BTO - Breeding Birds of the Wider Countryside: Song Thrush

SONG THRUSH
Turdus philomelos

• Population
changes

• Productivity
trends

• Additional
information

Conservation listings

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

Long-term trend

UK, England: rapid decline

UK population size

1,144,000 territories in 2000 (1988–91 Atlas estimate updated using CBC/BBS trend: BiE04, APEP06)

Status summary

CBC/BBS 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 some partial recovery, and NRS data indicate that nest success has improved since 1981. Changes in survival in the first winter, and perhaps also the post-fledging period, are sufficient to have caused the population decline (Thomson et al. 1997, Siriwardena et al. 1998a, Robinson et al. 2004). The environmental causes of these changes are not known, but changes in farming practices, land drainage, pesticides and predators are all candidates (Fuller et al. 1995, Robinson et al. 2004). In woodland, drainage of damp ground and the depletion of woodland shrub layers through canopy closure and deer browsing may also be implicated (Fuller et al. 2005). Recent CBC/BBS data show consistent increase, but population levels remain relatively low. Recovery of rural Song Thrush populations requires challenging new policy initiatives that should aim to restore nesting cover in scrub and woodland understorey, grazed grassland in arable-dominated areas, and damper soils in summer (Peach et al. 2004).

Population changes

Table of population changes for Song Thrush

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert
CBC/BBS UK	38	1967-2005	631	-50	-57	-43	>50
	25	1980-2005	850	-18	-28	-5
	10	1995-2005	1717	23	17	28
	5	2000-2005	1837	7	4	11
CBC/BBS England	38	1967-2005	502	-52	-60	-42	>50
	25	1980-2005	669	-21	-31	-7
	10	1995-2005	1335	21	16	25
	5	2000-2005	1410	10	7	13
CES adults	21	1984-2005	81	-27	-41	-9	>25
	10	1995-2005	90	-9	-21	5
	5	2000-2005	86	9	-3	26
CES juveniles	21	1984-2005	66	-47	-65	-29	>25
	10	1995-2005	75	9	-9	30
	5	2000-2005	75	7	-10	29
BBS UK	10	1995-2005	1610	22	17	29
	5	2000-2005	1808	8	5	11
BBS England	10	1995-2005	1243	19	13	25
	5	2000-2005	1386	11	7	14
BBS Scotland	10	1995-2005	143	25	9	43
	5	2000-2005	150	5	-6	14
BBS Wales	10	1995-2005	150	35	22	50
	5	2000-2005	181	6	-3	14
BBS N.Ireland	10	1995-2005	65	49	17	88
	5	2000-2005	81	4	-11	21

Productivity trends

Table of productivity changes for Song Thrush

Variable	Period (yrs)	Years	Mean annual sample	Trend	Modelled in first year	Modelled in 2005	Change
Clutch size	37	1968-2005	165	None
Brood size	37	1968-2005	182	None
Daily failure rate (eggs)	24	1981-2005	321	Curvilinear	4.41% nests/day	4.79% nests/day	8.6%
Daily failure rate (chicks)	24	1981-2005	241	None
Laying date	37	1968-2005	191	None
Juvenile to Adult ratio (CES)	21	1984-2005	89	Smoothed trend	142 Index value	100 Index value	-29%
Juvenile to Adult ratio (CES)	10	1995-2005	100	Smoothed trend	80 Index value	100 Index value	25%
Juvenile to Adult ratio (CES)	5	2000-2005	97	Smoothed trend	103 Index value	100 Index value	-3%

Additional information


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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