g8 FLEAS, FLUKES AND CUCKOOS 



mammal fleas which has been noted in Russia for these periodical mass 

 movements is closely related to the bird Geratophyllids. In this case 

 most of the fleas move out of the burrows at night, but on several 

 occasions Waterson in Scotland witnessed large swarms of hungry fleas 

 leaving birds' nests in broad dayhght. They bit viciously at him when 

 they landed on his outstretched arm. Possibly climatic changes or hunger 

 initiate the exodus. In Finland one observer noted that the common 

 hen flea migrates from open nests if the temperature falls below i4°C. 

 However, little or no research has been done in this field, so we can 

 only speculate. 



As we have explained (p. 136) the Mallophaga have evolved 

 the habit of "hitch-hiking" or phoresy, as it is called technically, as a 

 means of reaching another host when their own dies; there are at least 

 two records of them attaching themselves to fleas ! However, fleas, with 

 their highly developed powers of leaping do not apparently make use of 

 winged flies for transport. A few moments after the bird dies they come 

 to the surface of the feathers and jump off into the blue. There is one 

 known case, however, when a bird flea was found on a queen wasp and 

 another in a wasp's nest. Wasps being carnivorous may have picked up 

 the fleas when visiting corpses. This type of relationship often escapes 

 notice and although these two occurrences are probably accidental, it is 

 well worth looking out for further evidence of association between bird 

 fleas and wasps. 



Effect of Fleas on their Bird Hosts 



Mammal fleas are notorious carriers of disease. As vectors of 

 bubonic plague they have been directly responsible for the deaths of 

 millions of rats and miUions of men. A large number of less well known 

 diseases are also spread by them. Thus they carry a roundworm 

 {Filaria) which eats out the hearts of dogs, besides several of the common 

 tapeworms, for which they serve as intermediate host. They spread at 

 least two serious diseases among rabbits and hares, one of which, 

 tularemia, can also affect other animals including man. They act as the 

 intermediate host for a species of trypanosome (T. lewisi) parasitic 

 in rats and another in rabbits, and they can also become infective for 

 endemic typhus. Salmonella and possibly leprosy. So far, however, they 

 are not known to be vectors of any serious disease of birds although bird 



