AVIAN GENUS CHRYSOCOCCYX 55 



Chalcomitra olivacea and Chalcomitra senegalensis, and a weaver, 

 Ploceus reichenowi; 3 species are known from two records each, while 

 the other 21 have been noted as victims of this cuckoo but once. 



The present list of fosterers is weighted, probably undiJy, on the 

 side of species occurring in the open woodlands and brush country 

 rather than in the dense forests, but the emerald cuckoo is much more 

 of a forest dweller than is either the didric, C. caprius, or Klaas' 

 cuckoo, C. klaas. Observation is generally more difficult in heavy 

 forests than in more open country, and, consequently, fewer nests are 

 found in the former areas. It may be expected, however, that in time 

 an increasing number of piu-ely sylvan birds will be added to the host 

 catalog of the emerald cuckoo. Thus, not a single species of forest 

 bulbul has yet been found to be victimized, but, if we consider the 

 frequency with which Pycnonoius barbatus is affected in the more open 

 areas, it woidd seem probable that some of its sylvan relatives also are 

 imposed upon. 



In light of the above there is only little to be gained by estimating 

 the proportional role of the various passerine families in the economy 

 of the emerald cuckoo. It is true that oiu" present data suggest that 

 the weaver bu'ds (Ploceidae), with 12 species of hosts out of the total 

 34 and 20 instances out of the 60, rank first; the sunbirds (Nectarinii- 

 dae), with 6 species of hosts and 14 instances come second; the warbler, 

 flycatcher, and thrush assemblage (Muscicapidae), with 6 species and 

 9 records, and the bulbids, also with 9 records but only a single host 

 species, come next, followed by the white-eyes (Zosteropidae), with 

 4 species and 4 records. However, when more complete data on forest- 

 dwelling birds become available, it will undoubtedly be necessary to 

 alter this arrangement. 



The currently known hosts are as follows: 



Motacilla capensis Cape wagtail 



Pycnonotus barbatus Yellow-vented bulbul 



Parisoma subcaeruleum Tit-babbler 



Dioptrornis Jischeri White-eyed slaty flycatcher 



Plaiysteira peltata Black-throated wattle-eye 



Horizorhinus dohrni Dohrn's thrush babbler 



Terpsiphone rufiventer Red-bellied paradise flycatcher 



Terpsiphone viridis Paradise flycatcher 



Prinia subflava Tawny-flanked longtail 



Ofiolus larvatus Black-headed oriole 



Dryoscopus gambensis Gambian puff-backed shrike 



Dryoscopus cubla Puff-backed shi'ike 



Zosterops virens Green white-eye 



Zosterops Jicedulinus Princip^ white-eye 



Zosterops griseovirescens Annobon white-eye 



Speirops leucophaea Princip^ speirops 



