172 
FRANCIS H. HERRTCK 
According to Baldamus, 230 species belonging to the family 
Cuculidse have been described in both hemispheres, ranging from 
the tropics where they are most abundant, to the polar circle, 
which is sometimes overpassed by the Curculus canoriis of Europe 
in its spring migration. Of these, 140 are classed by this writer 
among the non-brooders, but this number is considerably too 
great, and but few of them seem to have been studied with suffi- 
cient care. Yet, according to Knowlton,"^ the 'evicting instinct' 
(see pp. 178-180) has been recently observed in the young of 
several species of Australian cuckoos. 
North America possesses three genera ; Coccygus (arboreal cuc- 
koos), Geococc>rx (terrestrial cuckoos), and Crotophaga (includ- 
ing the Ani or Savanna blackbird), and eight species, most of 
whch belong to the Southern States or West Indies. Two only, 
the black-billed (Coccygus erythrophthalmus) , and the yellow- 
billed cuckoo (C. americanus)^ cover a wide range and are well 
known in the Eastern and Central United States. All build nests 
and all brood and tend their young with as much devotion as 
most birds are able to show. 
The present paper deals with the development, instincts, and 
general behavior of the young and adult black-billed cuckoo 
but since its relationship with the Coccygus americanus is extreme- 
ely close, it is practically certain that in respect to behavior they 
agree in all essential respects. 
2. METHODS AND OBJECTS OF STUDY 
Observations on the life and behavior of nesting birds, and here 
I chiefly refer to passerine and other land birds of the interior, 
which are exact, continuous, and fairly complete, can hardly be 
said to exist, and for this reason, I shall tabulate such results as 
have been obtained for the black-bill, however incomplete, with 
considerable detail, only regretting my inabilit}^ at this time to 
3 Knowlton, Frank H. Birds of the World, Am. Nature Ser. p. 443. New 
York, 1909. 
* When American cuckoos are mentioned, without further qualification, in 
this paper, these two species only are referred to. 
