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% of the BOS) and 2000-2016 (658 squares, 55%). A third period of surveys started in November 2016. Interestingly, we have found that the average number of species recorded per survey square has not changed in the 3 periods, indicating that the species richness has not changed. However, it appears that the abundance has now started to decline, i.e. the total number of birds seen in the surveys is now lower than it used to be.

The results from the first 3 years of surveys (1975-1977) 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 since 1975. 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 and the report Bird Trends in 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. Overall, the total 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, though the number of species per square has remained almost constant at 25.

The following two maps summarise the winter survey results in the current survey cycle which started in November 2016. The map on the left shows the number species observed in each WRSS survey square - the larger the square, the greater the number of species recorded. Hover the mouse over a square to see the details. The second map shows the number of squares surveyed per 10km square. We try and ensure an even coverage across the 10km squares, but this is subject to observer availability so some parts of our area have not been surveyed to the same extent.

The BOS conducted a survey of Yellowhammers in the first 2 weeks of July 2018 to determine their population abundance, distribution and breeding status. All members and the general public were invited to participate. Read more ...

The AGM and Quiz.


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