Abstract from BTO Research Report No 300:

Noble, D. & Newson, S. (2002, published 2005)

Pilot work to assess bird occurrence and abundance on BBS squares within ESAs.

1. Because agri-environment schemes such as Environmentally Sensitive Areas (ESAs) and Arable Stewardship (AS) are designated and taken up on broad geographic scales, they are particularly suited for monitoring by broad-scale biodiversity survey programs. This report assesses the feasibility of using the BTO/RSPB/JNCC Breeding Bird Survey (BBS), which collects information on populations of breeding birds on more than 2000 UK sites annually, to monitor changes in populations of common breeding birds in ESAs in England and Wales.

2. Of 1782 BBS squares surveyed in England in 1999, 193 (11%) coincide with ESAs, and most of these (7% of total) include land under agreement. Analyses of species coverage show that between 48 and 59 species (on ESAs and ESA agreement land) occur at enough sites to assess population trends. In Wales, nine species could be monitored on ESAs. BBS routes are line transects, and by digitising the area up to 100m from the transect line, we were also able to assess species coverage on transect sections that coincided with ESA at a much higher resolution. This suggested a lower number of species (16) but further work would be required to develop analyses that take into account non-independence between transect sections.

3. Results show that a relatively large number of common species could be monitored on ESAs, and population trends reliably compared to population trends on random squares outside ESAs. However, more sites are required to effectively monitor some of the less abundant species, and there are noticeable gaps in coverage. One way of effectively monitoring a wider range of species and assessing population trends in some of the large northern and western ESAs currently poorly covered would be to develop a bolt-on to the BBS using the same methods. By using random selection of squares in target areas that match BTO regions, this would not affect the stratified random sampling design of the BBS. It might, however, be necessary to support field surveys because these tend to be areas with low volunteer availability.

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