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JAY Garrulus glandarius
 
Conservation Listings Long term trend

Unlisted/Green
Biodiversity Steering Group: Unlisted

UK: Fluctuating with no long-term trend; shallow decline over last 10 years
 
Status Summary
The UK Jay population remained stable in the species' preferred woodland habitat until the late 1980s, after which a decline may have begun, following an earlier decline on farmland CBC plots (Gregory & Marchant 1996). The BBS also suggests that a shallow decline may be in progress. However, low statistical confidence means that these trends should currently only be monitored rather than trigger a conservation alert. Although sample sizes are small, nest failure rates at the egg stage (21 days, comprising 16 days incubation + 5 days laying) have fallen from 69% to 39% and it would be interesting to investigate the causes of this drop.
 
 
Table of population changes for Jay
Source Period
(yrs)
Years Plots
(n)
Change
(%)
Lower
limit
Upper
limit
Alert Comment
CBC all habitats 30 1968-1998 112 -10 -27 7    
  25 1973-1998 118 -13 -27 0    
  10 1988-1998 115 -13 -22 -5    
  5 1993-1998 118 -3 -10 3    
CBC farmland 30 1968-1998 30 -3 . .    
  25 1973-1998 31 -16 . .    
  10 1988-1998 32 -1 . .    
  5 1993-1998 32 10 . .    
CBC woodland 30 1968-1998 64 -15 . .    
  25 1973-1998 69 -16 . .    
  10 1988-1998 72 -19 . .    
  5 1993-1998 75 -4 . .    
BBS UK 5 1994-1999 480 -15 -24 -5    
BBS England 5 1994-1999 421 -19 -28 -9    
BBS Wales 5 1994-1999 46 -3 -33 41   Small sample
The Breeding Bird Survey is jointly funded by BTO, JNCC and RSPB
 
 
Table of productivity information for Jay
Variable Period
(yrs)
Years Mean
annual
sample
Trend Predicted
in first year
Predicted
in last year
Change Comment
Brood size 30 1968-1998 12 None       Small sample
Daily failure rate (eggs) 30 1968-1998 11 Linear decline 0.0542 nests/day 0.0234 nests/day -0.0308 nests/day Small sample
 
Insufficient data on clutch size
available for this species
Insufficient data on nestling failure available for this species

 

Insufficient data on laying date
available for this species

 

 

Insufficient data on CES
available for this species

 

 

   



The report should be cited as: Baillie, S.R., Crick, H.Q.P., Balmer, D.E., Bashford, R.I., Beaven, L.P., Freeman, S.N., Marchant, J.H., Noble, D.G., Raven, M.J., Siriwardena, G.M., Thewlis, R. and Wernham, C.V. (2001) Breeding Birds in the Wider Countryside: their conservation status 2000. BTO Research Report No. 252. BTO, Thetford. (http://www.bto.org/birdtrends)

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Last updated: Last updated: 9 April, 2001

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