Data are collected mainly by volunteers. How it is assured that volunteers properly collect the data? Do volunteer based monitoring schemes produce results that are as trustworthy as those from professional fieldworkers would be?
National organizers are keen to recruit volunteers with considerable experience in observing and recognizing birds. In fact, to produce reliable results, the involvement of volunteers is valuable, according to Schmeller et al. (2008):
“Because precision is a function of the number of monitored sites and the number of sites is maximized by volunteer involvement, our results do not support the common belief that volunteer-based schemes are too noisy to be informative. Just the opposite, we believe volunteer-based schemes provide relatively reliable data, with state-of-the-art survey designs or data-analysis methods, and consequently can yield unbiased results. Quality of data collected by volunteers is more likely determined by survey design, analytical methodology, and communication skills within the schemes rather than by volunteer involvement per se.”