As the camera was being fixed, a different call from the mother caused the young one to run away. Three or four naturalists tried to catch the active little bird, which stopped for a moment and disgorged two whole small fish, with which its mother had evidently but recently fed it. Eventually a good picture was obtained. These Terns nest singly, though others nest in large companies. They obtain fish by diving into the sea. It was interesting, on a Nature-study excursion, to watch the Crested Terns diving frequently into the sea above a shoal of small fish at Sandringham.
We found the Noddies breeding in thousands on Mast Head Island, in the Capricorn Group. They built a small platform of leaves, or seaweed, high or low, on every possible nesting site on the great Pisonia trees. In fact, there is an interesting kind of partnership between the bird and the tree. The fruits of the Pisonia have bands of sticky glands, which adhere to the plumage of the birds. After a time the fruits fall off, possibly on another island, and so this interesting tree is spread throughout these small coral sandbanks and islets. The birds are sometimes so loaded and clogged with these fruits that they are incapable of flight. Surely here is a wonderful partnership between the tree-frequenting Noddy and the forest tree that provides shelter and nesting places for it. It is, indeed, a marvellous method of seed dispersal.
The number of ocean birds breeding on these tiny island-paradises is amazing. Minute Mast Head Island is a place free of all pests—no flies, no mosquitoes, no ticks, no snakes, nor prickly plants, but a deep shady forest of giant Pisonia trees, sometimes covered with creepers and lianas, and fringed with pretty flowering shrubs, fig trees, and long green grass, and surrounded, above spring-tide level, by a fringe of graceful Horse-tail Sheoaks (Casuarinas). We calculated that over 100,000 birds bred annually on this 100-acre sandbank, no point of which rose 10 feet above spring-tide level. The graceful White-capped Noddies already mentioned nested high and low on the trees and shrubs. Petrels in thousands burrowed in the sand under the giant Pisonias, which are so thickly foliaged that not enough light penetrates to enable undergrowth to flourish, so the sand was practically bare in the centre of the island. Reef Herons nested low on spreading branches or interlacing roots. Silver Gulls and Oyster-catchers nested on the ground, within about a yard of the spring-tide mark; Doves, Silver-eyes, Bell-Magpies (Streperas), Caterpillar-eaters, Kingfishers, and other land birds nested in the trees, while the White-bellied Sea-Eagle (almost a fac-simile of the Bald Eagle of America) had his nest overlooking all, on the highest tree on the island. The Frigate Birds were not nesting on Mast Head Island, but they roosted each night in the tall Sheoaks at the water's edge. It was a treat, in the late afternoon, to see these glorious birds winding up their invisible staircase into the vast void of upper air. Gloriously and calmly they sailed up and up, until the merest speck only could be seen. Of corals, turtles, and other marvels we may not speak here. The migrating wading-birds had just reached the island after their long journey from Siberian Tundras. Some were so poor that we caught Sandpipers by hand. Flocks of Turnstone, Golden Plover, Godwits, Curlew, and other wading-birds were there, possibly only resting before continuing their journey to the South. It was indeed a privilege to live on such a spot for nine days and to see Nature in some of her most interesting phases.
The two Australian Seagulls illustrate the "law of representatives" so often referred to by Gould. It is strange how often a closely similar representative of a Northern bird is found in Australia. Thus the big Pacific Gull is the representative of the large Gull of Europe, though its peculiar deepened and orange-colored bill is distinctive. It does not gain its beautiful white and black plumage until it is three or more years old, being brown in the first year, and brown and white in the second year.
The Silver Gull is known to all. Though a dainty-looking bird, it has a bad character. It is worse than any bird of prey for stealing eggs and young birds, for let a gannet or other nesting bird but leave the nest for a moment, and Gulls quickly rob it of its contents. They are scavengers, and eagerly follow a steamer at lunch-time to gather the scraps. An interesting sight of Currie Harbor, King Island, is to see the large company of Seagulls nesting undisturbed on a tiny, bare, rocky islet close to the pier.
It was noted that, whenever the Noddies were disturbed, and rose, protesting loudly, the Gulls immediately gathered and hovered over the trees containing Noddies' nests. Evidently they were looking for unprotected eggs.
Placed in the next family are the seven robber Gulls or sea pirates—Skuas. We read of these birds in the old Royal Readers, but few recognized them when they followed us to the Summer School of 1910. They also followed our afternoon-tea cruise to South Channel fort, and played their usual game of compelling the Seagulls to give up the scraps they had gathered. The Robber Gull, or Skua, of Victoria is, strange to say, identical with the Skua of England. The one that followed the s.s. Lady Loch to the Summer School is better known in England as the Arctic Gull or Richardson Skua. It breeds in the far North, so it is a great traveller.
One interesting fact about these birds is that they show two sets of plumage. Thus, while each bird, as it gets older, usually changes its immature and almost uniform dusky plumage for a white under-surface, an incomplete white collar, and a blackish cap, yet some retain the dusky plumage throughout life. This is a good example of "dimorphism," as it is termed. Usually, instead of picking up their own prey, they watch until some other bird has captured a meal, and then they rapidly pursue it and cause it to disgorge. They do not skim over the waves like Petrels, but show a heavy, labored flight, varied by a short soar. As the two centre tail feathers project beyond the rest, the birds can be readily identified as they follow a steamer for tit-bits.
