Fig. 2. Comparison of methods using Passing Bablok regression. The graphs show the observations with the regression line (solid line), the confidence interval for the regression line (dashed lines) and the identity line (x=y, dotted line). Comparison between the proxy methods and other methods: Denoiseg, Click Tool, Fiji, Hand and Photoshop Auto.
The Layers method was the most time-consuming, the average time needed to count 100 birds being 893 seconds. Birds were counted the fastest using the neural networks machine learning method (Denoiseg) – an average of 100 birds in 23 seconds. All methods except Denoiseg exhibited a significant correlation between the number of birds in the group and the time needed to count them: the more birds, the longer it took to count them. With the Denoiseg method, the number of individuals in a group did not affect the time needed to count them.
Table 5. Average time needed to count 100 individuals in a group of birds and correlation with the size of the group.