g2 FLEAS, FLUKES AND CUCKOOS 



found in South America on birds such as the cheu-can {Pteroptochus 

 rubecula) and it is a group which certainly originated in the Neotropical 

 Region. D. gallinulae is also found in British Columbia (North America) 

 where it has developed into a distinct sub-species. Possibly this is the 

 route by which Europe received this single representative of the South 

 American fauna. The other genus is represented by one of the most 

 interesting fleas in Britain, Orneacus rothschildi, of which nine specimens 

 only are known*. These were taken from a house-martin's nest situated 

 on the cUffs at Kinneff on the east coast of Scotland. A shghtly different 

 subspecies of the same flea was collected in the Swiss Alps by Jordan 

 and Rothschild. The other known species of this genus was found in a 

 martin's nest in Ladakh, Kashmir at 10,500 feet. These fleas are derived 

 from quite another group of mammal fleas, the genus Citellophilus, 

 parasitising ground squirrels (Citellus), and with these they show a 

 striking affinity. It is difficult to guess the place whence the Scottish 

 martins got these fleas. The fossil record proves that the mammal 

 Citellus was present in Britain (Thames Valley) in the Pleistocene many 

 thousands of years ago. The nearest species of Citellophilus to-day, 

 however, is found in the Pyrenees. It is probable that the switch-over 

 from ground squirrels to house-martins took place somewhere in the 

 Palaearctic region, but the possibility cannot be ruled out that Orneacus 

 was brought to east Scotland by migrating martins which had picked 

 up the fleas on their travels. 



The common house-martin flea {Ceratophyllus hirundinis) as we have 

 seen has a very wide distribution and is also found on the martins 

 breeding in Kashmir. 



It has already been mentioned that among British bird fleas there is 

 one representative of the family PuHcidae (to which the human flea 

 Pulex irritans belongs) . This is the shearwater flea, Ornithopsylla laetitiae, 

 descended from one of the rabbit fleas of North America. In the Palae- 

 arctic region there is only one species of rabbit flea of this family found on 

 the common rabbit and one (Hoplopsyllus glacialis) on the arctic hare 

 but in North America there are at least ten species and sub-species. 

 Puffins and rabbits Hve in close proximity — even using each other's 

 nesting burrows — on the rocky islands off the coast of Britain. In 

 fact our rabbit flea has been taken off the puffin on Skomer Isle. 

 The first idea that occurs is that the common rabbit flea at some 

 remote period passed on to the puffins and shearwaters, and gradually 

 ♦Since re-discovered in Aberdeenshire (Allan 1950). 



