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Ten-year trends and evidence of species recovery

If the status of species that have shown long-term declines were now improving, we would expect to find trends to be more positive in recent years than in the earlier part of the time series. To examine this, we list in Table B1 the best change estimates over the most recent ten-year period for which we have data (1999–2009), for all of the declining species listed in Tables A1–A3 (here).
The table also includes seven further species which are listed in BoCC3 because of recent breeding decline, for which we can report ten-year trends but which lack monitoring series covering longer periods. These are Grasshopper Warbler and Wood Warbler (both red listed), and Red Grouse, Swift, Nightingale, Whinchat, and Pied Flycatcher (all amber listed).

Species are listed in ascending order of population change. Thus the species with the steepest recent decline appear first, followed by those with shallower change. Towards the foot of the table are species that remain in long-term decline but have shown partial recovery of those losses during the recent ten-year period. For Lesser Spotted Woodpecker and for Woodcock, both now too scarce for annual monitoring to continue, the ten-year period for which data are tabulated is 1989–99.

The 44 species listed include 21 from the red list, 18 declining species that are amber listed on account of population declines and five species (Snipe, Woodcock, Little Owl, Dipper and Tawny Owl) whose declines, for reasons explained here, are not recognised by either red or amber listing. Of these, Snipe and Woodcock are already amber listed because they are Species of European Conservation Concern (SPEC category 3) through their moderate declines on the European scale (BiE04).

 

Table B1 Ten-year trends for species that have shown long-term declines

Species Period
(yrs)
Source Change
(%)
Lower
limit
Upper
limit
Alert Comment
Turtle Dove 10 CBC/BBS UK -68 -73 -62 >50  
Willow Tit 10 CBC/BBS UK -65 -76 -56 >50  
Nightingale 10 BBS England -59 -70 -41 >50  
Cuckoo 10 CBC/BBS England -51 -54 -47 >50  
Lesser Spotted Woodpecker 10 CBC to 1999 -51 -75 -22 >50 Small sample
Redshank 10 WBS/WBBS waterways -51 -65 -36 >50  
Whinchat 10 BBS UK -46 -60 -33 >25  
Starling 10 CBC/BBS England -44 -46 -39 >25  
Wood Warbler 10 BBS UK -43 -61 -21 >25  
Yellow Wagtail 10 CBC/BBS UK -42 -52 -31 >25  
Pied Flycatcher 10 BBS UK -42 -58 -24 >25  
Snipe 10 WBS/WBBS waterways -40 -67 -12 >25  
Woodcock 10 CBC to 1999 -40 -62 -11 >25 Small sample
Spotted Flycatcher 10 CBC/BBS UK -38 -52 -14 >25  
Grey Partridge 10 CBC/BBS UK -36 -46 -27 >25  
Tree Pipit 10 CBC/BBS England -36 -52 -20 >25  
Little Owl 10 CBC/BBS UK -35 -46 -24 >25  
Willow Warbler 10 CBC/BBS England -27 -32 -23 >25  
Mistle Thrush 10 CBC/BBS UK -25 -29 -20    
Tawny Owl 10 CBC/BBS UK -25 -38 -12    
Swift 10 BBS UK -25 -32 -18    
Curlew 10 CBC/BBS England -24 -31 -17    
Dipper 10 WBS/WBBS waterways -22 -32 -8    
Marsh Tit 10 CBC/BBS UK -22 -34 -10    
Lesser Redpoll 10 CBC/BBS England -20 -56 22    
Linnet 10 CBC/BBS England -20 -25 -13    
Common Sandpiper 10 WBS/WBBS waterways -19 -31 -8    
Red Grouse 10 BBS UK -17 -30 -3    
Corn Bunting 10 CBC/BBS UK -15 -33 4    
House Martin 10 CBC/BBS England -14 -22 -7    
Skylark 10 CBC/BBS England -11 -14 -7    
Meadow Pipit 10 CBC/BBS England -9 -18 5    
Yellowhammer 10 CBC/BBS UK -9 -14 -4    
House Sparrow 10 CBC/BBS England -7 -12 -2    
Lapwing 10 CBC/BBS UK -6 -17 6    
Grey Wagtail 10 WBS/WBBS waterways 1 -9 13    
Grasshopper Warbler 10 BBS UK 4 -20 22    
Little Grebe 10 WBS/WBBS waterways 6 -28 59    
Song Thrush 10 CBC/BBS UK 14 9 19    
Whitethroat 10 CBC/BBS UK 15 9 21    
Bullfinch 10 CBC/BBS UK 16 5 24    
Dunnock 10 CBC/BBS UK 17 13 20    
Reed Bunting 10 CBC/BBS UK 32 18 47    
Tree Sparrow 10 CBC/BBS England 35 7 66    

See Birds of Conservation Concern pages for information on red and amber criteria

 

As indicated at the top of Table B1, there is high confidence that the populations of both Willow Tit and Turtle Dove have halved in the last ten years alone (1998–2008). In all, six species crossed the threshold of a 50% decline during the ten years. A further 12 also continue to raise alerts, having declined significantly by more than 25% (but less than 50%) in this ten-year period. All these declines compound earlier losses for these species. The ongoing declines of so many of the species listed in Table B1 must be a cause of serious conservation concern. Two (Lesser Spotted Woodpecker and Woodcock) have provided very little monitoring data during the most recent ten-year period, their populations having dropped to so low a level.

The 25% threshold which is used to define decreases over the 25-year period that are worthy of amber listing equates to a change of 10.9% over ten years, assuming a constant rate of change. Rounding this to 11%, a decrease of 11% or greater indicates that, on the last ten years' results, the species is still on course for red or amber listing. A more positive change than -11% indicates that the population decline may be easing off. Species that have declined in the longer term but with losses smaller than 11%, or with no measurable population change, over the ten-year period are Meadow PipitYellowhammerHouse SparrowLapwingGrey WagtailGrasshopper Warbler, and Little Grebe


Six species at the foot of the table show clear positive trends over the last ten years. Despite its recent increase, the long-term decline of Whitethroat was recognised in 2009 by the move of the species from the green to the amber list. Whitethroat numbers have increased steadily since the mid 1980s but are still far below the population level prior to their population crash in 1968/69 . Tree Sparrow and Song Thrush remain on the red list, and Dunnock and Bullfinch on the amber list, because their recent increases also represent only a small recovery from earlier losses. The increase in Tree Sparrow numbers is very welcome but is coming from such a low level that numbers remain far below those of the mid 1970s, with the population trend graph still showing little sign of a clear recovery. Because of its recent steep upturn, however, Reed Bunting was moved in 2009 from the red to the amber list. 

 

This report should be cited as: Baillie, S.R., Marchant, J.H., Leech, D.I., Renwick, A.R., Eglington, S.M., Joys, A.C., Noble, D.G., Barimore, C., Conway, G.J., Downie, I.S., Risely, K. & Robinson, R.A. (2012) BirdTrends 2011. BTO Research Report No. 609. BTO, Thetford. http://www.bto.org/birdtrends