ECOLOGICAL SURVEYS 21 



of plant associations could be usefully used or adapted 

 for animal studies. 



It is of some interest to note that ecological surveys 

 of parasites can be carried out on the same principles, 

 though not by the same techniques, as those of free- 

 living animals. For instance, a survey of the parasite 

 fauna of wood-mice {Apodemus sylvaticus) in about 

 450 acres of woodland near Oxford (Elton & others, 

 1931) disclosed some 47 species of parasites (including 

 one kind of spirochaete but not the other kinds, or 

 bacteria). The composition of this community re- 

 sembles in principle that of any other animal 

 community in a major habitat such as a wood or 

 a moor or a pond. Some species are confined to 

 Apodemus as host ; others are especially abundant 

 on Apodemus, but also occur on other hosts ; while 

 some are accidental or at any rate occasional visitors 

 from species of voles and shrews. The relation of 

 wood-mice to other animals in the community is 

 shown by such parasites as the tapeworm that occurs 

 adult in domestic cats and larval in wood-mice, and 

 by the existence of an overlapping system of flea- 

 contacts between such widely different forms as the 

 mole, the common shrew, the bank vole, and the 

 wood-mouse. Such contacts have, of course, an im- 

 portant influence on the possible spread of micro- 

 parasites during epidemics. Again, the parasites 

 found in one host can be classified according to the 

 different minor habitats they select. The wood -mice 

 had the following distribution of species : 



Ectoparasites : 



On ear : I tick larva 

 On fur : At least 12 mites 

 I tick (adult) 



I beetle 



II fleas 

 1 louse 



On anus and genital organs : 1 mite 

 Under skin of limbs : 1 mite 



