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BTO Blueline
REED WARBLER
Acrocephalus scirpaceus
Reed Warbler © Graham Austin
Conservation listings
Europe: no SPEC category (concentrated in Europe, conservation status favourable)
UK: green
Long-term trend
UK: shallow decline since 1983 (but moderate increase at low-density sites)
Distribution maps
Maps and statistics from British and Irish
atlases can be viewed here.
Status summary
This species has an unusually patchy distribution, with very high densities in Phragmites reedbeds, where numbers are very hard to census. Because of this, CES, which has many sites in reedbeds, may be a better measure of population change than either CBC/BBS or WBS, where the species is encountered mainly at low density or in linear habitats. CES shows a decline from 1983 until the early 1990s, followed by a partial recovery. Both CBC/BBS and WBS show progressive moderate increases, perhaps linked to increasingly sensitive management of small and linear wetland sites. NRS breeding performance has improved slightly, and a small improvement is apparent in CES productivity. The trend towards earlier laying can be partly explained by recent climate change (Crick & Sparks 1999).
 
CES adult abundance graph
 
Table of population changes for Reed Warbler
Source Period
(yrs)		 Years Plots
(n)		 Change
(%)		 Lower
limit		 Upper
limit		 Alert Comment
CBC/BBS UK 35 1967-2002 43 89 27 260    
  25 1977-2002 53 88 27 221    
  10 1992-2002 95 48 20 81    
  5 1997-2002 120 9 -9 31    
CBC/BBS England 35 1967-2002 41 64 10 254    
  25 1977-2002 50 62 19 142    
  10 1992-2002 91 40 14 74    
  5 1997-2002 115 6 -9 23    
WBS waterways 21 1981-2002 22 60 15 116    
  10 1992-2002 27 44 9 74    
  5 1997-2002 28 21 -2 43    
CES adults 18 1984-2002 52 -20 . .    
  10 1992-2002 62 9 . .    
  5 1997-2002 62 -8 . .    
CES juveniles 18 1984-2002 53 -11 . .    
  10 1992-2002 65 14 . .    
  5 1997-2002 65 -2 . .    
BBS UK 9 1994-2003 87 10 -10 35    
BBS England 9 1994-2003 83 6 -14 30    
BBS acknowledgement
 
CBC/BBS UK graph
CBC/BBS England graph
WBS UK graph
CES juvenile abundance graph
BBS UK graph
BBS England graph
 
Table of productivity information for Reed Warbler
Variable Period
(yrs)		 Years Mean
annual
sample		 Trend Predicted
in first year		 Predicted
in last year		 Change Comment
Clutch size 34 1968-2002 97 None        
Brood size 34 1968-2002 111 None        
Daily failure rate (eggs) 34 1968-2002 124 Curvilinear 0.0147 nests/day 0.0102 nests/day -0.0045 nests/day  
Daily failure rate (chicks) 34 1968-2002 89 Linear decline 0.0193 nests/day 0.0086 nests/day -0.0107 nests/day  
Laying date 34 1968-2002 141 Curvilinear day 167 day 162 -5 days  
Percentage juveniles (CES) 18 1984-2002 59 Smoothed trend 87 productivity index 102 productivity index 14%  
Percentage juveniles (CES) 10 1992-2002 70 Smoothed trend 100 productivity index 102 productivity index 0%  
Percentage juveniles (CES) 5 1997-2002 70 Smoothed trend 96 productivity index 102 productivity index 4%  
 
Clutch size graph
Brood size graph
Egg nest failure graph
Chick nest failure graph
Laying date graph
CES productivity graph
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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., Beaven, L.P., 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. (2005)
Breeding Birds in the Wider Countryside: their conservation status 2004.
BTO Research Report No. 385. BTO, Thetford. (http://www.bto.org/birdtrends)

Pages maintained by Susan Waghorn and Iain Downie: Last updated 18 January, 2006