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SEDGE WARBLER Acrocephalus schoenobaenus
 
Conservation Listings Long term trend

Unlisted/Green
Biodiversity Steering Group
Conservation Concern List

UK: Fluctuating with no long-term trend
Farmland: Moderate decline
 
Status Summary
Prior to the inception of the CES and BBS, Sedge Warbler populations were not represented well by any UK monitoring scheme, but the CBC identified a decline, especially on farmland, that ceased in the mid-1970s. The populations monitored by the CBC and WBS have since remained more-or-less stable, a pattern also seen in the BBS results for the last six years. CES provides the best monitoring for Sedge Warbler and it shows large inter-annual fluctuations and a suggestion of a decline through the 1990s. Detailed analysis of BTO datasets has shown that much of the variation in population size is related to changes in adult survival rates which, in turn, are related to changes in rainfall on their Sahel (sub-Saharan) wintering grounds (Peach et al. 1991). No strong trends are apparent in breeding performance, but CES productivity has shown a steady decline since 1983.
 
 
Table of population changes for Sedge Warbler
Source Period
(yrs)
Years Plots
(n)
Change
(%)
Lower
limit
Upper
limit
Alert Comment
CBC all habitats 30 1968-1998 44 -20 -47 7   Unrepresentative
  25 1973-1998 43 13 -9 39   Unrepresentative
  10 1988-1998 39 8 -9 36   Unrepresentative
  5 1993-1998 42 11 0 24   Unrepresentative
CBC farmland 30 1968-1998 24 -48 -70 -5 >25 Unrepresentative
  25 1973-1998 22 -7 -39 58   Unrepresentative
  10 1988-1998 23 4 -18 38   Unrepresentative
  5 1993-1998 25 10 -11 32   Unrepresentative
WBS waterways 23 1975-1998 43 -18 -44 25    
  10 1988-1998 53 -20 -29 -5    
  5 1993-1998 58 2 -6 12    
CES adults 14 1984-1998 61 1 . .    
  10 1988-1998 72 -20 . .    
  5 1993-1998 81 -8 . .    
CES juveniles 14 1984-1998 57 -30 . . [>25*]  
  10 1988-1998 68 -44 . . [>25*]  
  5 1993-1998 77 -26 . . [>25*]  
BBS UK 5 1994-1999 233 14 0 31    
BBS England 5 1994-1999 147 0 -16 18    
BBS Scotland 5 1994-1999 49 39 3 86   Small sample
BBS N.Ireland 5 1994-1999 20 -7 -42 50   Small sample
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 42 None        
Brood size 30 1968-1998 65 None        
Daily failure rate (eggs) 30 1968-1998 49 Curvilinear 0.0147 nests/day 0.0117 nests/day -0.003 nests/day  
Daily failure rate (chicks) 30 1968-1998 55 None        
Laying date 30 1968-1998 56 None        
Percentage juveniles (CES) 14 1984-1998 66 Smoothed trend 164 productivity index 100 productivity index -39%[>25]  
Percentage juveniles (CES) 10 1988-1998 77 Smoothed trend 151 productivity index 100 productivity index -34%[>25*]  
Percentage juveniles (CES) 5 1993-1998 87 Smoothed trend 136 productivity index 100 productivity index -27%[>25*]  
 

 

   



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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