98 IT.S. NATIONAL MUSEUM BULLETIN 2 65 



cuckoos that they have retained the evicting habit in spite of their 

 wide use of "difficult" nests — certainly many of them more diflBcult 

 as eviction sites, with all the violent exertion and pushing involved, 

 than those commonly parasitized by species of the genus Cuculus. 



Fledgling feeding by adult cuckoos 



The atavistic behavior pattern of feeding fledgling glossy cuckoos 

 by adults of the same species has been observed and recorded for 

 four of the members of the genus Chrysococcyx (caprius, cwpreus, Haas, 

 and lucidus) with a total of at least 33 independent observations, not 

 counting such old, unsupported statements as that of Heuglin (1871, 

 p. 777), who noted adult caprius feeding young ones on several occa- 

 sions in October 1861, at Keren, or indefinite, dataless observations 

 along the same lines by others. These 33 cases are divided as follows: 

 caprius 15 (plus some incompletely described ones), cupreus 2, Haas 

 12, and lucidus 4 cases in print. 



The number of these definite observations is sufficient to indicate ^^ 

 that fledgling feeding is neither uncommon nor unusual, while the 

 assiduous and repetitive feedings in some of these cases make it im- 

 possible to assume that they were chance happenings which were 

 based on the reactivation of a residual responsiveness by a passing 

 adult cuckoo to the food-begging of the young. 



In earlier discussions of this intriguing and theoretically significant 

 tendency I was inclined to wonder if the actual observations might 

 not have been of instances of courtship feeding, in which case either 

 the observer assumed the fed bird to be a young one rather than a 

 potential mate or that the food-bringing cuckoo itself might have 

 mistaken a well-grown fledgling for an adult female. Some years later 

 I found that Watson and Bull (1950) had raised a similar question 

 about Hursthouse's (1944) record of fledgling feeding by the glossy 

 cuckoo, C. lucidus, in New Zealand, even though in that instance the 

 presence of the foster-parent, Gerygone igata, enhanced the likelihood 

 that the fed bird was, not an adult, but a young cuckoo. My original 

 question stemmed from the fact that the early records involved adult- 

 male cuckoos only in instances where the sex of the feeding bird was 

 specifically mentioned. Even now, with a greater number of such 

 cases on record, there is still only meager evidence that adult females 



" For pertinent references to these cases see: Baird 1945; Benson and Serventy 

 1957; Fell 1947, p. 513; Fulton 1910; Graham 1940, p. 4; Haydock 1950; Heuglin 

 1871; Holman, in Bannerman, 1933, Hursthouse 1944; Maclaren 1952, 1953; 

 MUlar 1926, 1943; Moreau 1944; Moreau and Moreau 1939; Oliver 1955; Olivier 

 1957; Ottow and Duve 1965, p. 432; Pike, in Friedmann, 1956; Robinson 1950, 

 p. 107; Smith 1957, p. 309; Symons. in Friedmann 1949a; Thomas 1960; van 

 Someren 1939; and Worman 1930. 



