102 BULLETIN 17 6, UII^TITED STATES NATIONAL MUSEUM 



and their progress on the ground very slow, similar to the progress 

 of certain woodpeckers when hunting a lawn for ants and other 

 prey. 



As a rule they feed in trees at some height from the ground, but 

 any plague of caterpillars will tempt them down to quite low under- 

 growth or even onto low grass in the open, and I once saw four 

 cuckoos all feeding on small green caterpillars on the ground in an 

 open glade in pine forest. 



Behavior. — Normally cuckoos are seldom found on any but high 

 trees, often resting in one position for a long time on some lofty 

 branch and then flying to another tree with strong, easy beats of the 

 wing, at a considerable speed. In the breeding season the females 

 undoubtedly mark down the nests in which they intend to deposit 

 their eggs, and they may be seen perched in a tree, watching their 

 victims until these latter give away the position of the nest. While 

 thus engaged the patience of the cuckoo seems inexhaustible, and 

 it will sit for hours in one position, hardly moving, yet_ obviously 

 watching the intended fosterers, which may be loath to return to 

 their nests though they may come and perch on the same tree as 

 that occupied by the cuckoo, sometimes within a few feet of her. 

 Apparently they not only mark down nests for immediate victimiza- 

 tion, but others to be made use of when later eggs are to be laid. 

 At other times they seem to be able to ascertain the approximate, 

 yet not the exact, position of a nest. (Livesey (MS.) gives me a most 

 interesting example of this. He writes : 



"Yesterday, May 19, 1937, I was out for a walk with my wife 

 about 5 p. m. at Taungyi, which has an elevation of some 5,000 feet. 

 Close to my cottage the dogs chased a bird off a ploughed field, 

 which I recognized as a cuckoo. The cuckoo returned with 

 two chats after her and perched on some bamboo rails, so, suspect- 

 ing that the chats had a nest somewhere near in which the cuckoo 

 was going to lay, I sat down to wait and watch with my glasses. 

 Back came the cuckoo and flew low over the field almost settling on a 

 place some 50 yards in front of us. Twice she flew backward and 

 forward, chased by the chats, finally settling where I expected the 

 nest to be. I could see her very plainly through the glasses as with 

 throat feathers puffed out and crest feathers sometimes raised she 

 jumped clumsily from clod to clod searching for the nest, straining 

 her neck up and looking everywhere. The chats were now mobbing 

 her furiously and in retaliation she only opened her beak and made 

 faces at them. She did not appear to know where the nest was and 

 began a systematic search for it in an area about 5 by 3 yards. The 

 clods in the field were very large and lumpy with all sorts of holes 



