BTO - Breeding Birds of the Wider Countryside: Whitethroat

WHITETHROAT
Sylvia communis

• Population
changes

• Productivity
trends

• Additional
information

Conservation listings

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

Long-term trend

UK, England: rapid decline, followed by shallow increase

UK population size

945,000 territories in 2000 (1988–91 Atlas estimate updated using CBC/BBS trend: BiE04, APEP06)

Status summary

Whitethroat populations had been stable for a few years up to 1968 but, after a normal autumn departure for West Africa, crashed by around 70% between the 1968 and 1969 breeding seasons. They fluctuated around their lower level until the mid 1980s, since when they have sustained a consistent shallow recovery. Recovery has been most apparent along linear waterways. In a pioneering study, Winstanley et al. (1974) linked the 1969 crash to droughts in the Whitethroat's wintering grounds in the western Sahel, just south of the Sahara Desert. Annual fluctuations in abundance, which are not shown in the smoothed trends, correlate to those in overwinter survival (Baillie & Peach 1992). Other trans-Saharan migrant warblers have shared similarly timed population changes in abundance (Siriwardena et al. 1998b). Productivity, as measured by CES, rose during the 1980s and has since fluctuated. It seems likely that habitat loss since the 1960s, particularly on farmland, will eventually limit the degree of recovery. Numbers have risen widely in Europe since 1980 (PECBM 2006).

Population changes

Table of population changes for Whitethroat

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert
CBC/BBS UK	38	1967-2005	415	-62	-73	-49	>50
	25	1980-2005	566	58	24	100
	10	1995-2005	1178	22	15	28
	5	2000-2005	1225	9	4	14
CBC/BBS England	38	1967-2005	361	-63	-74	-48	>50
	25	1980-2005	490	61	29	110
	10	1995-2005	1018	20	13	24
	5	2000-2005	1051	8	4	11
WBS waterways	30	1975-2005	41	154	9	369
	25	1980-2005	44	321	159	571
	10	1995-2005	55	67	32	108
	5	2000-2005	46	33	15	51
CES adults	21	1984-2005	59	-28	-48	-9	>25
	10	1995-2005	70	-25	-37	-12
	5	2000-2005	63	39	21	63
CES juveniles	21	1984-2005	64	-39	-55	-20	>25
	10	1995-2005	75	-31	-48	-18	>25
	5	2000-2005	68	46	14	70
BBS UK	10	1995-2005	1108	19	11	26
	5	2000-2005	1207	9	5	14
BBS England	10	1995-2005	956	18	11	24
	5	2000-2005	1035	8	4	11
BBS Scotland	10	1995-2005	63	89	42	165
	5	2000-2005	69	34	14	63
BBS Wales	10	1995-2005	72	-28	-44	-14	>25
	5	2000-2005	82	-18	-31	-6

Productivity trends

Table of productivity changes for Whitethroat

Variable	Period (yrs)	Years	Mean annual sample	Trend	Modelled in first year	Modelled in 2005	Change	Comment
Clutch size	37	1968-2005	29	None				Small sample
Brood size	37	1968-2005	63	Curvilinear	4.25 chicks	4.1 chicks	-3.6%
Daily failure rate (eggs)	37	1968-2005	41	None
Daily failure rate (chicks)	37	1968-2005	48	None
Laying date	37	1968-2005	18	Curvilinear	May 26	May 19	-7 days	Small sample
Juvenile to Adult ratio (CES)	21	1984-2005	74	Smoothed trend	101 Index value	100 Index value	-1%
Juvenile to Adult ratio (CES)	10	1995-2005	86	Smoothed trend	133 Index value	100 Index value	-25%
Juvenile to Adult ratio (CES)	5	2000-2005	77	Smoothed trend	138 Index value	100 Index value	-27% >25

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