There is no uniformly best field method to count birds. What method is to be selected depends on, among others, the goals of a scheme, the sampling design and the availability of fieldworkers. Three main standard types of methods are available and used by national schemes within PECBMS, sometimes slightly modified for national purposes:
Point counts along a transect are called point transect counts.
The territory mapping method is probably the most precise, but it is also very time consuming and laborious. It can be used on a limited spatial scale, unless simplified version is used. Nowadays, most national schemes apply either line transect or point counts methods. Each method has its strengths and weaknesses and there is no single rule to choose from them. Standard textbooks (e.g. Bibby et al., 2000; Sutherland et al., 2004; Sutherland, 2006) and also the Best Practice Guide (Voříšek et al., 2008) give detailed overviews of the differences between these two methods.
PECBMS works with national indices rather than with raw data. Therefore, the field method used to produce the national indices is of minor concern as long as this method is standardized through years and provides a reliable, representative picture of a species’ national trend. Learn more in chapter 2, Box Missing values II.
Details on methods and monitoring schemes for each country can be found in Common bird monitoring schemes in Europe.