226 OCEANIC BIRD LIFE 



for brief moments. As a rule, they took no notice of the ship, though 

 occasionally the beautiful long-tailed white tropic-bird would follow us 

 for half an hour or so. Birds differ considerably in their reactions to a 

 ship. Some, such as the wandering albatrosses and pomarine skuas, will 

 follow one for days, others for only a short time; some will keep well 

 away from ships, scarcely coming within view; others again remain quite 

 unconcerned, only moving out of the way when the ship is almost on 

 top of them. These various reactions have nothing to do with their near 

 or distant relationship, and two closely related species will often react 

 quite differently. 



The relative abundance of bird life in the Banda Sea is explained by 

 the wealth of animal life in the surface water. This in turn is due to the 

 abundance of microscopic phytoplankton, which has exceptionally good 

 growth conditions because the outflow of many ri\'ers brings plentiful 

 supplies of food. 



The furthest tropical outpost of Australia is Thursday Island, in the 

 coral-filled Torres Strait. Here a series of islands forms a bridge between 

 the Australian mainland and the island of New Guinea. Two days spent 

 in victualling at Thursday Island provided several of us with an oppor- 

 tunity to make excursions ashore. 



Early one morning a friendly xA.ustralian took a small party in his motor- 

 launch to one of the smallest of the islands in the Torres Strait. We had 

 been told dramatic tales about all the big crocodiles we could expect to 

 find along the mangrove shores. With luck we might even see a dugong. 

 Though we kept a sharp look-out for them in the morning light, we saw 

 neither crocodiles nor dugongs. But we had a good day on a small tropical 

 bird island. 



A dozen low trees and bushes on the highest point (about five metres 

 above sea-level) formed the only "wood". Some of the trees were white 

 and leafless from the excrement of cormorants which were nesting in 

 them, and there was also an osprey's nest. Both the little pied cormorant 

 (Microcarbo melanoleucos) and the osprey (Pandion haliaetus) made off 

 when we landed. There were neither young nor eggs in the nests. 



Three species of tern flapped and screamed over our heads. Their 

 nests on the bare rocks all contained newly laid eggs. Least abundant 

 were the large Sterna bergii, a species common all round Australia. The 

 other species were typical terns, the brown-winged tern (Sterna ance- 

 theta) and a small one, rather hke the little tern (Sterna albijrons), with 

 a crescent-shaped black crown, the black-naped tern (Sterna sumatrana). 

 Altogether, I should say there would be about 50 pairs of terns. The brown- 



