The Bullfinch has declined in Britain and elsewhere in Europe, but definitive evidence about the cause and demographic mechanism has yet to be published. We review current knowledge, concentrating on analyses of demography, and present new integrated population modelling analyses designed to reveal the demographic changes most important in the decline. It is likely that changes in brood size and clutch size have not been important and our models suggest that the decline can be explained without invoking variation in numbers of breeding attempts or post-fledging survival rates. However, although changes in the egg period daily nest failure rate provide the best explanation for population change during the years of steepest decline, nestling period failures, adult survival and first-year survival could all have been equally important. Egg period nest failure rates have been higher in the preferred habitat, woodland, than in farmland and have fallen over time in farmland, where a larger decline has occurred (65 % versus 28% ), arguing against a causal link with abundance. Despite evidence for a negative effect of agricultural intensification on Bullfinch presence, little evidence exists clearly linking any demographic rate to environmental change and agricultural land-use has had little effect on nest failure rates. Predation appears to have had no significant impact. Future work should focus on contemporary investigations of the importance of hedgerow structure and woodland understorey vegetation.
How to translate text using browser tools
1 December 2001
The Decline of the Bullfinch Pyrrhula pyrrhula in Britain: is the Mechanism Known?
Gavin M. Siriwardena,
Stephen N. Freeman,
Humphrey Q. P. Crick
S. R. Baillie
,
H. Q. P. Crick
,
D. E. Balmer
,
R. I. Bashford
,
L. P. Beaven
,
S. N. Freeman
,
J. H. Marchant
,
D. G. Noble
,
M. J. Raven
,
G. M. Siriwardena
,
R. Thewlis
,
C. V. Wernham
2001. Breeding Birds in the Wider Countryside: their conservation status 2000. BTO Res. Rep. no. 252. Thetford, Norfolk. ( http://www.bto.org/birdtrends). Google Scholar
S. R. Baillie
,
R. D. Gregory
,
G. M. Siriwardena
1997. Farmland bird declines, patterns, processes and prospects. In:
R. C. Kirkwood
(ed.). Biodiversity and Conservation in Agriculture: BCPC Proc. No. 69: 65–87. British Crop Protection Council, Farnham. Google Scholar
D. E. Chamberlain
,
R. J. Fuller
,
M. Shrubb
,
R. G. H. Bunce
,
J. C. Duckworth
,
D. G. Garthwaite
,
A. J. Impey
,
A. D. M. Hart
1999. The effects of agricultural change on birds. BTO Res. Rep. no. 209, Thetford, Norfolk, UK. Google Scholar
H. Q. P. Crick
1992. A bird-habitat coding system for use in Britain and Ireland incorporating aspects of land management and human activity. Bird Study 39: 1–12. Google Scholar
H. Q. P. Crick
,
S. R. Baillie
1996. A review of the BTO's Nest Record Scheme. Its value to the Joint Nature Conservation Committee and Country Agencies, and its methodology. BTO Res. Rep. no. 156. Thetford, Norfolk, UK. Google Scholar
H. Q. P. Crick
,
C. Dudley
,
D. E. Glue
,
D. L. Thomson
1997. UK birds are laying eggs earlier. Nature 388: 526. Google Scholar
H. Q. P. Crick
,
T. H. Sparks
1999. Climate change related to egglaying trends. Nature 399: 423– 424. Google Scholar
D. W. Gibbons
,
W. J. B. Reid
,
R. A. Chapman
1993. The new atlas of breeding birds in Britain and Ireland: 1988–1991. T & AD Poyser, London. Google Scholar
J. J. D. Greenwood,
S. R. Baillie,
H. Q. P. Crick,
J. H. Marchant,
W. J. Peach
1993. Integrated population monitoring: detecting the effects of diverse changes. In:
R. W. Furness,
J. J. D. Greenwood
(eds). Birds as monitors of environmental change. Chapman, Hall, London, pp. 267–342. Google Scholar
R. D. Gregory
,
S. R. Baillie
1998. Large-scale habitat use of declining British birds: implications for conservation. J. Appl. Ecol. 35: 785–799. Google Scholar
R. D. Gregory
,
J. H. Marchant
1996. Population trends of jays, magpies and carrion crows in the United Kingdom. Bird Study 43: 28–37. Google Scholar
C. Harrison
