Methods 2018

Compiled by Jana Škorpilová, Petr Voříšek, Arco Van Strien, Willy Van Strien, Ian Burfield and Richard D. Gregory

What is new in 2018 data update?

  • In 2018, the indices and trends for 170 common European species has been produced based on the data from 28 countries. The number of species published and the countries contributing to the PECBMS in 2018 remained the same as the last year.
  • Indices of Luxembourg, Italy and Portugal have not been updated this year, older indices up to the year 2012 (Luxembourg), up to 2014 (Portugal) or up to 2015 (Italy) have been used instead.
  • All indices from Estonia and indices for several species from Denmark has been shorten compared to the last update. Estonia now starts one year later (from 1984), and some species from Denmark start now at early 80s (while the others are from 1976).
  • The species indices are presented in graphs including their lower and upper confidence limits for the time periods from 1980-onwards. All such data are also available for download in a table.
  • Two species (Oenanthe cypriaca and Sylvia melanothorax) haven´t been included in all common bird indicators for Europe and EU as they are endemic species for Cyprus and not common for whole Europe. Consequently, only 168 species are included in common bird indicators. Number of species included in common farmland and common forest bird indicators for Europe and EU remained unchanged (39 farmland species and 34 forest species).
  • In this update, we again used a tool to calculate multi-species indices (indicators) developed in Statistics Netherlands. The tool produces the same outputs as in the previous updates of the indicators and also the smoothed values with confidence intervals. For more details on the tool and statistical procedure please check Soldaat, L.L., J. Pannekoek, R.J.T. Verweij, C.A.M. van Turnhout & A.J. van Strien. 2017. A Monte Carlo method to account for sampling error in multi-species indicators. Ecological Indicators.
  • The smoothed indicators and their lower and upper confidence limits for the time periods from 1980-onwards are presented in graphs at the website. All such data for the time periods from 1980-onwards and 1990-onwards are available for download in a table .
  • Beside this, computation procedure, data quality control and presented indices, trends and indicators have not undergone any change, all have been kept consistent with last year data update.

The methods that PECBMS uses to produce species population trends and indices and wild bird indicators have been described in several scientific papers. The internationally accepted standards according to which national monitoring schemes, being the data source for PECBMS, are organized, are available in textbooks and scientific papers. Also, the PECBMS Best Practice Guide contains many information on methods (electronic version; 14 MB, download here). But as a consequence, the information on methods is scattered. On this web page we bring together all this information to facilitate the understanding of data collection, and analysis procedures. The text in Methods proceeds step by step, from national bird monitoring schemes to European multispecies bird indicators, and ends with a chapter on quality control performed at each step.

The most important questions that have been asked about PECBMS methods and interpretation of results are answered on a separate page: Questions and Answers.

Information on the aims & structure of PECBMS, the results, the use, some history and future plans is given on the page What is PECBMS?


1. National species indices and trends

1.1 Counting birds
Box Field methods
Box Detectability
Box Selection of sample plots
1.2 Production of national indices and trends
Box Missing values I
Box Trend interpretation and classification

2. Supranational species indices and trends

2.1. Delivery of national data to PECBMS coordination unit
Box Data checks
Box Participating countries
2.2. Combining national data into supranational outputs
Box Missing values II
2.3. Types of supranational results that PECBMS produces

3. Multispecies indicators

Box Species selection and classification

4. Quality control

4.1. On the national level
4.2. At delivery to PECBMS
4.3. For supranational indices and trends
4.4. For multispecies indicators

5. References and further reading