Wider Countryside Report Header
BTO Blueline
Main WCR menu image Site navigation menu item Results overview menu item Other info menu item BTO website menu item
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 covered relatively poorly 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 has been a shallow downward trend in the index since the early 1970s. It may be relevant to this possible long-term decline 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 early 1960s. Special post-breeding surveys of this species were conducted in autumn 2005 (click here), following methodology established by an earlier survey in 1989 (Percival 1990).
 

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 39 1967-2006 75 -2 -40 42    
  25 1981-2006 87 -25 -43 -2    
  10 1996-2006 110 -15 -29 5    
  5 2001-2006 82 -6 -21 16    
CBC/BBS England 39 1967-2006 64 -1 -41 48    
  25 1981-2006 74 -19 -39 12    
  10 1996-2006 95 -9 -24 14    
  5 2001-2006 73 -10 -23 10    
BBS UK 11 1995-2006 82 -12 -27 11   Nocturnal species
  10 1996-2006 84 -12 -25 10   Nocturnal species
  5 2001-2006 82 -7 -22 11   Nocturnal species
BBS England 11 1995-2006 70 -5 -24 24   Nocturnal species
  10 1996-2006 72 -6 -24 19   Nocturnal species
  5 2001-2006 73 -10 -25 8   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 2006		 Change Comment
Clutch size 38 1968-2006 78 None        
Brood size 38 1968-2006 139 None        
Daily failure rate (eggs) 38 1968-2006 55 Linear decline 0.95% nests/day 0.18% nests/day -81.1%  
Daily failure rate (chicks) 38 1968-2006 82 Curvilinear 0.31% nests/day 0.11% nests/day -64.5%  
Laying date 38 1968-2006 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
 

BTO Home | JNCC Home
 © British Trust for Ornithology. Charity No 216652 (England and Wales).Charity No SC039193 (Scotland)
Company Limited by Guarantee No 357284 (England and Wales).
Registered Office: The Nunnery, Thetford, Norfolk IP24 2PU, UK.
Terms and Conditions | Privacy Statement          Email:


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