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WREN
Troglodytes troglodytes
Wren © Tommy Holden
 

• Population
  changes

• Productivity
  trends

• Additional
  information
Conservation listings
Europe: no SPEC category (favourable conservation status in Europe, not concentrated in Europe)
UK: green
UK Biodiversity Action Plan: priority species (Fair Isle & St Kilda races only)
Long-term trend
UK, England: moderate increase
UK population size
8,512,000 territories in 2000 (1988–91 Atlas estimate updated using CBC/BBS trend: BiE04, APEP06)
Status summary
The Wren's current UK population estimate is the highest for any species. Abundance can vary sharply from year to year in this species, however, although this is not evident from the smoothed trends presented here. Annual numbers are influenced by mortality rates that may be very high in severe winters and by the species' high breeding potential (Peach et al. 1995b). Wren numbers in the UK were greatly depleted by the cold winter of 1962/63 (Marchant et al. 1990). Following a rapid recovery up to the mid 1970s, abundance fell again in response to a further series of cold winters only to return to its previous high level. BBS results suggest that increase since 1994 has been much stronger in Scotland and Northern Ireland than in Wales and England. Rather fewer nests are now failing at the egg stage. Numbers have risen widely in Europe since 1980 (PECBMS 2007).
 

Population changes
CBC/BBS UK graph
 
Table of population changes for Wren

Source Period
(yrs)		 Years Plots
(n)		 Change
(%)		 Lower
limit		 Upper
limit		 Alert Comment
CBC/BBS UK 39 1967-2006 818 98 74 120    
  25 1981-2006 1155 51 36 60    
  10 1996-2006 2265 28 22 30    
  5 2001-2006 2392 1 -2 3    
CBC/BBS England 39 1967-2006 651 90 65 118    
  25 1981-2006 910 42 28 55    
  10 1996-2006 1764 22 17 24    
  5 2001-2006 1847 -2 -4 0    
CES adults 22 1984-2006 95 58 35 87    
  10 1996-2006 107 -1 -9 7    
  5 2001-2006 98 -11 -18 -4    
CES juveniles 22 1984-2006 94 30 6 61    
  10 1996-2006 106 -5 -15 5    
  5 2001-2006 99 -16 -23 -11    
BBS UK 11 1995-2006 2107 24 18 27    
  10 1996-2006 2164 25 19 28    
  5 2001-2006 2392 3 1 5    
BBS England 11 1995-2006 1634 16 11 18    
  10 1996-2006 1676 20 15 22    
  5 2001-2006 1847 2 -1 3    
BBS Scotland 11 1995-2006 194 66 43 80    
  10 1996-2006 195 56 34 66    
  5 2001-2006 205 11 2 21    
BBS Wales 11 1995-2006 185 17 4 25    
  10 1996-2006 192 21 8 28    
  5 2001-2006 223 0 -5 6    
BBS N.Ireland 11 1995-2006 82 62 21 95    
  10 1996-2006 88 40 13 56    
  5 2001-2006 102 3 -5 12    

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

BBS N Ireland graph
 

Productivity trends
Table of productivity changes for Wren

Variable Period
(yrs)		 Years Mean
annual
sample		 Trend Modelled
in first year		 Modelled
in 2006		 Change Comment
Clutch size 38 1968-2006 95 None        
Brood size 38 1968-2006 96 None        
Daily failure rate (eggs) 38 1968-2006 141 Linear decline 1.83% nests/day 1.43% nests/day -21.9%  
Daily failure rate (chicks) 38 1968-2006 98 None        
Laying date 38 1968-2006 87 Linear decline May 14 May 9 -5 days  
Juvenile to Adult ratio (CES) 22 1984-2006 98 Smoothed trend 114 Index value 100 Index value -12%  
Juvenile to Adult ratio (CES) 10 1996-2006 109 Smoothed trend 105 Index value 100 Index value -5%  
Juvenile to Adult ratio (CES) 5 2001-2006 100 Smoothed trend 106 Index value 100 Index value -6%  

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

Additional information
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This report should be cited as:
Baillie, S.R., Marchant, J.H., Leech, D.I., Joys, A.C., Noble, D.G.,
Barimore, C., Grantham, M.J., Risely, K. & Robinson, R.A. (2009).
Breeding Birds in the Wider Countryside: their conservation status 2008.
BTO Research Report No. 516. BTO, Thetford. (http://www.bto.org/birdtrends)

Pages maintained by Iain Downie, Mandy T Andrews and Laura Smith: Last updated 18.02.2009