Abstract from BTO Research Report No 368:

Newson, S.E., Noble, D.G. & Eaton, M.A. (2006)

Preliminary BBS-based habitat-specific indicators for wild bird populations: 1994-2002
ISBN: 1-904870-83-X

Executive summary

1. Data from the Breeding Bird Survey were analyzed at the transect section level of resolution to generate series of habitat-specific annual indices for each species. The results presented here are derived from all species that occurred in a given habitat in at least 20 squares per year.

2. A habitat-specific farmland bird indicator (based on farmland species on farmland) was almost identical to the QOL farmland bird indicator (based on the same 19 farmland species in all habitats) – both declining by 5% between 1994 and 2002. This was also true for farmland specialists (declining by 7 %) and farmland generalists (declining by 1 %).

3. An alternative indicator (based on farmland-specific trends for all species recorded on farmland) differed from the versions above, exhibiting a positive trend of between 6 % and 7 %.

4. Trends for farmland species in semi-natural grassland dominated habitats were slightly more negative than those for those species on farmland.

5. A habitat-specific woodland indicator (based on woodland species in woodland) was quite similar (declining by 5 %) to the QOL woodland bird indicator based on woodland bird trends in all habitats (which declined by 7 %). Woodland specialists declined slightly more in ‘all’ habitats (-10 %) than in woodland (-7 %).

6. The alternative indicator (based on woodland-specific trends for all species recorded in woodland) showed less of a decline (-1 %), exactly the same as for woodland generalists in woodland, and in all habitats.

7. Urban-specific indicators based on trends of (i) common town and garden species, (ii) farmland species, and (iii) woodland species, in human-dominated landscapes were generally positive, except for farmland specialists.

8. Waterbody-specific indicators based on trends of ‘water and wetland’ species (defined jointly in the England Biodiversity Strategy) were less positive (+ 10 %) solely on wetland sites than across all habitats (+ 22 %).

9. Upland indicators based on trends of upland species surveyed in heath and bog habitats showed a 1 % decline, whereas trends for the same upland species across all habitats showed a 4 % increase.

10. Trends for woodland species, particularly for woodland specialists, in scrubland were more positive than in woodland, but were based on a smaller suite of more common species. Most woodland species show similar trends for woodland and scrubland habitats.

11. The habitat-specific indicators produced by these methods show that both the habitat in which birds were recorded and overall features of the species are important. Habitat-specific indicators were very similar to the QOL indicators for those species groups, but indicators based on all species in farmland or woodland habitat were more difficult to interpret. For the latter, the pattern for all species in woodland habitats was similar to those for woodland generalists in woodland or all habitats, but the pattern for all species in farmland habitats was significantly more positive than other farmland indicators.

12. The all species habitat-specific indicators presented herein are novel, with examples presented for two habitats only. They suggest that in some cases this approach may produce considerably different indicator trends to those of the existing indicators for the same habitats.

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