BTO - Breeding Birds of the Wider Countryside: Swallow

SWALLOW
Hirundo rustica

Conservation listings

Europe: SPEC category 3 (depleted)
UK: amber (European status)

Long-term trend

England: fluctuating, with no long-term trend

Distribution maps

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

Status summary

Swallow was originally amber-listed partly on the strength of a perceived CBC decline, but continues to qualify through its unfavourable European status. Modern methods of estimating population change from CBC give no evidence for long-term decline in the UK (Robinson et al. 2003). Detailed analysis has shown that the population fluctuations are most strongly related to losses on their wintering grounds (Baillie & Peach 1992). More recently, population change has been shown to be correlated with rainfall in the western Sahel on spring passage, but with neither cattle numbers nor nest-site availability in the UK (Robinson et al. 2003). It is likely that, in eastern parts of the UK, the loss of livestock farming and grazed grassland, together with arable intensification, has caused the Swallow population to decline, while an increase in the area of pasture in the west and north has promoted a population increase which has more than compensated for declines elsewhere (Evans & Robinson 2004). Recent BBS data suggest an upturn, at least in Wales. Aspects of breeding performance have shown small contrasting changes, with slight increases in the daily nest failure rate at the egg stage in the 1980s and at the nestling stage in the 1990s. The trend towards earlier laying can be partly explained by recent climate change (Crick & Sparks 1999).

Table of population changes for Swallow

Source	Period (yrs)	Years	Plots (n)	Change (%)	Lower limit	Upper limit	Alert	Comment
CBC/BBS England	35	1967-2002	312	4	-27	40
	25	1977-2002	414	-2	-20	14
	10	1992-2002	936	16	2	32
	5	1997-2002	1254	4	-1	9
BBS UK	9	1994-2003	1437	8	2	14
BBS England	9	1994-2003	1102	4	-2	10
BBS Scotland	9	1994-2003	131	-3	-18	15
BBS Wales	9	1994-2003	133	41	18	69
BBS N.Ireland	9	1994-2003	60	8	-21	47

Table of productivity information for Swallow

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

Clutch size 34 1968-2002 174 None

Brood size 34 1968-2002 282 Curvilinear 4.07 chicks 4.16 chicks 0.09 chicks

Daily failure rate (eggs) 34 1968-2002 217 Curvilinear 0.0028 nests/day 0.0021 nests/day -0.0007 nests/day

Daily failure rate (chicks) 34 1968-2002 191 Linear increase 0.0028 nests/day 0.0049 nests/day 0.0021 nests/day

Laying date 34 1968-2002 87 Curvilinear day 170 day 162 -8 days

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