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BTO Blueline

SHELDUCK
Tadorna tadorna
Shelduck © Tommy Holden
 

• Population
  changes

• Productivity
  trends

• Additional
  information
Conservation listings
Europe: no SPEC category (favourable conservation status in Europe, not concentrated in Europe)
UK: amber (localised in winter, >20% of NW European population in winter)
Long term-trend
UK: rapid increase
UK population size
10,900 pairs in 1990 (1988–91 Atlas: APEP06); 5,800–10,800 pairs in 2000 (updated using CBC and BBS trends: BiE04)
Status summary
Shelducks occurred on relatively few CBC plots, most of which were close to a coast or an estuary, and it is unclear how well the CBC trend represented that of the UK breeding population. The CBC showed a substantial increase from the mid 1960s until the early 1980s, some decrease during the 1980s, and stability during the 1990s, although the wide confidence intervals provide scope for other interpretations. Population increase was associated with expansion of range, measured as an additional 20% of occupied 10-km squares in Britain between 1968–72 and 1988–91 (Gibbons et al. 1993). The UK winter Shelduck population rose during the 1960s and 1970s, alongside the rise in breeding numbers, but has been falling again since the mid 1990s (Banks et al. 2006). The BBS index is affected by occasional large counts, and as a result is difficult to interpret.
 

Population changes
CBC all habitats graph
 
Table of population changes for Shelduck

Source Period
(yrs)		 Years Plots
(n)		 Change
(%)		 Lower
limit		 Upper
limit		 Alert Comment
CBC all habitats 31 1968-1999 18 300 94 787   Small sample
  25 1974-1999 21 12 -40 118    
  10 1989-1999 21 3 -21 40    
  5 1994-1999 23 4 -18 39    
BBS UK 10 1995-2005 125 -1 -29 39    
  5 2000-2005 132 29 -4 77    
BBS England 10 1995-2005 103 21 -9 55    
  5 2000-2005 106 36 -5 90    

BBS acknowledgement
 
BBS UK graph
BBS England graph
 

Productivity trends
Productivity information is not currently available for this species
 

Additional information
BTO blue divider
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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