36 THROUGH THE BRAZILIAN WILDERNESS 



possesses on the whole the most advertising coloration of 

 any small bird I have ever seen in the open country, and 

 moreover this advertising coloration exists in both sexes 

 and throughout the year. It is a brilliant white, all over, 

 except the long wing-quills and the ends of the tail-feathers, 

 which are black. The first one I saw, at a very long dis- 

 tance, I thought must be an albino. It perches on the top 

 of a bush or tree watching for its prey, and it shines in the 

 sun like a silver mirror. Every hawk, cat, or man must 

 see it; no one can help seeing it. 



These common Argentine birds, most of them of the 

 open country, and all of them with a strikingly advertis- 

 ing coloration, are interesting because of their beauty and 

 their habits. They are also interesting because they offer 

 such illuminating examples of the truth that many of the 

 most common and successful birds not merely lack a con- 

 cealing coloration, but possess a coloration which is in the 

 highest degree revealing. The coloration and the habits 

 of most of these birds are such that every hawk or other 

 foe that can see at all must have its attention attracted to 

 them. Evidently in their cases neither the coloration nor 

 any habit of concealment based on the coloration is a sur- 

 vival factor, and this although they live in a land teeming 

 with bird-eating hawks. Among the higher vertebrates 

 there are many known factors which have influence, some 

 in one set of cases, some in another set of cases, in the 

 development and preservation of species. Courage, intel- 

 ligence, adaptability, prowess, bodily vigor, speed, alert- 

 ness, ability to hide, ability to build structures which will 

 protect the young while they are helpless, fecundity — all, 

 and many more like them, have their several places; and 



