122 HEADWATERS OF THE PARAGUAY 



sometimes bothered by numbers of biting horse-flies. 

 The bird-life was wonderful. One of the characteristic 

 sights we were always seeing was that of a number of 

 heads and necks of cormorants and snake-birds, without 

 any bodies, projecting above water, and disappearing as 

 the steamer approached. Skimmers and thick-billed 

 tern were plentiful here right in the heart of the conti- 

 nent. In addition to the spurred lapwing, characteristic 

 and most interesting resident of most of South America, 

 we found tiny red-legged plover, which also breed and 

 are at home in the tropics. The contrasts in habits 

 between closely aUied species are wonderful. Among 

 the plovers and bay snipe there are species that Hve all 

 the year round in almost the same places, in tropical 

 and subtropical lands ; and other related forms which 

 wander over the whole earth, and spend nearly all their 

 time, now in the arctic and cold temperate regions of 

 the far north, now in the cold temperate regions of the 

 south. These latter wide-wandering birds of the sea- 

 shore and the river-bank pass most of their lives in 

 regions of almost perpetual sunlight. They spend the 

 breeding season, the northern summer, in the land of 

 the midnight sun, during the long arctic day. They 

 then fly for endless distances down across the north 

 temperate zone, across the equator, through the lands 

 where the days and nights are always of equal length, 

 into another hemisphere, and spend another summer of 

 long days and long twihghts in the far south, where the 

 antarctic winds cool them, while their nesting home, at 

 the other end of the world, is shrouded beneath the iron 

 desolation of the polar night. 



In the late afternoon of the 5th we reached the 

 quaint old-fashioned little town of Sao Luis de Caceres, 

 on the outermost fringe of the settled region of the 



