Species indices and trends are produced for Europe and its regions (Central & East, North, South, West, and Southeast Europe, East Mediterranean and West Balkan) and EU and its regions: New (since 2004) and the Old EU Members States.
Due to Brexit in February 2020, we calculated all EU bird indicators by excluding data from the United Kingdom. We removed the UK data from the whole time series to create the indicators without the country that is no longer considered a part of the EU. EU indicator calculation without the UK was done for the first time in 2022 update (the 2021 update was based on data until 2019 when the UK was still an EU Member State). Therefore, since year 2022, the EU and Old EU indices, trends and indicators are based on EU countries without UK and Malta. It is possible to compare the ‘EU indicator without the UK’ and ‘EU indicator with the UK’ in one graph on the PECBMS webpage.
The species indices are always computed for the maximum time period given by the country with the longest data set within the region (e.g. indices for West Europe are produced since 1966 given by the starting year of the indices from the UK, while indices from South Europe are produced since 1989 given by the starting year of indices from France – see an overview below).
Overview showing list of 30 countries, their start years and region that each country belongs to:
| Country/region | Region (group of countries) | First-year | Last year |
| Andorra | SE | 2011 | 2022 |
| Austria | WE | 1998 | 2022 |
| Belgium-Brussels1) | WE | 1992 | 2022 |
| Belgium-Wallonia1) | WE | 1990 | 2022 |
| Belgium-Flanders1) | WE | 2007 | 2022 |
| Bulgaria | SEE | 2005 | 2022 |
| Croatia | West Balkan | 2014 | 2022 |
| Cyprus2) | East Mediterranean | 2006 | 2022 |
| Czech Republic | CEE | 1982 | 2022 |
| Denmark | WE | 1976 | 2022 |
| Estonia | CEE | 1984 | 2022 |
| Finland | NE | 1975 | 2022 |
| France3) | SE | 1989 | 2021 |
| Germany East4) | CEE | 1991 | 2021 |
| Germany West4) | WE | 1989 | 2021 |
| Greece | SEE | 2007 | 2022 |
| Hungary | CEE | 1999 | 2022 |
| Italy | SE | 2000 | 2022 |
| Latvia5) | CEE | 1995 | 2022 |
| Lithuania | CEE | 1994 | 2022 |
| Luxembourg | WE | 2010 | 2022 |
| Netherlands | WE | 1984 | 2022 |
| Norway6) | NE | 1996 | 2022 |
| Poland | CEE | 2000 | 2022 |
| Portugal | SE | 2004 | 2022 |
| The Republic of Ireland | WE | 1998 | 2022 |
| Romania | SEE | 2007 | 2022 |
| Slovakia | CEE | 2005 | 2021 |
| Slovenia | West Balkan | 2008 | 2022 |
| Spain | SE | 1998 | 2022 |
| Sweden7) | NE | 1975 | 2022 |
| Switzerland | WE | 1999 | 2022 |
| United Kingdom | WE | 1966 | 2022 |
Explanations:
WE – West Europe
NE – North Europe
SE – South Europe
SEE – Southeast Europe
CEE – Central & East Europe
First year – the first year of data time series in a country/region
Last year – last year of data time series in a country/region
Time series for individual species from national schemes are shorter in certain cases.
Countries notes:
1) Data for Belgium were combined from Wallonia, Brussels and Flanders regions.
2) Data for Cyprus come from two schemes that partly differ in their regional coverage, Volunteer Common Birds Census (2006–2022) and Western Cyprus Common Bird Census (2006–2011). We combined the data from both schemes.
3) Data for France come from two schemes, the old (1989–2001) and the new one (2001–2021). We combined the data from both schemes.
4) Data for Germany were combined from schemes in former East and West Germany and also from the old scheme (Häufige Brutvögel alt, 1989–2010) and new scheme (Häufige Brutvögel neu, 2005–2021).
5) Data for Latvia come from three different schemes, two old ones (differ in their regional coverage, and cover the periods 1995–2006 and 2003–2006, respectively) and a new one (2005–2022). We combined the data from both schemes.
6) Data for Norway come from three schemes, Norsk Hekkefugltaksering, HFT (1996–2008), Terrestrisk overvåking, TOV-I (1996–2008) and Terrestrisk overvåking – Ekstensiv, TOV-E (2006–2022). Data from all schemes were combined.
7) Data for Sweden come from two schemes, the old (1975–2022) and the new one (1998–2022). We combined the data from both schemes.
Although we produce all species indices for the maximum time period (since the first year available), we publish only the European indices since the year 1980 at the earliest since the index is based on data from several countries – see the latest version of species indices and trends.
The species trends are produced for the maximum time period and shorter periods: since 1980, 1990, 2000, 2010, 2013 and 2018. We publish the long-term trends (the trends which starting year varies from 1980 to 1998) and the ten-year trends (the trends for last ten years, i.e. 2013–2022).