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BTO Blueline
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BTO Blueline

Corvus frugilegus

Rook © G H Higginbotham
Conservation listings

Europe: no SPEC category, secure
UK: Green

Long-term trend
UK: moderate increase
Status summary
Relatively few rookeries fell within CBC plots, but an index calculated from the available nest counts shows a shallow, long-term increase (Wilson et al. 1998). The trend is confirmed by the results of the latest BTO rookeries survey, which identified a 40% increase in abundance between 1975 and 1996 (Marchant & Gregory 1999). This increase has been associated with an increase in brood size and probably reflects the species' adaptability in the face of agricultural change. BBS sightings suggest decrease in England but increase in Northern Ireland since 1994; BBS nest counts have not yet been investigated.
BBS UK graph
Table of population changes for Rook
Source Period
Years Plots
Alert Comment
BBS UK 8 1994-2002 1002 0 -8 8    
BBS England 8 1994-2002 791 -9 -17 0    
BBS Scotland 8 1994-2002 97 5 -21 40    
BBS Wales 8 1994-2002 66 -4 -33 39    
BBS N.Ireland 8 1994-2002 46 58 7 132    
BBS acknowledgement
BBS England graph
BBS Scotland graph
BBS Wales graph
BBS N Ireland graph
Table of productivity information for Rook
Variable Period
Years Mean
Trend Predicted
in first year
in last year
Change Comment
Clutch size 33 1968-2001 14 Curvilinear 4.15 eggs 3.88 eggs -0.27 eggs Small sample
Brood size 33 1968-2001 94 Linear increase 2.32 chicks 2.8 chicks 0.48 chicks  
Daily failure rate (eggs) 33 1968-2001 39 None        
Daily failure rate (chicks) 33 1968-2001 61 None        
Laying date 33 1968-2001 13 None       Small sample
Chick size graph
Brood size graph
Egg nest failure graph
Chick nest failure graph
Laying date graph
Insufficient data on CES
available for this species
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This report should be cited as:
Crick, H.Q.P., Marchant, J.H., Noble, D.G., Baillie, S.R., Balmer, D.E., Beaven, L.P., Coombes, R.H.,
Downie, I.S., Freeman, S.N., Joys, A.C., Leech, D.I., Raven, M.J., Robinson, R.A. and Thewlis, R.M. (2004)
Breeding Birds in the Wider Countryside: their conservation status 2003.
BTO Research Report No. 353. BTO, Thetford. (http://www.bto.org/birdtrends2003)

Pages maintained by Susan Waghorn and Iain Downie: Last updated 16 February, 2009