The British Trust for Ornithology
REED WARBLER
Acrocephalus scirpaceus
Reed Warbler © Graham Austin
 
Conservation listings

Unlisted/Green
Biodiversity Steering Group Conservation Concern List

Long-term trend
UK: Shallow decline over past 15 years
Linear waterways: Moderate increase
 
Status summary
The CBC and WBS show steady increases over time but are unlikely to be representative of the UK Reed Warbler population as a whole. (The CBC index is based on a relatively small sample of mainly coastal plots.) The CES, which may provide better coverage of the population, shows a decline from 1983 until the early 1990s, followed by stability or a partial recovery. NRS breeding performance has improved slightly over time (nest failures at the chick stage (12 days) fell from 20% to 12%) and a small improvement is apparent in CES productivity. The trend towards advancement of laying dates can be partially explained by recent climate change (Crick & Sparks 1999).
 
 
Table of population changes for Reed Warbler
Source Period
(yrs)
Years Plots
(n)
Change
(%)
Lower
limit
Upper
limit
Alert Comment
CBC all habitats 31 1968-1999 24 113 45 277   Unrepresentative?
  25 1974-1999 25 128 66 264   Unrepresentative?
  10 1989-1999 27 48 24 95   Unrepresentative?
  5 1994-1999 29 39 27 55   Unrepresentative?
WBS waterways 24 1975-1999 19 77 16 181   Small sample
  10 1989-1999 26 47 18 65    
  5 1994-1999 30 16 -8 36    
CES adults 15 1984-1999 52 -10 . .    
  10 1989-1999 62 14 . .    
  5 1994-1999 67 14 . .    
CES juveniles 15 1984-1999 54 -2 . .    
  10 1989-1999 64 29 . .    
  5 1994-1999 71 24 . .    
BBS UK 6 1994-2000 85 14 -7 40    
BBS England 6 1994-2000 83 13 -8 39    
The Breeding Bird Survey is jointly funded by BTO, JNCC and RSPB
 
 
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 31 1968-1999 102 None        
Brood size 31 1968-1999 113 None        
Daily failure rate (eggs) 31 1968-1999 127 Curvilinear 0.015 nests/day 0.0115 nests/day -0.0035 nests/day  
Daily failure rate (chicks) 31 1968-1999 90 Linear decline 0.0182 nests/day 0.0107 nests/day -0.0075 nests/day  
Laying date 31 1968-1999 145 Curvilinear day 166 day 163 -3 days  
Percentage juveniles (CES) 15 1984-1999 59 Smoothed trend 87 productivity index 100 productivity index 15%  
Percentage juveniles (CES) 10 1989-1999 70 Smoothed trend 92 productivity index 100 productivity index 8%  
Percentage juveniles (CES) 5 1994-1999 77 Smoothed trend 95 productivity index 100 productivity index 5%  
 




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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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This page last updated: 21 April, 2008

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