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BTO Blueline
GARDEN WARBLER
Sylvia borin
 Garden Warbler © Tommy Holden
 

• Population
  changes

• Productivity
  trends

• Additional
  information
Conservation listings
Europe: no SPEC category (concentrated in Europe, conservation status favourable)
UK: green
Long-term trend
UK, England: shallow decline
UK population size
190,000 territories in 2000 (1988–91 Atlas estimate updated using CBC/BBS trend: BiE04, APEP06)
Status summary
Garden Warbler abundance has varied alongside that of other trans-Saharan migrant warblers (Siriwardena et al. 1998b), probably reflecting the influence of changes in their winter environment. Despite large short-term fluctuations in abundance, the CBC/BBS and CES now both suggest the population is in long-term decline. There has been a substantial increase in nest losses at the chick stage, and post-fledging productivity, as measured by the CES, has declined sharply since 1983, raising BTO alerts.
 

Population changes
CBC/BBS UK graph
 
Table of population changes for Garden Warbler

Source Period
(yrs)		 Years Plots
(n)		 Change
(%)		 Lower
limit		 Upper
limit		 Alert Comment
CBC/BBS UK 38 1967-2005 187 -21 -42 19    
  25 1980-2005 247 20 -9 59    
  10 1995-2005 453 -16 -25 -8    
  5 2000-2005 416 -12 -21 -6    
CBC/BBS England 38 1967-2005 158 -23 -49 19    
  25 1980-2005 208 9 -14 46    
  10 1995-2005 373 -18 -27 -11    
  5 2000-2005 339 -14 -21 -9    
CES adults 21 1984-2005 64 -17 -39 23    
  10 1995-2005 70 -23 -37 -6    
  5 2000-2005 59 -10 -22 7    
CES juveniles 21 1984-2005 63 -41 -55 -7 >25  
  10 1995-2005 69 -33 -43 -21 >25  
  5 2000-2005 63 -4 -20 23    
BBS UK 10 1995-2005 396 -19 -28 -10    
  5 2000-2005 400 -11 -19 -5    
BBS England 10 1995-2005 323 -20 -27 -10    
  5 2000-2005 325 -13 -22 -7    
BBS Wales 10 1995-2005 54 -29 -46 -8 >25  
  5 2000-2005 55 -17 -31 -2    

BBS acknowledgement
 
CBC/BBS England graph
CES adult abundance graph
CES juvenile abundance graph
BBS UK graph
BBS England graph
BBS Wales graph
 

Productivity trends
Table of productivity changes for Garden Warbler

Variable Period
(yrs)		 Years Mean
annual
sample		 Trend Modelled
in first year		 Modelled
in 2005		 Change Comment
Clutch size 37 1968-2005 16 None       Small sample
Brood size 37 1968-2005 24 None       Small sample
Daily failure rate (eggs) 37 1968-2005 22 None       Small sample
Daily failure rate (chicks) 37 1968-2005 19 None       Small sample
Laying date 37 1968-2005 21 Linear decline May 28 May 21 -7 days Small sample
Juvenile to Adult ratio (CES) 21 1984-2005 77 Smoothed trend 140 Index value 100 Index value -29%  
Juvenile to Adult ratio (CES) 10 1995-2005 84 Smoothed trend 92 Index value 100 Index value 9%  
Juvenile to Adult ratio (CES) 5 2000-2005 75 Smoothed trend 78 Index value 100 Index value 29%  

 
Clutch size graph
Brood size graph
Egg nest failure graph
Chick nest failure graph
Laying date graph
CES productivity graph
 

Additional information
BTO blue divider
BirdWeb logo, click to go to BirdWeb

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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., Barimore, C., Coombes, R.H.,
Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. & Thewlis, R.M. (2007)
Breeding Birds in the Wider Countryside: their conservation status 2007.
BTO Research Report No. 487. BTO, Thetford. (http://www.bto.org/birdtrends)

Pages maintained by Susan Waghorn and Iain Downie: Last updated 3 January, 2008