BTO - Breeding Birds of the Wider Countryside: Song Thrush

SONG THRUSH
Turdus philomelos

Conservation listings

Europe: no SPEC category (concentrated in Europe, conservation status favourable)
UK: red (>50% population decline)

Long-term trend

UK, England: rapid decline

Distribution maps

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

Status summary

The CBC shows a rapid decline in Song Thrush abundance that began in the mid 1970s. The second half of this decline can also be seen in the CES index. CES productivity showed an initial decrease, followed by stability, and NRS data indicate that breeding performance has improved during this period. Changes in survival of juveniles in their first year of life probably drove the decline (Thomson et al. 1997, Siriwardena et al. 1998a). Recent CBC/BBS data suggest that the decline has at least levelled off, and may now be reversing. Falling Song Thrush abundance has been linked to agricultural intensification (Fuller et al. 1995), but woodland-specific factors such as drainage and the depletion of the shrub layer may also be implicated (Vanhinsbergh et al. 2003). Adverse weather increased mortality rates but was not the primary driver of population decline, which remains unknown (Robinson et al. 2004).

Table of population changes for Song Thrush

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert	Comment
CBC/BBS UK	35	1967-2002	516	-51	-58	-44	>50
	25	1977-2002	646	-33	-43	-25	>25
	10	1992-2002	1290	20	11	26
	5	1997-2002	1692	20	16	24
CBC/BBS England	35	1967-2002	416	-53	-62	-46	>50
	25	1977-2002	515	-38	-47	-29	>25
	10	1992-2002	1013	19	10	26
	5	1997-2002	1310	19	16	23
CES adults	18	1984-2002	79	-26	.	.	*[>25]**
	10	1992-2002	90	-7	.	.
	5	1997-2002	87	5	.	.
CES juveniles	18	1984-2002	64	-51	.	.	*[>50]**
	10	1992-2002	73	-7	.	.
	5	1997-2002	73	3	.	.
BBS UK	9	1994-2003	1428	18	12	24
BBS England	9	1994-2003	1104	15	9	21
BBS Scotland	9	1994-2003	132	27	5	52
BBS Wales	9	1994-2003	130	30	12	51
BBS N.Ireland	9	1994-2003	53	26	-10	78

Table of productivity information for Song Thrush

Variable	Period (yrs)	Years	Mean annual sample	Trend	Predicted in first year	Predicted in last year	Change	Comment
Clutch size	34	1968-2002	168	None
Brood size	34	1968-2002	187	None
Daily failure rate (eggs)	21	1981-2002	324	Linear decline	0.0418 nests/day	0.0278 nests/day	-0.014 nests/day
Daily failure rate (chicks)	21	1981-2002	240	None
Laying date	34	1968-2002	195	None
Percentage juveniles (CES)	18	1984-2002	86	Smoothed trend	161 productivity index	102 productivity index	-38%[>25]
Percentage juveniles (CES)	10	1992-2002	99	Smoothed trend	100 productivity index	102 productivity index	0%
Percentage juveniles (CES)	5	1997-2002	98	Smoothed trend	105 productivity index	102 productivity index	-5%


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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