Figure
1. Results of the Layers method: this permits a precise count of the
birds incubating in a breeding colony, identification of the species,
and activity, i.e., whether the bird is incubating or standing on the
ground. Red circles - Black-headed Gulls incubating, black circles -
Black-headed Gulls standing on the ground or in the water, yellow
circles - Greylag Geese incubating and nest with eggs, blue circles –
incubating Common Terns, white squares - birds with an unidentified
activity, possibly dead.
A separate comparison of 43 images was used for the results obtained
with the predictive machine learning model. The machine learning method
requires additional assumptions and more preparatory work. 1) Images
must be 8 bits. 2) The bird size needs to be roughly the same in all
images, so downsizing is necessary using the resizing factor calculated
from the image with the objects of the fewest pixels. 3) The images must
be pseudo-normalized via automatic adjust brightness-contrast in Fiji
software (Schindelin et al. 2012, Buchholz et al. 2020).
Passin Bablok Regression was used to compare the methods. This is a
linear regression procedure with no special assumptions regarding sample
distribution or measurement errors. The result does not depend on the
assignment of the methods or instruments. The slope and intercept are
calculated with their 95% confidence interval. These confidence
intervals are used to determine whether there is only a chance
difference between the slope and 1 and between the intercept and 0
(Passing & Bablok 1983,
Bilić-Zulle 2011). The statistical
analyses were carried out using the software program R (R Core Team.
2021).
If the methods were comparable (not significantly different) with the
proxy method, the analysis execution time was compared in the next step.
Results