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BLACKCAP Sylvia atricapilla
 
Conservation Listings Long term trend

Unlisted/Green
Biodiversity Steering Group Conservation Concern List

UK: Rapid increase
 
Status Summary
Blackcap abundance has increased consistently since the late 1970s, a trend shown across all habitats and in both the CBC and the CES indices. The increase can also be seen to be continuing in the last six years' BBS results, but its cause remains unknown. There have been no clear accompanying trends in productivity. The trend towards earlier laying can be explained by recent climate change (Crick & Sparks 1999).
 
 
Table of population changes for Blackcap
Source Period
(yrs)
Years Plots
(n)
Change
(%)
Lower
limit
Upper
limit
Alert Comment
CBC all habitats 30 1968-1998 155 106 71 153    
  25 1973-1998 163 100 76 140    
  10 1988-1998 174 44 37 52    
  5 1993-1998 184 34 28 42    
CBC farmland 30 1968-1998 56 143 . .    
  25 1973-1998 58 107 . .    
  10 1988-1998 67 55 . .    
  5 1993-1998 69 48 . .    
CBC woodland 30 1968-1998 71 54 . .    
  25 1973-1998 77 67 . .    
  10 1988-1998 86 38 . .    
  5 1993-1998 92 28 . .    
CES adults 14 1984-1998 83 39 . .    
  10 1988-1998 95 38 . .    
  5 1993-1998 104 31 . .    
CES juveniles 14 1984-1998 84 32 . .    
  10 1988-1998 96 40 . .    
  5 1993-1998 107 16 . .    
BBS UK 5 1994-1999 971 50 41 60    
BBS England 5 1994-1999 856 47 38 56    
BBS Scotland 5 1994-1999 26 92 25 196   Small sample
BBS Wales 5 1994-1999 76 59 25 102    
The Breeding Bird Survey is jointly funded by BTO, JNCC and RSPB
 
 
Table of productivity information
Variable Period
(yrs)
Years Mean
annual
sample
Trend Predicted
in first year
Predicted
in last year
Change Comment
Clutch size 30 1968-1998 35 None        
Brood size 30 1968-1998 42 None        
Daily failure rate (eggs) 30 1968-1998 46 None        
Daily failure rate (chicks) 30 1968-1998 35 Curvilinear 0.0248 nests/day 0.0309 nests/day 0.0061 nests/day  
Laying date 30 1968-1998 36 Curvilinear day 139 day 133 -6 days  
Percentage juveniles (CES) 14 1984-1998 91 Smoothed trend 109 productivity index 100 productivity index -8%  
Percentage juveniles (CES) 10 1988-1998 103 Smoothed trend 105 productivity index 100 productivity index -5%  
Percentage juveniles (CES) 5 1993-1998 113 Smoothed trend 117 productivity index 100 productivity index -14%  
 
   


The report should be cited as: Baillie, S.R., Crick, H.Q.P., Balmer, D.E., Bashford, R.I., Beaven, L.P., Freeman, S.N., Marchant, J.H., Noble, D.G., Raven, M.J., Siriwardena, G.M., Thewlis, R. and Wernham, C.V. (2001) Breeding Birds in the Wider Countryside: their conservation status 2000. BTO Research Report No. 252. BTO, Thetford. (http://www.bto.org/birdtrends)




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