no FLEAS, FLUKES AND CUCKOOS 



THE ROCK-DOVE FLEA, Ceratophyllus columbae (Plates XIII, XV, 

 XVIIIc). Life in caves brings the various occupants into faidy close 

 proximity and favours the exchange of parasites. It also provides a 

 certain degree of isolation from the outside world. It is, therefore, not 

 surprising that our rock and cave dwelling pigeon [Columba livid) 

 should be the one pigeon to harbour a specific flea parasite. In the past 

 there has been much controversy concerning the origins of the domestic 

 bird, although it is now generally agreed that it is the same species as the 

 rock-dove. The presence of C. columbae on the wild rock-dove and on 

 our domestic pigeon is another piece of evidence in support of this 

 theory. C. columbae has never been recorded in Britain from the stock- 

 dove and only once from the wood-pigeon, and this was in London 

 where it can be regarded as a straggler from a tame pigeon. It also 

 occasionally wanders on to sea birds which nest on rocky cliffs. 



C. columbae is a particularly easy species to identify, especially in the 

 male sex, which has a characteristic bundle of bristles right at the end 

 of the eighth sternite. Its absence from the dove cotes of the United 

 States has been noted by Jordan. 



THE DUCK FLEA, C. garei, and the boreal flea, C. borealis (Plates 

 XII, XV, and Map 2; see also p. xiii). These two fleas, which 

 are almost black to the naked eye, are so alike that only a 

 specialist can be expected to tell them apart. Both are primarily 

 parasites of ground-nesting birds, and C. garei is the only British flea 

 which can tolerate the conditions found in ducks' nests. It is recorded 

 from the eider duck, pintail, shoveler, red-breasted merganser and so 

 on, hosts from which no other British bird flea has been taken. Never- 

 theless, it is at home in a really large range of nests, and in Britain alone, 

 is recorded from 48 different species of birds, including such widely 

 different hosts as the corn-crake, bearded tit, redshank, wryneck, artic 

 skua, long-eared owl and goldfinch. 



Its range extends from the Shetlands south to Cornwall and it is 

 also recorded from Ireland (Map 2). 



C. borealis has a much more restricted habitat and is found in Britain 

 only in the outlying Western Islands and Orkney (see p. 87). In this 

 country it appears to have a slight preference for the wheatear and 

 has also been collected from the same host on the Island of Ushant 

 during the birds' return passage from Africa. The only flea known 

 from the cuckoo is C borealis also taken from a specimen in Ushant. 



