28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I46 



relatively recent development. The surprising thing is not only that 

 it was able to make this change, but that it had previously gone so 

 far in the road of adaptive specialization to a host with which its area 

 of sympatry was so limited. 



The magpie genus Pica occurs throughout Europe, including the 

 Mediterranean islands, and Asia north of the tropics (i.e., north of 

 the Arabian Peninsula, Baluchistan, Pakistan, India, Burma, Assam, 

 and the Malayan countries), east to the western part of North 

 America, and south from Gibraltar to northwestern Africa (Morocco, 

 Tunisia, Algeria). In all the vast extent of this primarily Holarctic 

 range, it is sympatric with its "highly adapted" brood parasite, 

 Clamator glandarius, only in the Iberian Peninsula, adjacent portions 

 of northwestern Africa (Morocco, Tunisia, Algeria), parts of south- 

 eastern Europe, Cyprus, and the Near East as far as Iran. This 

 area of sympatry is thus a somewhat peripheral part of the range, 

 both of Pica and of Clamator glandarius (whose geographically 

 most extensive range is African south of the Sahara all the way to 

 the Cape, and in eastern Egypt). An instance of the degree of 

 sympatry of C glandarius and Pica in southwestern Europe is the 

 absence of both from the Balearic Islands although both occur in the 

 Iberian Peninsula and in Morocco. 



If the &gg coloration of Clamator glandarius evolved to match that 

 of Pica, this must have taken place in this limited area where the two 

 occur together. The bulk of informed opinion regards the close 

 ^gg resemblance as something arrived at by adaptive evolution, and 

 not as a fortuitous coming together of a parasite and a host whose 

 eggshells were similar in color, pattern, and size. The latter inter- 

 pretation would assume an improbable and unlikely happening, al- 

 though it cannot be ruled out as a possible explanation. The fact that 

 throughout its range, the great-spotted cuckoo lays only this one 

 type of ^gg suggests that its original range was just those areas 

 where its tgg type was adapted to a prevalent host. This further 

 suggests that the PzVa-allopatric portions of its present range in 

 Egypt and in Africa south of the Sahara must have been a more 

 recent extension of its distribution. 



Amadon (1947) ascribed a marked change of bill form and of 

 feeding habits in a Hawaiian honeycreeper, genus Hemignathus, 

 to a sudden ecological shift of its ancestral population. Mayr (1959, 

 pp. 177-178) considered that such a shift into an entirely new 

 ecological niche may well have been the type of occasion attendant 

 upon the emergence of many major evolutionary novelties. When 



