NO. 4 AVIAN GENUS CLAMATOR — FRIEDMANN 49 



of Clamator. Baker (1942, p. 152) has claimed otherwise, and he 

 had behind him many years of experience, even if not of the most 

 critical sort, when he wrote that ". . . several eggs of all the species 

 of the genus Clamator . . . may be found in the same nest, obviously 

 the production of two or more Cuckoos . . . For instance, in the set 

 with six Pied Crested Cuckoos' eggs it is easy to see that they 

 must have been laid, two each, by three different cuckoos . . ." Yet, 

 elsewhere in his work he stressed the fact that each species of 

 Clamator lays a single, invariable egg type. The only variations that 

 might be expected would be quite minor, and in many cases these 

 would hardly suffice to distinguish the eggs of individual parents. 



In the case of C. glandarius the greater variability of eggshell pat- 

 tern makes it possible to distinguish between multiple eggs of the 

 same hen and eggs of different individual cuckoos. Here there are 

 acceptable records of more than one parasite laying in the same nest. 

 Mountfort and Ferguson-Lees (1961, pp. 98-99) found as many as 

 three cuckoos laying in single nests of magpies in Spain. What 

 is true of glandarius, and, it seems, of coromandus, may or may not 

 be true of jacobiniis and levaillantii. There are not yet the necessary, 

 careful observations to prove or to disprove this in these two species. 



Because of this it is not profitable at this time to attempt to 

 particularize our discussion of multiple parasitism in Clamator below 

 the species level. In instances of maximal numbers of eggs in single 

 nests it is highly probable that multiple hens were involved, but in 

 cases of two, or even three, eggs in a nest, there is no certain way of 

 telling. 



Brood parasitism is a more precarious mode of reproduction than 

 is self-breeding, as it involves all the risks normally attendant upon 

 the nests it utilizes plus the elements of desertion of the nests or 

 destruction of the eggs by the hosts. It is therefore plausible that any 

 improvement, or any increased discrimination, in the matter of tgg 

 deposition would provide a basis on which natural selection would 

 operate and, conversely, a basis from which the effects of such selec- 

 tion might be inferred. By and large, the chances of success for the 

 parasite tend to decrease when more than a single egg is laid in the 

 same nest. Many hosts may stand for a single imposition but not for 

 repetitive ones without deserting the nest ; others simply could not 

 hatch and rear more than one or two of the parasitic young. It 

 follows, therefore, that an original tendency to lay multiple eggs in 

 the same nest would eventually be modified by natural selection, and 

 that the relative frequency of such multiple eggs would tend to de- 

 crease in areas where selective pressure was in operation. 



