About the Euring Databank index

This page provides information about the types of data that are included in the EURING databank (EDB) and about how the index was constructed.

Contents

• Euring Databank
• Content of the EDB index
• Types of data held in the EDB
• Maps of ringing and finding locations
• Summary tables
• Cautionary notes
• Colophon

Euring Databank

The Euring Databank collects copies of recovery records from bird ringing schemes throughout Europe. In the past, the emphasis was on birds ringed and later recovered dead. However, for many purposes such as survival analyses and studies of natal dispersal, recaptures or resightings of living birds are just as valuable. Recently, the number of live records has overtaken the number dead records.

Whereas some schemes send their data very regularly to the EDB, some other schemes have sent very large batches at long intervals. We estimate that 30 – 50 % of the records of dead birds recovered in the 1990’s are still missing.

Details of the coding scheme that is used for these data can be found here.

EURING welcomes applications to analyse data from the EDB. Details of how to apply for data can be found here.

Contents of the EDB index

This index was made in September 2003. At that moment there are just over 1,300,000 records of previously ringed birds that were recovered dead and there are almost 1,450,000 records of previously ringed birds that were recorded alive through retrapping or resighting. In this second group there are often multiple records per individual.

For 171 species (or subspecies) with > 500 recovery records there is a pair of maps showing on a scale of 5° by 5° blocks the numbers ringed and the numbers recovered in each block.

For all 161 species (or subspecies) with > 500 live recaptures/sightings their is a similar pair of maps.

Apart from the information per species there are four summary tables, two for the dead recoveries and two for the live recaptures. In each case there is one table giving the number of records per scheme per decade (live and dead). The tabulation per decade is based on the date of recovery or recapture.

All 235 species with > 100 live records together with the number of records per decade are tabulated here. Similarly, all 259 species (and subspecies) with > 100 dead recoveries are tabulated here.

Types of data held in the EDB

First of all, this is an index of the data in the EURING databank. The quality of these data is variable and for the purpose of making this index, only a very limited amount of checking has been performed (see below). The basic unit for constructing this index is the EDB record. One record describes one encounter with a bird together with the original marking details. Here, two types of records are considered:

1. Encounters with living birds, that have been identified through either recapture, or reading the ring or other unique marks from a distance. In these cases, there can be multiple records per individual (spoonbill is an example with many records per individual ). For each record of a live encounter, there is also a record with the ringing details (when where etc) of that individual. With multiple records on a single individual the ringing details are repeated for every encounter.
2. Encounters with dead birds. With each record there is a record with the ringing details of that individual. Cases of later reports of the same ring are ignored. There can thus be only one record of a bird recovered dead per individual.

Ringing data. are only included for individuals that are later encountered again, alive or dead. It is possible that an individual is encountered alive one or more times and is later encountered dead. In that case, the data for this individual will appear once on the map of ringing locations for birds later recovered dead and it will appear once on the map with the recovery locations. The same individual will appear as often as it has been reported alive on the map of recapture/resighting locations (at the same or different localities) but it will also appear on the map of ringing locations for birds later reported alive as often as it has been reported alive. One extreme example are the data for the Spoonbill for which there are many more resightings than individuals that have been ringed.

Maps of ringing and finding locations

The first step towards map construction was a tabulation of all records of a species in 5° by 5° blocks, both for the ringing and for the finding locations. Records where one or both locations were missing or were not known to within 10° have been entirely deleted. Thus, the number of records on both maps should be the same. To find a good balance between showing as much detail as possible and using a standardised representation, several different base maps have been used. We have chosen a log scale for representing the numbers of records on the maps.

Summary tables

Each pair of maps is accompanied by two tables: First there is a table that gives an overview of the number of records by decade. This tabulation is based on the year of recovery or recapture. All records referring to data before 1940 have been grouped. It should be noted again that these data are an index of the EDB. In particular the data for the 1990’s and beyond 2000 are expected to grow considerably when updates arrive from a number of schemes.

