Contents: 2.1. Delivery of national data to PECBMS coordination unitCoordinators of national monitoring schemes deliver their national data to the PECBMS coordination unit annually. For information on data and contributing countries see Box Participating countries. 2.2. Combining national data into supranational
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
The data delivered are: the national yearly indices per species, the all-sites yearly totals (= the sum of birds counted across all sites per year) and their standard errors, and the covariances between the yearly figures.
Specifically, national coordinators deliver two files per species - so called out and ocv files (see paper by Pannekoek & Van Strien, 2001 or also see website of Statistics Netherlands) - both produced by TRIM when calculating species indices at the national level. These TRIM output files are accompanied by a species list and by comments indicating any potential problems in the data. These comments are taken into account in further data analysis.
National data are checked for their quality using quantitative criteria (see Box Data checks).
outputsA method has been developed to produce supranational yearly totals and their standard errors across countries by combining the national data. The method takes into account the differences in population sizes per country, as well as the differences in field methods and in the numbers of sites and years covered by the national schemes. Instead of deriving the standard errors in the usual statistical way from count data and model fit, standard errors (and the year-year covariances) that resulted from the calculation of the all-sites totals per country were applied. The results are similar to those that would be produced when the raw data are being used (Van Strien et al, 2001).
To produce supranational indices, the national all-sites totals per species as assessed in the national monitoring schemes are combined. A weighting factor is introduced to adjust for differences in national population sizes, to make sure that a change in a larger national population has an accordingly greater impact on the overall trend than a change in a smaller population. The weighting factor is calculated as the national population size derived from BirdLife International (2004) in 1999-2000 divided by the average of the all-sites totals for 1999-2001. This weighting factor is applied to all other years of the scheme. By this weighting, the yearly scheme totals are converted into yearly national population sizes.
The national European monitoring schemes have started in different years, leading to missing national all-sites totals. An adapted version of TRIM is used to estimate the missing country totals, in a way equivalent to imputing missing counts for particular sites within a country. After these weightings and imputation steps, the national totals are summed up to European totals.
European species indices for a species are computed if data are available from countries which together host at least 50% of the ´PECBMS European´ population of that species. ´PECBMS Europe´ is EU 27 + Norway and Switzerland and consists of those countries which already deliver their data to PECBMS or are supposed to do so in the near future: Austria, Belgium, Bulgaria, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Italy, Latvia, Lithuania, Netherlands, Norway, Poland, Portugal, Republic of Ireland, Romania, Slovakia, Spain, Sweden, Switzerland, United Kingdom.
However, some parts of these countries (states) were excluded, mainly because of their far distance to the mainland of Europe: Faroe Islands and Greenland, Svalbard, Azores, Madeira, Canary Islands, Gibraltar.
Population species trends (multiplicative slopes) are computed and classified in the same way as at the national level.
Types of supranational results that PECBMS produces:
Species indices and trends are produced for Europe and its regions (Central & East, North, South and West Europe) and for EU and its regions: New (since 2004) and Old EU Members States).
The species indices are always computed for 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 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 22 countries, their start years and region that each country belongs to:
Country/region Region(group of countries) First year Last year Austria WE 1998 2008 Belgium-Brussels1) WE 1992 2008 Belgium-Wallonia1) WE 1990 2008 Bulgaria SEE 2005 2008 Czech Republic CEE 1982 2008 Denmark WE 1976 2008 Estonia CEE 1983 2006 Finland NE 1975 2008 France2) SE 1989 2008 Germany East3) CEE 1991 2008 Germany West3) WE 1989 2008 Hungary CEE 1999 2008 Italy SE 2000 2007 Latvia4) CEE 1995 2008 Netherlands WE 1984 2008 Norway NE 1995 2008 Poland CEE 2000 2008 Portugal SE 2004 2008 Republic of Ireland WE 1998 2008 Slovakia CEE 2005 2008 Spain SE 1998 2008 Sweden5) NE 1975 2008 Switzerland WE 1999 2008 United Kingdom WE 1966 2008
WE - West Europe
NE - North Europe
SE - South Europe
SEE - Southeast Europe
CEE - Central & East Europe
First year - 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.
1) Data for Belgium were combined from Wallonia and Brussels regions.
2) Data in France come from two schemes, old (1989-2001) and new one (2001-2008). Data from both schemes were combined.
3) Data for Germany were combined from schemes in former East and West Germany.
4) 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 (2005-2008). Data from all schemes were combined.
5) Data for Sweden come from two schemes, old (1975-2008) and new one (1998-2008). Data from both schemes were combined.
However, we publish the European indices since the year 1980 at the earliest since when the index is based on data from several countries.
The species trends are produced for the maximum time period and for shorter periods as well: since 1980, 1990, 1995, 2000, and last 10 and 5 years. For simplicity only, the trends since 1980 and 1990 are published.
2.1. Delivery of national data to PECBMS coordination unitCoordinators of national monitoring schemes deliver their national data to the PECBMS coordination unit annually. For information on data and contributing countries see Box Participating countries.
2.2. Combining national data into supranational