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 (2005–15 in all but three cases), for all of the declining species listed in Tables A1–A3 (previous section). For Lesser Spotted Woodpecker, Woodcock and Shelduck, the ten-year period for which data are tabulated is 1989–99.

Table B1 also includes four further species that are listed red or amber in BoCC4 because of recent breeding decline, and for which we can report ten-year trends, but which lacked annual monitoring data before 1994. These are Whinchat, Grasshopper Warbler and Wood Warbler (all red listed), and Swift (amber listed). 

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 -88 -91 -84 >50  
Greenfinch 10 CBC/BBS UK -59 -61 -57 >50  
Lesser Spotted Woodpecker 10 CBC to 1999 -51 -75 -22 >50 Small sample
Willow Tit 10 CBC/BBS UK -50 -62 -36 >50  
Little Owl 10 CBC/BBS UK -45 -53 -36 >25  
Cuckoo 10 CBC/BBS England -40 -44 -34 >25  
Woodcock 10 CBC to 1999 -40 -62 -11 >25 Small sample
Starling 10 CBC/BBS England -38 -41 -33 >25  
Swift 10 BBS UK -38 -42 -33 >25  
Grey Partridge 10 CBC/BBS UK -37 -44 -26 >25  
Marsh Tit 10 CBC/BBS UK -36 -45 -26 >25  
Lapwing 10 CBC/BBS UK -35 -42 -28 >25  
Redshank 10 WBS/WBBS waterways -35 -57 -8 >25  
House Martin 10 CBC/BBS England -33 -38 -28 >25  
Little Grebe 10 WBS/WBBS waterways -28 -46 2    
Kestrel 10 CBC/BBS England -27 -31 -21 >25  
Oystercatcher 10 WBS/WBBS waterways -26 -33 -17 >25  
Mistle Thrush 10 CBC/BBS UK -24 -28 -20    
Whinchat 10 BBS UK -22 -39 -5    
Common Sandpiper 10 WBS/WBBS waterways -21 -30 -10    
Tree Pipit 10 CBC/BBS England -19 -36 2    
Grey Wagtail 10 WBS/WBBS waterways -18 -29 -7    
Grasshopper Warbler 10 BBS UK -16 -37 6    
Red-legged Partridge 10 CBC/BBS UK -16 -21 -10    
Willow Warbler 10 CBC/BBS England -15 -21 -8    
Curlew 10 CBC/BBS England -14 -20 -7    
Sedge Warbler 10 CBC/BBS UK -13 -23 -2    
Snipe 10 WBS/WBBS waterways -13 -47 22    
Tawny Owl 10 CBC/BBS UK -13 -29 10    
Nightingale 10 CBC/BBS England -12 -37 25    
Skylark 10 CBC/BBS England -11 -15 -8    
Spotted Flycatcher 10 CBC/BBS UK -9 -25 9    
Wood Warbler 10 BBS UK -8 -40 36    
Corn Bunting 10 CBC/BBS UK -7 -21 13    
Garden Warbler 10 CBC/BBS UK -5 -14 5    
House Sparrow 10 CBC/BBS England -4 -8 0    
Yellowhammer 10 CBC/BBS UK -4 -8 0    
Song Thrush 10 CBC/BBS UK -1 -4 3    
Meadow Pipit 10 CBC/BBS England 0 -8 7    
Yellow Wagtail 10 CBC/BBS UK 0 -15 18    
Dipper 10 WBS/WBBS waterways 1 -10 13    
Dunnock 10 CBC/BBS UK 3 0 6    
Shelduck 10 CBC to 1999 3 -21 40    
Linnet 10 CBC/BBS England 5 -1 11    
Reed Bunting 10 CBC/BBS UK 8 0 17    
Sand Martin 10 WBS/WBBS waterways 12 -17 42    
Whitethroat 10 CBC/BBS UK 14 10 22    
Bullfinch 10 CBC/BBS UK 21 13 30    
Tree Sparrow 10 CBC/BBS England 41 15 68    
Lesser Redpoll 10 CBC/BBS England 47 5 89    

Species are listed in ascending order of population change. Thus the species with the steepest recent decline appear first. 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.

As indicated by their position at the top of Table B1, there is high confidence that the populations of Turtle DoveGreenfinch and Willow Tit have halved within just the last ten years, or even a shorter period. These are the only species in long-term decline that suffered a 50% fall during 2005–15 (but Lesser Spotted Woodpecker also met these criteria during the most recent ten-year period for which data are available). A further 12 species also raise alerts, having declined significantly by more than 25% (but less than 50%) in their most recent 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 raises serious conservation concern. A special case is Turtle Dove, for which the current rate of decline is not only very steep but also accelerating (88%, from 86% in last year's report, 84% in the 2015 report and 80% in the 2014 report).

The 25% threshold, which is used to define decreases over the 25-year period that are worthy of amber listing, is equivalent to a change of 10.9% over ten years, assuming a constant rate of change. Thus a decrease of 11% or greater listed in Table B1 indicates that these species (31 in all, including non-significant declines for Little Grebe, Tree Pipit, Grasshopper WarblerSnipeTawny Owl and Nightingale) are on course for new or renewed red or amber listing for breeding population decline.

A smaller decrease, or an increase, 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 significant population change, over the ten-year period are Spotted FlycatcherWood Warbler, Corn Bunting, Garden Warbler, House Sparrow, Yellowhammer, Song ThrushMeadow PipitYellow Wagtail, DipperShelduckLinnet, and Sand Martin.

Six species at the foot of the table show significant gains in population over the last ten years. The strong increase in Lesser Redpoll and Tree Sparrow numbers is very welcome but the upturns are coming from such a low level that numbers remain far below those of the mid 1970s, with the population trend graphs still showing little sign of clear recovery. Whitethroat numbers have increased steadily since the mid 1980s but again are still far below the level prior to their population crash in 1968/69. Bullfinch, Reed Bunting and Dunnock remain on the amber list, because their recent increases also represent only a small recovery from earlier losses.