BTO - Breeding Birds of the Wider Countryside: Blackbird

BLACKBIRD
Turdus merula

Conservation listings

Europe: no SPEC category (concentrated in Europe, conservation status favourable)
UK: green

Long-term trend

UK, England: shallow decline

Distribution maps

Maps and statistics from British and Irish
atlases can be viewed here.

Status summary

Both CBC/BBS and CES data show long-term declines in Blackbird abundance, but recent increases suggest that the population is starting to recover. The moderate-decline criteria for amber listing and for BTO alerts are no longer met, and the species is now listed as green. CBC results indicate that the decline began in the mid 1970s. Productivity shows no clear temporal trend, and it is likely that changes in survival drove the decline (Siriwardena et al. 1998a). Agricultural intensification is likely to have contributed (Fuller et al. 1995), but, since numbers fell in woodland as well as farmland, additional factors probably operated.

Table of population changes for Blackbird

Source Period
(yrs) Years Plots
(n) Change
(%) Lower
limit Upper
limit Alert Comment

CBC/BBS UK 35 1967-2002 631 -18 -26 -10

25 1977-2002 803 -10 -17 -3

10 1992-2002 1646 14 11 17

5 1997-2002 2171 15 13 17

CBC/BBS England 35 1967-2002 518 -19 -27 -12

25 1977-2002 655 -12 -19 -4

10 1992-2002 1330 13 9 17

5 1997-2002 1732 14 12 16

CES adults 18 1984-2002 94 -6 . .

10 1992-2002 109 6 . .

5 1997-2002 109 11 . .

CES juveniles 18 1984-2002 84 -33 . . [>25]

10 1992-2002 98 -11 . .

5 1997-2002 97 -10 . .

BBS UK 9 1994-2003 1832 18 15 21

BBS England 9 1994-2003 1461 17 14 20

BBS Scotland 9 1994-2003 147 14 1 28

BBS Wales 9 1994-2003 154 22 11 34

BBS N.Ireland 9 1994-2003 62 67 31 113

Table of productivity information for Blackbird

Variable	Period (yrs)	Years	Mean annual sample	Trend	Predicted in first year	Predicted in last year	Change	Comment
Clutch size	34	1968-2002	93	None
Brood size	34	1968-2002	117	Curvilinear	3.32 chicks	3.36 chicks	0.04 chicks
Daily failure rate (eggs)	34	1968-2002	133	None
Daily failure rate (chicks)	34	1968-2002	113	Linear decline	0.0294 nests/day	0.0212 nests/day	-0.0082 nests/day
Laying date	34	1968-2002	113	Curvilinear	day 115	day 114	-1 days
Percentage juveniles (CES)	18	1984-2002	96	Smoothed trend	136 productivity index	102 productivity index	-26%[>25]
Percentage juveniles (CES)	10	1992-2002	111	Smoothed trend	120 productivity index	102 productivity index	-16%
Percentage juveniles (CES)	5	1997-2002	112	Smoothed trend	124 productivity index	102 productivity index	-20%


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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., 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. (2005) Breeding Birds in the Wider Countryside: their conservation status 2004. BTO Research Report No. 385. BTO, Thetford. (http://www.bto.org/birdtrends) Pages maintained by Susan Waghorn and Iain Downie: Last updated 18 January, 2006