The second table gives an overview of the schemes that contributed most data. All schemes that contributed at least 500 records for that species are always listed. If less than 3 schemes contributed at least 500 records, all schemes that contributed at least 100 records have been listed. Thus, if fewer than 3 schemes are listed, there are fewer than 3 schemes that have contributed at least 100 records for that species. In this second table, there is an indicator for the time elapsed between ringing and recovery or resighting. For each record, the year of finding minus the year of ringing was calculated. The arithmetic mean of these differences is given per scheme. Low numbers indicate that a majority of the records refer to ringing and finding in the same year, high numbers refer to long times elapsed. Less than 500 out of 2.5 million records lead to a negative time elapsed or a time longer than 50 years. This indicates coding errors in the years and these data, have been disregarded, but the positions of these records have been retained within the data used to prepare the maps.

Cautionary notes

1. Name changes in schemes. This is an index of the data in the EURING databank. The names of schemes appear in the index as they are on the records in the EDB, which in turn corresponds to what is written on the rings. Several schemes have changed names when the countries changed names. For example LIK (Lithuania, Kaunas) was previously SUK (Soviet Union, Kaunas). Particular care should be taken with the German schemes where codes have been changed as a result of reunification. DEH (Hiddensee, Germany) used to be DDH (Hiddensee, East Germany), but all records have been recoded. DEW (Wilhelmshaven, Germany) used to be DFH (Helgoland, West Germany); most older records are coded as DFH, only the newer ones as DEW. The same is true for DER (Radolfzell, Germany), which used to be DFR (Radolfzell, West Germany).
2. Species and subspecies. For a number of species, there are separate codes for subspecies as well as a species code. The use of subspecies is not consistent among schemes and over time. In particular such problems arise with the Herring gull complex (Larus argentatus and Larus cachinnans) and with crows (Corvus corone corone and Corvus corone cornix). Birds from these groups may appear with either species or subspecies codes in the index.
3. Schemes and locations. Data are classified under schemes, which are the schemes that issued the ring. Within Europe, birds are normally ringed with rings of the scheme responsible for that area, but there have been exceptions and European rings have also been used in Africa and Asia. Thus, recovery data or recapture data in Africa can also arise from locally ringed birds. The EDB does not routinely collect records of birds ringed in Africa but some records involving the use of European rings in Africa have been included.
4. Updates. This index was made on all data in the EURING databank in September 2003. Since several steps in the process have not yet be automated, updates of maps and tables are not to be expected for several years.
5. Deleted records and totals. The purpose of this index is to give an overview of the data available in the EDB. Some incomplete records have been disregarded in some tabulations, but not in others. This may lead to small discrepancies in numbers between tables or between the information per species and the tables. The most common problem is incomplete spatial co-ordinates. The proportion of problematic records is in the order of 2 per 10 000.

*** EURING is particularly grateful to the Netherlands Institute for Ecological Research which hosted the EDB from 1977 to 2005.

The EDB is currently hosted by the British Trust for Ornithology.

COLOPHON

This index is the collaborative effort of several people:

Extractions from the EDB: Rinse Wassenaar, NIOO, Heteren NL
Selection and tabulations: Arie van Noordwijk, NIOO, Heteren NL
Map production: Andrea Ferri, Lara Marangoni & Fernando Spina, INFS, Bologna, Italy
Web page construction: Iain Downie, BTO, Thetford, UK
Discussions and Coordination: Arie van Noordwijk, Fernando Spina (INFS), David Thomson (NIOO), Stephen Baillie (BTO)

We are grateful to all of the Ringing Schemes who have contributed to the EDB, without whose efforts this invaluable European dataset would not be available. These schemes in turn are dependent on large numbers of ringers (most of whom are volunteers), birdwatchers and members of the public for the collection of data. We thank all of these people for their contributions.

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