Occurrence dataset Registered February 21, 2024

    Common bird monitoring scheme in Bulgaria

    Hristov I • Stoychev S • Spasov S • Popgeorgiev G

    Description

    The Common bird monitoring scheme is developed by the Bulgarian Society for the Protection of Birds. The data are used to produce trends of common birds in the country which are published in nine yearly reports. These reports contain not only individual species trends but also habitat indices like the Farmland bird index and Forest Bird Index. The first year of publication is 2007 which contains the first assessment of the species trends for the period 2005-2007.

    Data are submitted annually to the Pan European Common Bird Monitoring Scheme administration to produce European wide indices and species trends. These trends and indices are delivered to the European Commission and Eurostat for decision-making.

    The current data set presents data for each individual survey plot visited in the period mentioned below.

    Geographic scope

    Description

    Bulgaria

    Latitude
    From 41.458 to 44.113
    Longitude
    From 22.514 to 28.377

    Temporal scope

    range
    May 03, 2004 - June 20, 2023

    Taxonomic scope

    Description

    N/A

    Coverage
    Aves

    Methodology

    Sampling

    The field survey methodology includes selection of two transects oriented N-S or E-W depending on the terrain. Transects are recommended to be 500m apart from each other and 250 m from the sides of the square. If the terrain does not allow, it is possible to use data from only one transect to include the square into the surveys.
    The sampling effort includes two transects across the square, 1 km long each. If the terrain does not allow surveying of 2 transects, the data from survey plot can be considered even with only one transect. Each square has one person responsible for it.
    Once the transects are selected, the observer should conduct two visits each year in approximately the same time. First (early) visit is in the period April 15th to May 15th and second (late) visit in the period May 16th – June 15th. Mountainous survey plots may have later dates for visits.

    Study extent

    The survey methodology description includes two sections: selection of survey plots and field surveying. The selection of survey plots is semi-stratified. In each 10 km UTM square in the country are randomly selected 5 squares 1x1 km each. From these squares, volunteers can choose a 1x1 km square depending upon its proximity to their homes.

    Method steps
    1. During survey work, observers record each individual bird. The distance to the birds is entered in four categories 1 (0-25m), 2 (25-100m), 3 (>100 m), F – for birds flying over. Other than bird data, observers are asked to collect data for the beginning and the end of the survey. The database calculates the number of visits per year of each survey plot in relation to the date of visit.

    2. The data collected in the period 2004 - 2016, are georeferenced in the centroid of the MGRS UTM 1 km.
      Data after 2016 are collected with a mobile app for Android developed specifically for the purpose (SmartBirds Pro).

    Metrics

    Contacts

    • Iordan Hristov

      Originator
      Editor
      Administrative point of contact
      Organization
      Bulgarian Society for the Protection of Birds
      Position
      Monitoring officer
      Address
      Yavorov quarter, Bl. 71, Entr. 4, app. 1
      Roles
      Originator
      Editor
      Administrative point of contact
      Email
      Phone
    • Stoycho Stoychev

      Originator
      Administrative point of contact
      Organization
      Bulgarian Society for the Protection of Birds
      Position
      Conservation director
      Address
      Yavorov quarter, Bl. 71, Entr. 4, app. 1
      Roles
      Originator
      Administrative point of contact
      Email
      Phone
    • Svetoslav Spasov

      Originator
      Organization
      Bulgarian Society for the Protection of Birds
      Position
      Project manager
      Address
      Yavorov quarter, Bl. 71, Entr. 4, app. 1
      Roles
      Originator
      Email
      Phone
    • Georgi Popgeorgiev

      Originator
      Metadata author
      Administrative point of contact
      Organization
      Bulgarian Society for the Protection of Birds
      Position
      DB manager
      Address
      Plovdiv
      Roles
      Originator
      Metadata author
      Administrative point of contact
      Email
      Phone
      User ID

    GBIF registration

    Registration date
    February 21, 2024
    Metadata last modified
    February 22, 2024
    Publication date
    February 22, 2024
    Hosted by
    GBIF Secretariat
    Installation
    GBIF Europe and Central Asia
    Endpoints
    Darwin Core Archive
    EML
    Preferred identifier
    10.15468/t6scvp
    Alternative identifiers

    Citation

    Hristov I, Stoychev S, Spasov S, Popgeorgiev G (2024). Common bird monitoring scheme in Bulgaria. Version 1.4. Bulgarian Society for the Protection of Birds. Occurrence dataset https://doi.org/10.15468/t6scvp accessed via GBIF.org on 2025-08-04.