NO. 2298. THE GUANO BIRDS OF PERU—COKER. 477 



July) and many eggs and even a few young nestlings were found. 

 It is evident, therefore, that there is scarcely a "closed season" for 

 parental responsibilities in this species. 



Occasionally a wanderer bird is seen to be driven relentlessly from 

 place to place as it works its way through the crowd. What was 

 the significance of this I could not detect; whether it was a bird 

 away from the proper nest or one without a mate, its unwelcome- 

 ness v/as unmistakable. 



It is the habit of the guanays to remain on the islands the greater 

 part of the time. They appear to leave only in search of food. They 

 form, indeed, a great "breeding class." They walk more than either 

 of the other Peruvian spegies of cormorant and their erect position 

 and v/addling gait is quite suggestive of the penguin. At a casual 

 glance the birds in the photograph (pi. 61) might easily be mistaken 

 for penguins. 



Unlike pelicans, the guanays will return to some extent to rook- 

 eries whence they have been disturbed during the preceding season, 

 although a preference for undisturbed islands was most clearly indi- 

 cated by the growth of the flock on the South Chincha Island. When 

 I revisited the island in 1908, a considerable number of guanays were 

 still using the Ballestas islands, although the rookery was entirely 

 broken up in the preceding year. 



When one approaches a rookery the guanays crowd away with 

 much gi-umbling, and when once a few birds arise in fhght, the move- 

 ment is liable to spread through the entire flock until hundreds of 

 thousands are on the ^ving, even most of those that were too remote 

 from the intruder to know the cause of the disturbance. It was 

 found with these, as with other birds, that, if one waits motionless 

 and with much patience, the birds will after a while return to the 

 nests and gradually close around the observer, until at last only a 

 circle with radius of 3 or 4 feet is left vacant. While in every direc- 

 tion one is surrounded by acres of birds all of a single species, the 

 scene is yet peculiarly variegated. In one direction the birds are 

 turned watchfully toward the intruder, and the thousand white 

 breasts make a glistening white groundwork spotted with black 

 heads; in another direction the birds are turned in side view so that 

 the breasts show only as white streaks. Additional effects are caused 

 according as the birds are more or less compactly grouped. Close 

 around one, the metallic green heads, the green-lustred backs, sides 

 and legs, the white throats, breasts, and bellies, and the hundreds of 

 intent green eyes are most conspicuous. The voice of a single bird is 

 a sort of a croak, less deep, less hoarse, and less powerful than that 

 of a bullfrog, but somewhat of that character. The collective voice 

 of the flock of hundreds of thousands is indescribable except as it 



