BTO - Breeding Birds of the Wider Countryside: Mute Swan

MUTE SWAN
Cygnus olor

Conservation listings

Europe: no SPEC category (concentrated in Europe, conservation status favourable)
UK: amber (>20% of European breeding population)

Long-term trend

UK, England: rapid increase

Distribution maps

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

Status summary

Mute Swan populations have increased progressively on both WBS and CBC/BBS plots since the mid 1980s, perhaps reflecting warmer winter weather and the replacement of anglers' lead weights with non-toxic alternatives (Gibbons et al. 1993). CBC/BBS data indicate that a rapid increase has occurred, but may be less representative of the whole population than WBS figures.The reductions in breeding performance, although statistically significant, may be to some extent artefacts of the relatively small and perhaps unrepresentative annual samples in the 1990s. The recent change of conservation listing from green to amber is unconnected with its UK trend.

Table of population changes for Mute Swan

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert	Comment
CBC/BBS UK	35	1967-2002	59	247	49	646
	25	1977-2002	76	179	60	294
	10	1992-2002	160	57	25	108
	5	1997-2002	216	18	3	36
CBC/BBS England	35	1967-2002	50	201	32	571
	25	1977-2002	65	151	49	275
	10	1992-2002	136	38	14	69
	5	1997-2002	183	8	-7	19
WBS waterways	27	1975-2002	44	70	14	158
	25	1977-2002	44	59	10	121
	10	1992-2002	57	33	10	61
	5	1997-2002	58	6	-5	18
BBS UK	9	1994-2003	174	14	-2	33
BBS England	9	1994-2003	149	-6	-19	9

Table of productivity information for Mute Swan

Variable Period
(yrs) Years Mean
annual
sample Trend Predicted
in first year Predicted
in last year Change Comment

Clutch size 34 1968-2002 18 Linear decline 5.86 eggs 5.08 eggs -0.78 eggs Small sample

Brood size 34 1968-2002 31 None

Daily failure rate (eggs) 34 1968-2002 25 Curvilinear 0.0077 nests/day 0.0443 nests/day 0.0366 nests/day Small sample

Daily failure rate (chicks) 34 1968-2002 19 Linear increase 0.0005 nests/day 0.0029 nests/day 0.0024 nests/day Small sample

Laying date 34 1968-2002 11 None Small sample

Insufficient data on CES
available for this species


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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