AVIAN GENUS CHRYSOCOCCYX 37 



a considerable range in body size, as is true throughout the entire 

 range of Chrysococcyx, it might be expected that the small species, 

 such as the various glossy cuckoos, woidd tend to parasitize relatively 

 small birds and that larger cuckoos (Cuculus, Clamator, Urodynamis, 

 Eudynamis, etc.) would utilize primarily the nests of larger hosts. 

 In a very general way this is what we find, but in Asia and Australia 

 the presence of cuckoos of intermediate size of the genus Cacomantis 

 does complicate the situation to some extent. Still, it may be said 

 that there is a general tendency for size correlation between hosts 

 and parasites, although the limits are by no means rigid or constant. 

 This is different from what may be observed in Europe, where Cuculus 

 canorus, having no competition from other cuckoos, utilizes a great 

 range of small fosterers, many of them as small as the smallest hosts 

 of the small glossy cuckoos. 



In Africa the glossy cuckoos (capritts, cupreus, and klaas) overlap 

 relatively seldom with the larger cuckoos of the genera Cuculus, 

 Clamator, Pachycoccyx, and Cercococcyx in their choice of hosts. 

 Strangely enough, the fosterers most frequently serving both Chryso- 

 coccyx and Cuculus are the wagtails, Motacilla, and these birds are 

 the only ground-nesting species used with any regularity by the 

 glossy cuckoos. The African glossy cuckoos use primarily species of 

 weavers, sunbirds, warblers, and flycatchers, and relatively seldom 

 parasitize babblers, thrushes, shrikes, and (except for Chrysococcyx 

 cupreus) bulbuls, to say nothing about hole-nesting starlings and such 

 larger birds as piapiacs and crows, used extensively by Clamator 

 glandarius. 



In India, Burma, Siam, and Malaysia, the glossy cuckoos {maculatus 

 and xanthorhynchus) do overlap in their host choice with Cacomantis 

 merulinus (less so with Cacomantis variolosus), while in Australia 

 they (lucidus, basalis, malayanus, and osculans) find themselves in 

 regular and apparently not unequal competition for many of their 

 usual hosts with several species of Cacomantis (variolosus, pyrrho- 

 phanus, and castaneiventris) , also with Cuculus pallidus, and, in New 

 Zealand, even with Urodynamis taiiensis. To take but a single recent 

 study of the situation in Australia, Rowley (1965, pp. 274-275) 

 found the blue wren, Malurus cyaneus, to be parasitized by no less 

 than six species of cuckoos, three glossy cuckoos — lucidus (plagosus), 

 basalis, and osculans, by two species of Cacomantis (pyrrhophanus 

 and variolosus) , and by Cuculus pallidus. 



Lest it may seem that excessive use of a single host species by 

 multiple parasites be self-defeating to the extent of seriously de- 

 pleting the host population, we may recall McGilp's paper (1929, 

 p. 298) in which he discussed a situation "where the Spotted Scrub- 

 Wren (Sericornis maculata) [sic] is the foster-parent of several species 



