BTO - Breeding Birds of the Wider Countryside: Long-tailed Tit

LONG-TAILED TIT
Aegithalos caudatus

• Population
changes

• Productivity
trends

• Additional
information

Conservation listings

Europe: no SPEC category (favourable conservation status in Europe, not concentrated in Europe)
UK: green

Long-term trend

England: moderate increase

UK population size

273,000 territories in 2000 (1988–91 Atlas estimate updated using CBC/BBS trend: BiE04, APEP06)

Status summary

This species undergoes wide fluctuations in numbers, suffering heavy mortality when winters are severe, but able to recover quickly by virtue of its high breeding potential. Numbers were low after the severe winters of the early 1960s and again during a series of relatively cold winters beginning in the late 1970s. The starting years of the 25-year and longest monitoring periods coincided with troughs in population, thus exaggerating the long-term trend. Both CBC/BBS and CES index trends show progressive increases in Long-tailed Tit abundance beginning in the mid 1980s, but tailing off in recent years. Clutch and brood sizes have become smaller since the 1960s and, curiously, nest losses have switched from the egg to the chick stage. The marked trend towards earlier laying may be explained by recent climatic changes (Crick & Sparks 1999). Numbers have risen widely in Europe since 1980 (PECBM 2006).

Population changes

Table of population changes for Long-tailed Tit

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert
CBC/BBS England	38	1967-2005	283	73	31	138
	25	1980-2005	378	67	38	96
	10	1995-2005	724	-2	-9	5
	5	2000-2005	761	-6	-12	0
CES adults	21	1984-2005	77	24	-4	67
	10	1995-2005	91	-8	-18	6
	5	2000-2005	86	-10	-19	3
CES juveniles	21	1984-2005	69	-11	-33	30
	10	1995-2005	86	-20	-32	-8
	5	2000-2005	81	-29	-38	-14	>25
BBS UK	10	1995-2005	735	0	-8	9
	5	2000-2005	843	-7	-14	0
BBS England	10	1995-2005	645	-4	-11	4
	5	2000-2005	740	-4	-11	2
BBS Wales	10	1995-2005	53	-5	-25	24
	5	2000-2005	61	-7	-22	17

Productivity trends

Table of productivity changes for Long-tailed Tit

Variable	Period (yrs)	Years	Mean annual sample	Trend	Modelled in first year	Modelled in 2005	Change	Comment
Clutch size	37	1968-2005	33	Linear decline	7.65 eggs	6.44 eggs	-15.8%
Brood size	37	1968-2005	27	Curvilinear	6.72 chicks	6.28 chicks	-6.6%	Small sample
Daily failure rate (eggs)	37	1968-2005	52	Linear decline	3.62% nests/day	0.84% nests/day	-76.8%
Daily failure rate (chicks)	37	1968-2005	36	Linear increase	0.83% nests/day	1.59% nests/day	91.6%
Laying date	37	1968-2005	43	Linear decline	Apr 21	Apr 6	-15 days
Juvenile to Adult ratio (CES)	21	1984-2005	83	Smoothed trend	125 Index value	100 Index value	-20%
Juvenile to Adult ratio (CES)	10	1995-2005	98	Smoothed trend	104 Index value	100 Index value	-4%
Juvenile to Adult ratio (CES)	5	2000-2005	94	Smoothed trend	128 Index value	100 Index value	-22%

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