388 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loe 



both robin eggs had been ejected from the nest. One lay on the ground 

 at the base of the tree and the other lay in a fork of the tree beside 

 the nest. Fortunately, neither egg was visibly damaged. Reed 

 replaced one egg in the nest with the cuckoo chick and watched the 

 bird try immodiatel}^ to eject it. However, when the chick had gone 

 through the performance of carrying the egg on its back to the edge of 

 the nest and the egg had rolled back into the nest, Reed removed it. 

 He repeated the experiment on January 4 with the same result, but 

 when he tried again on January 5 he was unable to induce the chick 

 to attempt to eject the egg. To make quite certain that the bird 

 had lost all desire to eject it, ho placed the egg on its back, but the 

 chick lay passiveh^ and made no attempt even to remove it. Reed 

 then broke both robin-chat eggs and found no sign of incubation in 

 them. 



Another nest was found by the same observer on November 29. 

 It contained a newly hatched cuckoo and a robin-chat's egg. On 

 December 2 the host's egg was found lying on the ground just below 

 the nest. Reed replaced this egg in the nest two da3'-s later, but not 

 even putting it directly on the back of the chick would induce the 

 latter to attempt to evict it. The young cuckoo was at least 6 days 

 old at that time; therefore, this case agrees with the more fully de- 

 scribed one in that the instinct to eject the nest-mates was found to 

 disappear before that age. 



Near Cape Town, Liversidge (in litt.) watched a nest of a Cape 

 robin-chat containing one egg of the cuckoo and one of the host and 

 made detailed notes. (Also, he kindly supphed the photographs for 

 use in this paper.) The cuckoo egg hatched, and within 24 hours the 

 host's egg was out of the nest. Liversidge put it back, but a few houis 

 later, when Dr. Broekhuysen visited the nest, it was out again. The 

 lady in whose garden the nest was located was asked to keep up 

 observations, to replace the egg in the nest each time, and to see how 

 often the young cuckoo would evict the egg. After three more 

 evictions in 10 minutes, the observer lost some of her attentiveness 

 but reported that the chick threw out the egg many more times that 

 day, the total of such evictions being in excess of 25 by the time the 

 observations were called off. The chick was later given eggs of various 

 sizes and shapes, and even small stones, all of which it evicted, or, at 

 least, attempted to eject. This went on until its fourth day. On 

 the fifth day an egg, when placed in the nest, was allowed to remain 

 there, but the ejection movements of the j'^oung cuckoo could still be 

 induced by prodding its back. Liversidge writes that the chick did 

 not have any hollow space on its back, which was quite broad and flat. 

 Wlien ejecting an object, however, the back becomes slightly concave, 

 as in the case of the well known European species, Cuculus canorus. 



