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?
Whether species are included in PECBMS indicators depends on
- species classification (i.e. whether a species has been selected for a given type of indicator,
- species data quality, and
- species data availability.
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.