This page presents the current statistics on the BOS Monthly Records database. Note that since 2011 the database includes non-member records submitted via the BTO BirdTrack system. The charts show the summary for all records received, except where specifically noted.

Our electronic records start from 1982 and we have currently have almost 400,000 records (up to end 2020). The following charts present the annual status of the records, showing:

  • The number of records submitted by BOS members and from other sources (total). Note that duplicate sightings are omitted, i.e. the same bird seen at the same site on the same day.
  • The total number of species recorded each year. Statistics for the years prior to 1982 come from the Annual Reports. The dashed line is the trend. The dip for 1982-83 is in part due to the switch to the electronic recording system.
  • The number of grid squares records come from. Note that the BOS surveys 1200km2, so the charts show that recording comes from over 50% of the BOS area, a remarkably good rate of coverage
  • The number of named sites. Site names have been standardised since 2016 which allows us to better assess the number of sites visited.


In March 2020 the BTO launched their Chaffinch Appeal to raise funds to help them research why the UK population of Chaffinch is undergoing a significant decline. Read more ...

A survey where observers are each given a randomly selected 1km square and record all the species encountered and numbers of each for a minimum period of 2 hours between 9am and noon. Read more ...

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