976-1977. Somewhat irregular counts were made of waterfowl and waders at the various billabongs. A checklist of habitats and breeding species was also kept. Once a bird had been positively recorded as breeding attention was switched to those species for which breeding was yet to be recorded. Almost the whole of the study area was covered on foot. Observer coverage was good in The Dry but suffered due to inaccessibility in The Wet. Climate The climate is monsoonal with a long warm dry season (The Dry) between April and October, and a hot rainy season from November to March (The Wet). Rainfall is mostly from thunderstorms associated with the northwest monsoon; the annual average ranges from 600 mm in the northwest to about 500 mm in the southwest. At Victoria River Downs Homestead the daily average maximum and minimum for the coolest month, July, are 27.3°C and 8.8°C, respectively. The average daily maximum exceeds 37.8°C from October to February. The highest average maximum occurs in February, 40.7°C, when the average mini·­ mum is 26°C. Although frost occurred at Pigeonhole and Mount Sand­ ford to the south of the study area, none was recorded during the study period. Habitats Riverine Canopy: This habitat i~ of variable consistency and density. It is most dense where Leichardt Pines and fig trees form associated stands. It is least dense where the rivers are fringed by paperbarks, coolabahs and river gums. The composition of the canopy affects the composition of the avifauna. Riverine Understorey: Also ranges from straggly assortments of bushes to dense stands of Pandanus aquaticus, sapling paperbarks and compact bushes. AUSTRALIAN 172 BOEKEL BIRD WATCHER Coolabahs: Form extended stands along some stretches of the major rivers and billabongs in particular. Savanna Woodland: Extends from the riverbanks to the foot of the scarps. Included here are all associations of trees with the exception of spinifex woodland. Extremes range from a rather rocky limestone association of limestone, grass and rather sparse stunted trees, to rank 1-1! m grass and taller trees. Spinifex Woodland: Is found on the slopes and plateaux which ring the study area. No birds which are specific to spinifex habitats are found in the study area. Shrub Thicket: Some shrubs in isolated areas have formed into dense thickets. In general they lack a diversity of species. Ficus Thicket: Most of the plateaux are edged with cliffs of varying height. Ficus thickets are found in these places. They are generally of stunted trees, often associated with a very poor form of monsoon scrub characterised by vines and the absence of a ground layer of grasses. Grassy Plain: Characterised by black soil, these consist of grasses growing 1-2 m high. Large areas of these are inundated to a shallow depth during The Wet. They are heavily grazed by cattle so that by the end of The Dry they are either covered with short grass or are bare. Shrub Grassland: Is intermediate between savanna woodland and grassy plain. Usually it is formed of dense tangles of mixed grass, small shrubs and herbs. Usually found on, or bordering, depressions and hollows. Deep Creek area: Where Deep Creek flows into the Wickham River there is a concentration of cliffs and old watercourses which has led to an unusually lush growth of riverine vegetation and savanna woodland. Aquatic: This includes many ephemeral streams and pools, deep permanent holes in the two major rivers, permanent billabongs (Mauka and Crocodile) and ephemeral billabongs (Racecourse). Human Factors Influencing Environment Two cultures and hence economies affect the area. The original culture was that of the Ngarinman tribe, which persists in modified form. Firing was practised and it is assumed that this has had similar effects in the study area to that described elsewhere. Most species of bird were regarded as food, whether birds were adult, nestling or egg. Many of the larger species, mainly waterfowl and the Australian Bustard, are still keenly hunted albeit with rifle and shotgun. The feathers or raptors, in particular those of the Black Kite, are still used for ceremonial purposes. Previously eagle traps were constructed of rocks and saplings covered with spinifex grass. Fires were lit nearby and a small bird was twirled on the end of a string by a hunter who was concealed inside a hide. R aptors attracted by the fires would be caught when they attempted to take the bait. This was apparently very successful and an old man described to me how as a boy he had accompanied his father in such a hide. They had to stop midway through the operation because the number of dead raptors stopped movement inside the hide. These traps are located mainly on the edges of escarpments and are very common in some areas. Habitat modification now is limited to the collection of firewood and the chopping down of trees for the sugarbag (wild bee hives) they contain and also as raw material for the manufacture of boomerangs and spears. The second culture has had substantial impact since about the 1870's VOL. 8 (6) JUNE, 1980 Birds of Victoria River Downs 173 when the pastoral industry was established. The effect of European culture is difficult to measure because there are few early records of conditions pertaining at the onset. However, there is considerable evidence of environmental degradation. Erosion is widespread on the riverbanks. Introduced species such as Parkinsonia arcuata, Rubberbush, and a wide variety of burrs and prickles are widespread and completely dominate some areas, particularly along the riverbanks and watercourses. Bunch Spear Grass also dominates some areas, Feral cats and donkeys are abundant. An estimated 150,000 cattle are run on an area of just under 5,000 square miles. Approximately half of these are out of control by virtue of their being able to escape helicopter muster in rough country or in well-treed riverbank areas. Attempts to fence off the river frontage have been frustrated by floods and the depressed state of the cattle industry. Some birds are kept as pets. Some waterfowl are hunted. Raptors including Black-breasted Buzzards, Black Kites and Wedge-tail Eagles are shot. 15/ 0 3/J 1217" "' l-:. ';: ~ -- ~ ~..,.4 -- .. •' -;,,\ "it,, fl\,-: - _..,.....( River HU ~~~~~~~~~~~~~~~+-~~~----_S~----~~~----~~~ I I /. r r}' It 1/ (& . I --~(' ) Map of Study Area, Victoria River Downs. AUSTRALIAN 174 BOEKEL BIRD WATCHER Species List Emu Parties of less than ten birds, sometimes with young, were occasionally reported. Apparently more common formerly. The Ngarinman have a substantial body of lore relating to the habits of emus and how best to hunt them. Reports indicate that emus occupy areas remote from river valleys during The Wet and approach these in The Dry. Even so, they appear to avoid better-grassed areas and stay on local rises with sparser vegetation. Australasian Grebe Are present throughout the year on all larger billabongs. On Crocodile Billabong they avoid deep open areas, apparently fearing the Freshwater Crocodile Crocodylus johnstoni. They are concentrated on Racecourse Billabong, with up to twelve birds, while other billabongs generally carry but ones and twos. Breeding: Two adults with four small young at Race­ course Billabong on March 28, 1976; an adult with two large young on an unnamed billabong a short distance east of the station homestead on May 12, 1976. Absent from even the largest of river pools and from minor streams. Australian Pelican Flocks generally numbered between twenty and fifty on billabongs between May and December, with isolated occurrences in other months. Presumably moves off to breeding grounds in the intervening months. Birds use the "elbow" of the wings to scratch the otherwise inaccessible portions of the head. This bird suffers above all from indiscriminate shooting by both Ngarinman and Europeans. Observations at Wycliffe Swamp indicate that this may well be a Territory-wide practice. Law enforcement is not possible owing to the sparse population distributed in often inaccessible areas. The only way to protect wildlife in the Northern Territory is through proper education and social pressure. Thus attempts from "Down South" to improve the situation are likely to be met with hostility from those sections of the community which indulge in indis­ criminate killing. Darter Throughout the year but does not breed locally. It is common along major rivers and billabongs, but rare in pools along smaller streams. Numbers low in the period January to May but increase as breeding birds and immatures return. Darters do not flock locally but maintain an even distribution in a given length of river or billabong. When disturbed they can soar to great heights and can be seen to fly over long distances of sandstone and spinifex habitats. Great Cormorant Rare non-breeding visitor (see Boeke!, 1978).

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