Every year two full-day counts are held across the entire BOS area. The first is held in early January from 08:00-16:00 and the second in early May for 12 hours. The surveys complement the WRSS and SRSS in providing a count of the total number of species across the entire region, not just specific sites.
The surveys are conducted as a team, with the aim to field at least one team per 100-km square. For observers, the incentive is to beat the par species count of previous years, with awards given to the team most over par. A second award is provided for finding the "star" species of the day.
The comparitive results over the years supplements the findings from the other surveys, giving us confidence in the survey results.