ECOLOGICAL SURVEYS 9 



lively few species (Summerhayes and Elton, 1923 and 

 1928). Where a more complex survey is contem- 

 plated, it is essential to work in a team or group, 

 which can divide up some of the different sections of 

 the work. Thus, in surveying the animal community 

 of any British vegetation type such as a heather moor 

 or a wood or a swamp, it is usually found convenient 

 to have about three or four different collectors at 

 least. One man can do the birds, another the other 

 vertebrates, a third the insects, and if possible another 

 man the remaining invertebrates. In addition the 

 help. of a botanist will be needed, to give a check 

 on the vegetation. This is especially important at 

 the start, in choosing a suitable area for the field 

 work. The vegetation types give a fair indication 

 of many of the other features of the environment, 

 so that it is an advantage to choose vegetation that 

 is representative of some widespread type. By doing 

 this the survey of animals will have more than a 

 purely local significance, and can be compared with 

 later work in other places. It is of vital importance 

 to define very exactly the nature of the environ- 

 mental factors of the habitats. This subject will be 

 treated more fully m Chapter IV, As regards general 

 methods of surveying, reference may be made to 

 Elton (1927), who gives also a list of systematic books 

 and papers dealing with various groups of British 

 animals. These books and papers mostly contain 

 notes of the technique of studying each group, as 

 well as keys for their identification. It is seldom safe 

 to identify species without expert confirmation. And 

 in all ecological surveys it is essential to retain full 

 collections of specimens for permanent reference. 

 This means in practice that the collections should go 

 to some museum, where they can be safe against 

 casual accident or faulty preservation. This method 

 of depositing the specimens from ecological surveys 

 has been successfully adopted by many expeditions, 

 and should also be more often adhered to by private 



