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BTO Blueline
TAWNY OWL
Strix aluco
 Tawny Owl © 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: stable
UK population size
19,400 pairs in 2000 (1988–91 Atlas estimate updated using CBC/BBS trend: BiE04, APEP06)
Status summary
As a nocturnal species, Tawny Owl is poorly covered by the BTO's monitoring schemes. The pattern shown by CBC/BBS is a relatively stable one, however, in keeping with the longevity, sedentary behaviour, and slow breeding rate of this species. There is a slight indication from CBC/BBS of a shallow downward trend since the early 1970s, although the data for England alone appear more stable. It may be relevant to this possible long-term change that Gibbons et al. (1993) found evidence for a contraction of the species' UK range between the two atlas periods. The substantial improvements in nest success during the c.29-day egg stage could be linked to the declining impact of organochlorine pesticides, which were banned in the 1960s. Special surveys of this species took place in 2005 (click here).
 

Population changes
CBC/BBS Graph
 
Table of population changes for Tawny Owl

Source Period
(yrs)		 Years Plots
(n)		 Change
(%)		 Lower
limit		 Upper
limit		 Alert Comment
CBC/BBS UK 38 1967-2005 75 -9 -41 31    
  25 1980-2005 87 -27 -42 -6 >25  
  10 1995-2005 113 -19 -31 2    
  5 2000-2005 90 -17 -30 3    
CBC/BBS England 38 1967-2005 63 -2 -39 64    
  25 1980-2005 73 -17 -38 12    
  10 1995-2005 97 -8 -27 14    
  5 2000-2005 78 -13 -25 7    
BBS UK 10 1995-2005 82 -18 -32 1   Nocturnal species
  5 2000-2005 82 -19 -34 2   Nocturnal species
BBS England 10 1995-2005 70 -7 -23 25   Nocturnal species
  5 2000-2005 72 -14 -26 5   Nocturnal species

BBS acknowledgement
 
CBC/BBS England graph
BBS UK graph
BBS England graph
 

Productivity trends
Table of productivity changes for Tawny Owl

Variable Period
(yrs)		 Years Mean
annual
sample		 Trend Modelled
in first year		 Modelled
in 2005		 Change Comment
Clutch size 37 1968-2005 76 None        
Brood size 37 1968-2005 135 None        
Daily failure rate (eggs) 37 1968-2005 53 Linear decline 0.95% nests/day 0.19% nests/day -80%  
Daily failure rate (chicks) 37 1968-2005 80 Curvilinear 0.3% nests/day 0.12% nests/day -60%  
Laying date 37 1968-2005 14 Linear decline Mar 29 Mar 22 -7 days Small sample

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

 

 

Insufficient data on CES
available for this species
 

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