The Summer Random Square Survey (SRSS) was established in 1991 to provide details on the birds that breed within the BOS survey area. Like the WRSS, this survey was established because this information was not beeing captured by our monthly recording system.

Each year 1km squares are chosen at random from each for the 12 10km squares of the BOS survey area, skipping squares that have already been surveyed. Observers are asked to make at least 3 site visits, 1 month apart, starting from late April. Participants record the activity of each bird seen, with the focus on evidence of potential breeding, along with the number of pairs observed. At the end of the survey observers are asked to estimate the total number of breeding pairs for each species. The estimate is reviewed and adjusted by the bird recorder to take account of the type of breeding evidence recorded, with emphasis given to direct breeding evidence.

The analysis method follows that of the WRSS. The first 3 years of results were averaged to produce a normalised index with a value of 100. For each subsequent year, a 3-year index value relative to this base figure is calculated. This provides a long term trend which shows the breeding trend status of common species across the BOS.

390 squares have been surveyed in the period 1991-2018, over 30% of the BOS.

The results of the survey for the first 30 years (1991-2011) can be read in our book Birds of the Heart of England.

The charts below show a summary of the surveys that have been conducted to date. Hover the mouse over the chart to see the specific annual values. Note that no survey was conducted in 2001 due to Foot & Mouth. The dashed lines show the linear trend.

The charts show that the society has managed to maintain the number of surveys performed per year. There has been a slight decline in the total number of breeding species recorded each year, though the number of species recorded per survey square has remained relatively constant.

Two maps are also provided, the 1st showing the squares surveyed to date along with the number of breeding species detected per 1km square as a tooltip (hover over a square to see). The 2nd 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.

Habitat Improvements at Bicester Wetland Reserve

In January 2019 the BOS received a grant from Thames Water and this enabled us to hire an 8 tonne excavator and driver for 3 full days of work on the reserve. Read more ...

New Zealand  -  Frances and Adrian Buckel

Frances and Adrian will be giving a presentation on their recent visit to New Zealand.  Read more ...

A survey of breeding birds, conducted using 3 visits over 3 months to a random 1km square. Read more ...

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