22 On the trail of vanishing birds 



bills in the world, but none have the brilliant colors of the New 

 World form. These other spoonbills inhabit parts of Europe, 

 Asia, Africa, and Australia, and in general they are white birds 

 with some black or yellow in their plumage. As if to make up for 

 their lack of brilliance they sport long, pointed feathers on their 

 heads, a nauchal crest that is quite striking. 



The evolution and purpose of these varied plumages and soft- 

 part colors is in itself a fascinating subject. When we were study- 

 ing the black-crowned night herons back on Long Island we ob- 

 served that head plumes and the colors of the legs, the bill, and 

 the loral space in front of the eyes had a direct bearing on the se- 

 lection of a mate and pair formation. These ceremonies are ini- 

 tiated by the male night heron, who reaches unexpected heights 

 during these two or three weeks of high-pressure courtship. Nor- 

 mally, during the remainder of the year, a rather unspectacular 

 little heron with inconspicuous black, gray, and white plumage 

 patterns, dull-yellow legs, and creaking vocal attainments, the male 

 reacts in a most wonderful manner to the arrival of April and its 

 warmer temperatures. As a result of a partial prenuptial molt, his 

 plumage is sleek and glistening. The heavy bill is a glossy blue- 

 black and so is the bare skin of the lores. The slender white plumes 

 on the head are long and resplendent. But the most striking trans- 

 formation is in the color of the legs. Their usual yellow is now a 

 pinkish red, and we soon learned that there is a definite purpose in 

 these changes. It was our conclusion that the acquisition of red 

 legs in the night heron is an inborn character limited to a period 

 of two to four weeks out of the year. Its chief function is as a 

 releasing stimulus that serves as an indicator of readiness for pair- 

 ing. 



When you consider that birds have no intelligence as in man, 

 and when you ponder the obvious fact that flocks of birds such as 

 these night herons still manage to get together in the same place 

 at the same time and eventually produce young, you can appre- 

 ciate the importance of studies such as these. In my researches into 

 the habits of a rare species like the roseate spoonbill the part that 

 behavior studies played in our understanding of these little known 

 birds was considerable. 



