STRUCTURE AND SEA-BIRDS OF THE N. ATLANTIC g 



land of dense mangrove forest and a very large number of low wooded 

 islands. Off-shore the immense tonnage of mud and silt is seized 

 by the equatorial current and driven northwards towards Trinidad, 

 which it thus provides with a very wide continental shelf. As Murphy 

 (1936, p. 127) writes, "The delta of the Orinoco is not the home of 

 birds that can be called marine. . . . Only our adaptable old friend the 

 Bigua cormorant seems ... at home." 



Generally speaking, from the mouth of the Amazon to the mouth 

 of the Orinoco the coast scarcely harbours a breeding sea-bird. 

 However, the British islands of Trinidad and Tobago, off the north- 

 east corner of Venezuela are provided with rocky promontories and 

 many islets on which sea-birds nest. The brown pelican Pelecanus 

 occidentalism the red-footed booby Sula sula, the man-o'-war or frigate- 

 bird Fregata magnijicens ^ nest on low trees or on mangroves. On the 

 bare Soldado rock the sooty tern Sterna fuscata^ and the two species 

 of noddy, nest. One tubenose, Audubon's shearwater Puffinus 

 rherminieriy nests on Tobago, which is its southernmost breeding place 

 on this coast. The gull-billed tern nests in fresh water marshes. 



West of Trinidad we are in the Caribbean Sea and following the 

 coast, which for 250 miles more has a wide continental shelf, with 

 small islands dotted in it. Opposite the western part of Venezuela, 

 however, the water is much deeper close in-shore, and the off-coast 

 islands of Curasao and other Dutch possessions rise from a deep sea. 

 Both the islands of the shallow shelf, such as Los Hermanos and the 

 Testigos, and these Dutch islands, have many sea-birds, including three 

 kinds of boobies, man-o'-war birds, tropic-birds, noddies and sooty 

 terns. At least eight species of terns are found at Aruba, the western- 

 most of the Dutch islands. But there are few species which can be 

 described as oceanic, though the boobies are marine; many of the 

 sea-birds probably nest on the islands rather than on the mainland 

 because of the additional safety and the existence of outcrops of rock 

 such as are not found along the interminable mangrove coast. 



Of all coasts that we have so far considered, those of northern 

 Venezuela are the driest, and the Caribbean is the hottest part of the 

 North Atlantic region. The western Caribbean, however, has intense 

 summer rain; in spite of this, evaporation is great and the equatorial 

 current is boosted along, flowing into the Gulf of Mexico with some 

 rapidity. 



In the Antilles, which form the eastern and northern boundaries 

 of the Caribbean Sea, we find islands clad still in fairly thick jungle 



