Comparison of counting methods
30 photos of bird assemblages were selected and analysed using different methods. A stopwatch was used to measure the time needed to process and count the birds. The Photoshop layers method allows one to zoom in on the image in order to check whether the bird should be added to the result. This enables the identification of species in a group and the activity performed by the bird (e.g. in a breeding colony, whether a bird is incubating), i.e. information relevant to the interpretation of data (Fig. 1). Thus, the results obtained with this method were taken as reference values (proxy method). Then the count precision was compared with the proxy method using different methods.