Common bird monitoring scheme in Bulgaria

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.

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.

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).

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1. Aves
   rank: kingdom

Bulgaria