The Winter Random Sqaure Survery (WRSS) as established in 1975 as a means to record the status of common species which are otherwise overlooked by our monthly recording system.

The WRSS is conducted in the last weekend of November and February, with results combined to produce the survey counts for that winter. Observers are allocated a 1km square at random from each of the 12 10km squares of the BOS survey area so that all parts of the survey area are covered. Each observer is asked to record each species seen and estimate the total number of each species over a period of 2-3 hours. In most years we are able to field multiple observers per 10km square, thus increasing coverage.

Squares are not re-surveyed until all surveyable squares have been surveyed. Squares are omitted where there is limited or restricted access. To date we have conducted 2 complete surveys, from 1975-2000 (1120 squares, 93%) and 2000-2016 (658 squares, 55%).

The results from the first 3 years (1976-1978) are averaged to produce an index for each species, one for abundance and one for distribution. From that time onwards, a 3-year rolling index is calculated, which shows the relative abundance and distribution change for each species.

This enables the BOS to analyse species trends over a 40 year period. In general the trends match national findings, but there are significant differences which allows the BOS to better understand species which are fairing better or worse within our survey area. We use this information to adjust the conservation targets on our reserves and when providing guidance to local planning.

The results of the survey can be read in our book Birds of the Heart of England.

The charts below provide a summary of the surveys performed to date and the number of species monitored. The dashed lines show the linear trend. The charts show that the monitoring has been very consistent, which is very good considering the small membership size of our society and the amount of territory to be covered. The number of species recorded per year has increased, which in part reflects the spread of species such as Buzzard, Red Kite and Raven which were once very rare in the area.

This report by the BOS reviews the population trends of Farmland and Woodland species in south central England compared to the whole of England for the 40 year period 1977 to 2016.  Read more ...

Bird Trends and Conservation needs - Mike Curnow and Mike Pollard

Mike Curnow has been working to produce a report on the bird trends in the BOS area compared to national trends.  Read more ...

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

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