The British Trust for Ornithology
SONG THRUSH
Turdus philomelos
Conservation listings

Table 3/Red (>=50% Population decline)
Biodiversity Steering Group Priority Species Group

Long-term trend
UK: Rapid decline
Farmland: Rapid decline
Woodland: Moderate decline
Status summary
The CBC shows a rapid decline in Song Thrush abundance that began in the mid-1970s. The latter half of this decline can also be seen in the CES index. CES productivity shows no clear temporal trend and NRS data indicate that breeding performance has improved during this period (failure rates at the egg stage (16 days, comprising 13 days incubation + 3 days laying) decreased from 50% in 1981 to 40% in 1999); changes in survival of juveniles in their first year of life probably drove the decline (Thomson et al. 1997, Siriwardena et al. 1998a). Recent CBC and BBS trends suggest that the decline has levelled off. Decreasing Song Thrush abundance has been linked to agricultural intensification (Fuller et al. 1995), but woodland-specific factors such as drainage and the depletion of the shrub layer may also be implicated (Vanhinsbergh et al. 2001).
 
 
Table of population changes for Song Thrush
Source Period
(yrs)
Years Plots
(n)
Change
(%)
Lower
limit
Upper
limit
Alert Comment
CBC all habitats 31 1968-1999 204 -57 -64 -51 >50  
  25 1974-1999 208 -53 -59 -46 >50  
  10 1989-1999 187 -4 -13 6    
  5 1994-1999 189 6 -2 14    
CBC farmland 31 1968-1999 85 -69 -76 -60 >50  
  25 1974-1999 82 -66 -73 -57 >50  
  10 1989-1999 76 -12 -24 1    
  5 1994-1999 74 4 -8 14    
CBC woodland 31 1968-1999 81 -46 -58 -30 >25  
  25 1974-1999 87 -40 -52 -20 >25  
  10 1989-1999 91 6 -10 24    
  5 1994-1999 95 13 4 24    
CES adults 15 1984-1999 81 -40 . . [>25*]  
  10 1989-1999 93 -31 . . [>25*]  
  5 1994-1999 96 -19 . .    
CES juveniles 15 1984-1999 65 -53 . . [>50*]  
  10 1989-1999 74 -21 . .    
  5 1994-1999 77 -15 . .    
BBS UK 6 1994-2000 1371 12 6 18    
BBS England 6 1994-2000 1067 7 1 13    
BBS Scotland 6 1994-2000 131 18 -3 44    
BBS Wales 6 1994-2000 119 34 15 57    
BBS N.Ireland 6 1994-2000 46 27 -11 83   Small sample
The Breeding Bird Survey is jointly funded by BTO, JNCC and RSPB
 
 
Table of productivity information for Song Thrush
Variable Period
(yrs)
Years Mean
annual
sample
Trend Predicted
in first year
Predicted
in last year
Change Comment
Clutch size 31 1968-1999 178 None        
Brood size 31 1968-1999 197 None        
Daily failure rate (eggs) 18 1981-1999 360 Linear decline 0.0421 nests/day 0.0317 nests/day -0.0104 nests/day  
Daily failure rate (chicks) 18 1981-1999 267 Linear decline 0.0247 nests/day 0.0189 nests/day -0.0058 nests/day  
Laying date 31 1968-1999 206 None        
Percentage juveniles (CES) 15 1984-1999 87 Smoothed trend 127 productivity index 100 productivity index -21%  
Percentage juveniles (CES) 10 1989-1999 101 Smoothed trend 81 productivity index 100 productivity index 23%  
Percentage juveniles (CES) 5 1994-1999 106 Smoothed trend 91 productivity index 100 productivity index 10%  
 




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This report should be cited as:
Baillie, S.R., Crick, H.Q.P., Balmer, D.E., Beaven, L.P., Downie, I.S., Freeman, S.N., Leech, D.I., Marchant, J.H.,
Noble, D.G., Raven, M.J., Simpkin, A.P., Thewlis, R.M. and Wernham, C.V.
(2002) Breeding Birds in the Wider
Countryside: their conservation status 2001. BTO Research Report No. 278. BTO, Thetford. (http://www.bto.org/birdtrends)

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