Which criteria are used to include a particular species in an indicator or not? E.g. why is Picoides tridactylus not included in the forest bird indicator?
AnswerWhether species are included in PECBMS indicators depends on
As a consequence, some suitable species are excluded because they are not properly monitored. There is however ongoing effort to increase data availability, using for example data from species specific monitoring schemes in European countries next to generic breeding bird monitoring schemes.
See more in Methods, chapter 3, Box Species selection and classification or chapter 4. Quality control.