58 NIELSEN, Birds of Lake [ Bird Watcher

Birds of Lake Bullawarra, south-west . Lying 17 miles west of in south-west Queensland, Lake Bullawarra, when full of water, supports many thousands of birds of a con­ siderable number of species. This lake lies in semi-desert country and is filled by the when it floods. The lake covers 20 square miles and is fringed with a species of a small eucalypt; these trees providing nesting places for the many birds which breed there periodically. Amongst the trees grow patches of lignum bushes, which are used by the Ibis as nesting places. On two sides of the lake the water spreads out into channels which intersect reed beds, where thousands of ducks and other species of birds, which prefer the seclusion of the reeds, reside. Sometimes, when the lake is full, there is a prolific breeding of aquatic life, especially a species of small fish which forms the main diet of the birds. With this food supply available the birds com­ mence to breed. From March until June 1956 the birds nested in countless thous­ ands. The colonies of Straw-necked Ibis and White Ibis coxered many acres of lignum bushes. The nesting of the Straw-ne~c~ed species does not appear to be common in Queensland. In addition to the nesting at Lake Bullawarra, I have records of a colony breeding at Toobeah, 40 miles west of Goondiwindi, in southern Queensland, in 1949. The Glossy Ibis is often seen in small numbers, but has not been recorded nesting. Other birds nesting included the four species of cormorants, Royal and Yellow-billed Spoonbills, three species of Egrets, Darter, . Grey Teal, Black Duck, Pink-eared Duck, Musk Duck, Freckled Duck, White-eyed Duck and Maned Goose. Whistling Eagles, Fork-tailed Kites and one pair of White­ breasted Sea-Eagles were breeding, while several other species of the birds of prey are often seen in the area but have not been known to breed. The Silver Gull is common and during April 1961 a flock of over 30 Gulls was seen on one small part of the lake. The Nankeen Night-Heron, which is common in the area, was found breeding in early 1961. The nests were situated low down in the lignum bushes, only a few inches above the water- a most unusual place for this species to nest. On a still evening the Brolgas can be heard near the lake as they peiiorm their dances. The Blue-winged Shoveller is often seen but I do not know if it nests in the area. Red-necked Avocets, 'Pacific Herons, Black-fronted and Red­ kneed Dotterels, Marsh Terns and Eastern Swamphens are common and breed freely. A colony of about 50 pairs of Crested Grebes nested successfully on a swamp some distance from the lake. December ] WHEELER, Pick-a-back Relationships 59 1963

A Whistling Eagle's nest, that contained a large young bird, had the remains of a young Straw-necked Ibis and pieces of rabbit skin and fur in it. It was near the lake that I heard the Fork-tailed Kite calling. The bird had been disturbed from its nest as I approached and it called at short intervals as it circled above. This is the only time 1 have heard this species call, which supports the claims that this Kite calls only while it is breeding. One of the interesting records is the breeding of the White­ breasted Sea-Eagle. This species has often been recorded from the inland but it is not usually found breeding so far from the coast. Lake Bullawarra is just over 600 miles in a direct line from the sea. This is a wonderful place for birds, especially the aquatic species, and the mass breeding of so many different birds is unusual. Lloyd Nielsen, Jandowae, Queensland, 8/ 1/1963.

Pick-a-back Relationships. The cheekiness of Willie Wagtails and Starlings riding on the backs of domestic animals happens too frequently to be of any significance. Whether this relationship with animals is purely accidental, or a necessity for food supply, or even an easy means for obtaining nesting material, has been the subject for comment on many occasions. However, during the last 18 months two other pick-a­ back relationships have been seen by me, which, even though commonplace overseas, have seldom been reported in Australia. The relationships between the Silver Gull ( Larus novae­ hollandiae) and the Australian Pelican (Pelecanus conspicillatus), and the Cattle Egret ( Ardeola ibis) and domestic animals, can be regarded as one of easy food supply. On two occasions, in recent months, the Gull/Pelican association was observed. The first occasion was at Moolap, near Geelong, on April 13, 1962. Sixteen Pelicans were feeding in a shallow salt-pan, probing their large bills forward and, with a backward sweep, disturbing and bringing to the surface masses of green slime. Much of this slime was eventually worked into their enormous bills and swallowed. Approximately 220 Silver Gulls hovered overhead and dozens were seen swimming close by, whilst several Gulls chose to ride on the backs of the feeding Pelicans. Some­ times at least five Gulls were simultaneously having rides, and on one occasion two Gulls shared the one host. The relationship appeared to be mutual, and the only act of annoyance shown by a Pelican occurred when a Gull landed on the top of its head. The other occasion when a similar behaviour was observed was near Beeac, just prior to sunset, on June 17, 1962. A large flock of over 400 Pelicans was grouped just off shore of the creeping lake area, and the birds were moving forward in a northerly direc­ tion, constantly fishing under water with their large beaks. On this occasion several hundred Silver Gulls were in attendance. Some of the Gulls were hovering overhead and frequently diving for