BTO - Breeding Birds of the Wider Countryside: Discussion 4.3

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4.3	Ten-year trends and evidence for species recovery
If the status of species that have shown long-term declines were now improving, we would expect to find more positive trends in recent years compared with the earlier part of the time series. To examine this we list here the best change estimates over the most recent ten-year period for which we have data (1993–2003) for all of the declining species listed in the previous section of this report (Table 4.3).

Table 4.3 Best estimates of population change over the last 10 years (1993-2003) for all species identified as having long-term declines of greater than 25%.

See Help for information on what the categories mean

The 41 species listed include 17 from the red list, 19 declining species that are amber listed on account of population declines and five species that are not formally listed as declining. The table includes data on four species for which we do not report long-term trends but for which we can now report ten-year trends from BBS data. Ten species, Red-legged Partridge, Tree Sparrow, Dunnock, Nightingale, Song Thrush, Grey Wagtail, Whitethroat, Snipe, Grasshopper Warbler and Goldcrest show positive trends over the last ten years. The figure for Nightingale should be treated with caution as it is based on a small amount of data from CES sites. The steady increase in the red-listed Song Thrush since about 1997 is particularly encouraging, as are the positive trends for Dunnock, Grey Wagtail, Snipe and Grasshopper Warbler.

The rate of decline of 25% over 25 years that is used as a threshold for amber listing is equivalent to a decline of 10.9% over ten years (assuming both have the same annual rate of change). A further nine species, House Martin, Lapwing, Kestrel, Red Grouse, Reed Bunting, Mistle Thrush, Linnet, Bullfinch and Marsh Tit, have negative ten-year changes involving declines of less than 11%. None of the ten-year declines for these nine species are statistically significant. Thus our data suggest that the declines of these species appear to be levelling off, although there is as yet no clear indication of recovery.

Ten-year changes for the remaining 22 species in Table 4.3 indicate ongoing declines, with rates equivalent to at least 25% over 25 years. Five species, Lesser Redpoll, Willow Tit, Little Grebe, Wood Warbler and Lesser Spotted Woodpecker, have declined by more than 50% over the last ten years alone. The ongoing declines of so many of the species listed in Table 4.3 must be a cause of serious conservation concern.

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This report should be cited as: Baillie, S.R., Marchant, J.H., Crick, H.Q.P., Noble, D.G., Balmer, D.E., Coombes, R.H., Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. and Thewlis, R.M. (2006) Breeding Birds in the Wider Countryside: their conservation status 2005. BTO Research Report No. 435. BTO, Thetford. (http://www.bto.org/birdtrends) Pages maintained by Susan Waghorn and Iain Downie: Last updated 11 November, 2008