AVIAN GENUS CHRYSOCOCCYX 57 



The didric is generally absent from treeless grasslands, and it is 

 by this fact that we may explain the absence of terrestrial open grass- 

 land nesting birds, such as larks and most pipits, from the list of hosts. 

 Hole-nesting birds, such as starlings, are also left alone by this cuckoo, 

 and so too are the estrildine waxbills and their relatives. 



Approximately 81 percent of all parasitized nest records or records 

 of hosts feeding recently fledged didric cuckoos have to do with weaver- 

 birds, Ploceidae, with a total of 346 instances divided among 36 

 species (or 50 species and subspecies). Of these records 198 are of 

 species of the single genus Ploceus, involving 19 species (31 species 

 and subspecies), while a single species of the genus, P. velatus, accounts 

 for 105 records by itself, about a quarter of all the known instances 

 of didric parasitism. Two other species, P. capensis and P. cucullatus, 

 have 21 and 23 records, respectively. However, the bird wdth the 

 second largest number of observed instances of parasitism is, not a 

 species of Ploceus, but the red bishop, Euplectes orix, for which some 

 77 records have come to my notice. Next in frequency of choice as a 

 fosterer is the Cape sparrow. Passer melanurus, with 43 records, or 

 almost 10 percent of all the known instances of didric parasitism. 



Flycatchers, warblers, and thrushes, forming the large family 

 Muscicapidae, account for 38 records, or about 9 percent of the total, 

 distributed among 16 species, or 23 percent of all recorded hosts. Of 

 this assemblage the warblers of the genus Prinia, with 3 species, have 

 been reported as hosts 18 times, 16 of these instances being of the one 

 species, Prinia subflava. 



Sunbirds provide about 9 percent of the known hosts (six species) 

 mth 17 records, or about 4 percent of the total known instances. It 

 may be noted that Klaas's cuckoo, C. Haas, is much more partial to 

 sunbirds as hosts and correspondingly less so to weaverbirds than is 

 the didric. 



Wagtails and pipits (Motacillidae) play a somewhat lesser role in 

 the parasitism of the didric. There are in my files 12 reports of three 

 species of this family serving as hosts to the cuckoo. A single one 

 of these refers to a typical pipit (Anthus), the others concern two 

 species of wagtails {Motacilla), birds less apt to be denizens of the 

 open grasslands. Two species of Fringillidae account for seven records 

 of parasitism or about 1.7 percent of all the cases. Other families of 

 birds are less frequently used by the parasite, and all but one of them 

 are passerine birds, the one exception being the mousebird, Colius 

 colius, for which a single record (Ottow and Duve, 1965, p. 435) is 

 known to date. 



Of the 68 species of hosts, more than half (39 to be exact), are 

 kno\^^l in this relationship on the basis of single reported instances; 

 6 have been so recorded only twice; 3 each, three and four times; 



267-562—68 5 



