Contents of report
Breeding Bird Survey
Common Birds Census
Constant Effort Sites
Nest Record Scheme
Waterways Bird Survey
Alerts
Summary
What the categories mean
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REED WARBLER Acrocephalus scirpaceus
 
Conservation Listings Long term trend

Unlisted/Green
Biodiversity Steering Group
Conservation Concern List

UK: Shallow decline over past 14 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 is likely to provide better coverage of the population and 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 19% to 13%) and a small improvement is apparent in CES productivity. The trend in laying date 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 30 1968-1998 24 103 43 253   Unrepresentative?
  25 1973-1998 25 122 67 251   Unrepresentative?
  10 1988-1998 26 40 18 78   Unrepresentative?
  5 1993-1998 29 39 28 54   Unrepresentative?
WBS waterways 23 1975-1998 19 71 19 246   Small sample
  10 1988-1998 25 47 21 68    
  5 1993-1998 29 16 -3 37    
CES adults 14 1984-1998 51 -14 . .    
  10 1988-1998 59 4 . .    
  5 1993-1998 66 14 . .    
CES juveniles 14 1984-1998 52 -10 . .    
  10 1988-1998 61 18 . .    
  5 1993-1998 69 16 . .    
BBS UK 5 1994-1999 82 15 -7 42    
BBS England 5 1994-1999 79 14 -8 41    
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 30 1968-1998 102 None        
Brood size 30 1968-1998 114 None        
Daily failure rate (eggs) 30 1968-1998 128 None        
Daily failure rate (chicks) 30 1968-1998 91 Linear decline 0.0177 nests/day 0.0117 nests/day -0.006 nests/day  
Laying date 30 1968-1998 147 Curvilinear day 166 day 164 -2 days  
Percentage juveniles (CES) 14 1984-1998 57 Smoothed trend 90 productivity index 100 productivity index 12%  
Percentage juveniles (CES) 10 1988-1998 67 Smoothed trend 91 productivity index 100 productivity index 9%  
Percentage juveniles (CES) 5 1993-1998 75 Smoothed trend 99 productivity index 100 productivity index 1%  
 

 

   



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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