l8 SEA-BIRDS 



or finger-holds improved and enlarged by the mud-construction of 

 their nests, tysties or black guillemots in talus and boulders at the foot 

 of the cliff. These wild, steep frontiers between sea and land are exciting 

 and beautiful. They probably house larger numbers of vertebrate 

 animals, apart from fish, in a small space, than any other comparable 

 part of the temperate world. 



Not many sea-birds of the east Atlantic do not breed on clifis; 

 but the skuas nest on moors, and the terns and black-headed gulls 

 nest on sand and shingle. Many of the Larus gulls, and recently the 

 fulmar, are catholic in their taste in nesting sites, and may be found 

 on moors and even sand dunes. Quite a large number of sea-birds can 

 be inland nesters, even including tubenoses. Fulmars now nest up 

 to six miles inland in Britain, and many of the Larus gulls at much 

 greater distances. The black-headed gull, in particular, is often a 

 completely inland species, since some individuals nest in England as 

 far as they can from the sea, e.g. in Northamptonshire, and may never 

 visit it except in casual search for food. 



As we go south along the Atlantic seaboard of the Old World 

 we leave behind in the Channel Islands and Brittany the last elements 

 of certain temperate cliff-breeding sea-bird species — the gannet, 

 lesser blackback, great blackback, arctic tern (only a casual breeder 

 so far south), razorbill and puffin. South of the Bay of Biscay we en- 

 counter a large sub-tropical and tropical community of about forty 

 species (a few of which belong to sea-bird families but which have 

 become river-birds or inland birds), which is distributed in four main 

 geographical regions — the Lusitanian coast (the Atlantic coast of 

 Spain and Portugal), the Mediterranean, the Atlantic coast of Africa 

 north of the equator, and the Atlantic Islands. These last comprise 

 the Azores, Madeira (to which pertain the Desertas and Salvages), 

 the Canaries and — near the equator — the Cape Verde Islands. Many 

 species breed, of course, in more than one of these regions, though 

 only the herring-gull (rather doubtfully the little tern and cormorant) 

 breeds in them all. 



Of the species in the table, the crested pelican Pelecanus roseus, the 

 pigmy cormorant Halietor pygmeus, the Mediterranean black-headed 

 gull Larus melanocephalus, and the lesser crested tern Thalasseus bengalensis 

 breed on no North Atlantic shore, and the rare slender-billed and 

 Audouin's gulls, Larus genei and L. audouinii, are primarily Mediterranean 

 species. It will be noted that three tubenoses have established them- 

 selves in the Mediterranean, but that no less than eight species breed 



