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BTO Blueline
REED WARBLER
Acrocephalus scirpaceus
Reed Warbler © Graham Austin
 
Conservation listings

Europe: SPEC category 4, secure
UK: Green

Long-term trend
UK: Shallow decline over past 15 years
Linear waterways: Moderate increase
 
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 partially 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 33 1967-2000 41 95 31 227    
  25 1975-2000 49 120 60 237    
  10 1990-2000 81 52 25 92    
  5 1995-2000 119 29 18 40    
CBC/BBS England 33 1967-2000 39 72 12 252    
  25 1975-2000 46 93 37 179    
  10 1990-2000 78 42 21 69    
  5 1995-2000 115 26 16 37    
WBS waterways 25 1975-2000 20 81 24 220    
  10 1990-2000 27 43 18 66    
  5 1995-2000 30 15 -7 32    
CES adults 17 1984-2001 52 -11 . .    
  10 1991-2001 62 21 . .    
  5 1996-2001 64 4 . .    
CES juveniles 17 1984-2001 54 -1 . .    
  10 1991-2001 65 30 . .    
  5 1996-2001 67 13 . .    
BBS UK 8 1994-2002 87 29 6 57    
BBS England 8 1994-2002 83 20 -2 46    
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 33 1968-2001 99 None        
Brood size 33 1968-2001 112 None        
Daily failure rate (eggs) 33 1968-2001 126 Curvilinear 0.0151 nests/day 0.0112 nests/day -0.0039 nests/day  
Daily failure rate (chicks) 33 1968-2001 90 Linear decline 0.0188 nests/day 0.0095 nests/day -0.0093 nests/day  
Laying date 33 1968-2001 143 None        
Percentage juveniles (CES) 17 1984-2001 59 Smoothed trend 86 productivity index 101 productivity index 17%  
Percentage juveniles (CES) 10 1991-2001 70 Smoothed trend 97 productivity index 101 productivity index 3%  
Percentage juveniles (CES) 5 1996-2001 72 Smoothed trend 94 productivity index 101 productivity index 6%  
 
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:
Crick, H.Q.P., Marchant, J.H., Noble, D.G., Baillie, S.R., 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. (2004)
Breeding Birds in the Wider Countryside: their conservation status 2003.
BTO Research Report No. 353. BTO, Thetford. (http://www.bto.org/birdtrends2003)

Pages maintained by Susan Waghorn and Iain Downie: Last updated 16 February, 2009