Methods 2011

Compiled by Petr Voří¹ek, Arco Van Strien, Willy Van Strien, Jana ©korpilová, Ian Burfield and Richard D. Gregory

What is new in 2011 data update?

  1. In 2011, the indices and trends for 145 common European species has been produced. This includes 8 new species compared to the last year (Bombycilla garrulus, Cygnus olor, Fulica atra, Gallinula chloropus, Numenius phaeopus, Pluvialis apricaria, Tringa glareola, Tringa ochropus).
  2. Number of countries contributing to the PECBMS increased with 3 new countries (Cyprus, Greece and Slovenia); altogether 25 European countries have provided data in 2011.
  3. New national schemes of the countries have been included in Spain and Norway. In Spain, data has been newly combined from 2 national surveys (Seguimiento de Aves Comunes Reproductoras en España, SACRE and Seguiment d'Ocells Comuns a Catalunya, SOCC), as well as in Norway data comes from 2 schemes (Norsk Hekkefugltaksering, HFT and Terrestrisk overvåking, TOV-I).
  4. Data from Cyprus also comes from 2 monitoring schemes (Volunteer Common Birds Census and Western Cyprus Common Bird Census).
  5. Norway has produced indices for one year shorter time period, i.e. since 1996; first year has been truncated due to much smaller sample size compared to the later years.
  6. Computation procedure as well as data quality control has not undergone any change, it has 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 (Voří¹ek et al., 2008) contains many information on methods. 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?

Production of European population trends and indices and indicators: an overview.


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 Geometric means - an example
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


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