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SWALLOW Hirundo rustica
 
Conservation Listings Long term trend

Table 4/Amber
(25-49% Population decline)
Biodiversity Steering Group Conservation Concern List

UK: Fluctuations with no long-term trend
 
Status Summary
The Amber listing of the Swallow was based on a statistical artefact that is avoided by the techniques now used with CBC data. Nevertheless, the species is probably not censused ideally by the CBC because of its semi-colonial habits, and some conservationists remain concerned about it. The BBS, however, suggests that Swallow populations are currently increasing. 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. Detailed analysis has shown that population fluctuations are most strongly related to losses on their wintering grounds (Baillie & Peach 1992). The trend towards earlier laying can be partially 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 all habitats 30 1968-1998 79 21 -9 52    
  25 1973-1998 80 39 4 73    
  10 1988-1998 78 26 8 45    
  5 1993-1998 78 20 5 35    
CBC farmland 30 1968-1998 63 35 . .    
  25 1973-1998 63 53 . .    
  10 1988-1998 65 27 . .    
  5 1993-1998 64 20 . .    
BBS UK 5 1994-1999 1353 10 5 16    
BBS England 5 1994-1999 1051 6 0 13    
BBS Scotland 5 1994-1999 128 1 -15 19    
BBS Wales 5 1994-1999 115 37 14 66    
BBS N.Ireland 5 1994-1999 49 14 -17 56   Small sample
The Breeding Bird Survey is jointly funded by BTO, JNCC and RSPB
 
 
Table of productivity information
Variable Period
(yrs)
Years Mean
annual
sample
Trend Predicted
in first year
Predicted
in last year
Change Comment
Clutch size 30 1968-1998 186 None        
Brood size 30 1968-1998 303 Linear increase 4.13 chicks 4.25 chicks 0.12 chicks  
Daily failure rate (eggs) 30 1968-1998 232 Curvilinear 0.0028 nests/day 0.0026 nests/day -0.0002 nests/day  
Daily failure rate (chicks) 30 1968-1998 205 Linear increase 0.0025 nests/day 0.0052 nests/day 0.0027 nests/day  
Laying date 30 1968-1998 93 Curvilinear day 170 day 164 -6 days  
 
Insufficient data on CES
available for this species
   


The report should be cited as: Baillie, S.R., Crick, H.Q.P., Balmer, D.E., Bashford, R.I., Beaven, L.P., Freeman, S.N., Marchant, J.H., Noble, D.G., Raven, M.J., Siriwardena, G.M., Thewlis, R. and Wernham, C.V. (2001) Breeding Birds in the Wider Countryside: their conservation status 2000. BTO Research Report No. 252. BTO, Thetford. (http://www.bto.org/birdtrends)




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Last updated: 28 March, 2001

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