1975. A field guide to the nest, eggs and nestlings of European birds. Collins, London. Google Scholar
J. R. Krebs,
J. D. Wilson,
R. B. Bradbury,
G. M. Siriwardena
1999. The second silent spring? Nature 400: 611–612. Google Scholar
J. H. Marchant
,
R. Hudson
,
S. P. Carter
,
P. Whittington
1990. Population trends in British breeding birds. British Trust for Ornithology, Thetford, Norfolk, UK. Google Scholar
P. McCullagh
,
J. A. Neider
1989. Generalized linear models. 2nd edition. Chapman & Hall, London. Google Scholar
J. A. Nelder
,
R. Mead
1965. A simplex method for function minimisation. Computer J. 7: 308– 313. Google Scholar
I. Newton
1999. An alternative approach to the measurement of seasonal trends in bird breeding success: a case study of the bullfinch Pyrrhula pyrrhula. J. Anim. Ecol. 68: 698–707. Google Scholar
W. H. Press
,
B. P. Flannery
,
S. A. Teukolsky
,
W. T. Vetterling
1989. Numerical recipes: the art of scientific computing (FORTRAN version). Cambridge University Press, Cambridge. Google Scholar
H. R. Pulliam
1988. Sources, sinks and population regulation. Am. Nat. 132: 652–661. Google Scholar
SAS Institute, Inc. 1996. SAS/STAT software: changes and enhancements through release 6.11. SAS Institute, Inc., Cary, NC. Google Scholar
J. T. R. Sharrock
1976. The atlas of breeding birds in Britain and Ireland. T & AD Poyser, Calton, Staffordshire. Google Scholar
G. M. Siriwardena
,
S. R. Baillie
,
S. T. Buckland
,
R. M. Fewster
,
J. H. Marchant
,
J. D. Wilson
1998a. Trends in the abundance of farmland birds: a quantitative comparison of smoothed Common Birds Census indices. J. Appl. Ecol. 35: 24–43. Google Scholar
G. M. Siriwardena
,
S. R. Baillie
,
H. Q. P. Crick
,
J. D. Wilson
2000a. Agricultural land-use and the spatial distribution of granivorous lowland farmland birds. Ecography 23: 702–719. Google Scholar
G. M. Siriwardena
,
S. R. Baillie
,
H. Q. P. Crick
,
J. D. Wilson
2000b. The importance of variation in the breeding performance of seed-eating birds for their population trends on farmland. J. Appl. Ecol. 37: 122–138. Google Scholar
G. M. Siriwardena
,
S. R. Baillie
,
H. Q. P. Crick
,
J. D. Wilson
2001. Changes in agricultural land-use and the breeding performance of granivorous farmland passerines. Agric. Ecosyst. Env. 84: 191–206. Google Scholar
G. M. Siriwardena
,
S. R. Baillie
,
J. D. Wilson
1998b. Variation in the survival rates of some British passerines with respect to their population trends on farmland. Bird Study 45: 276–292. Google Scholar
G. M. Siriwardena
,
S. R. Baillie
,
J. D. Wilson
1999. Temporal variation in the annual survival rates of six granivorous birds with contrasting population trends. Ibis 141: 621–636. Google Scholar
G. M. Siriwardena
,
H. Q. P. Crick
,
S. R. Baillie
,
J. D. Wilson
2000c. Agricultural habitat-type and the breeding performance of granivorous farmland birds. Bird Study 47: 66–81. Google Scholar
D. L. Thomson
,
R. E. Green
,
R. D. Gregory
,
S. R. Baillie
1998. The widespread declines of songbirds in rural Britain do not correlate with the spread of the avian predators. Proc. Roy. Soc. London B 265: 2057–2062. Google Scholar
UK Biodiversity Group 1998. Tranche 2 action plans: volume 1 — vertebrates and vascular plants. English Nature, Peterborough. Google Scholar
G. M. Tucker,
M. F. Heath
1994. Birds in Europe: their Conservation Status. BirdLife International, Cambridge (BirdLife International Series No. 3). Google Scholar
D. Vanhinsbergh
,
R. J. Fuller
,
D. G. Noble
2001. An analysis of changes in populations of British woodland birds 1966–1998 and a review of the possible causes. BTO Res. Rep. no. 245, Thetford, Norfolk, UK. Google Scholar
C. V. Wernham,
M. P. Toms,
J. H. Marchant,
J. A. Clark,
G. M. Siriwardena,
S. R. Baillie
, in press. The migration atlas: movements of the birds of Britain and Ireland. T & AD Poyser, London. Google Scholar

Acta Ornithologica
Vol. 36 • No. 2
December 2001
Vol. 36 • No. 2
December 2001
bird conservation
Bullfinch
demography
granivorous birds
population models
Pyrrhula pyrrhula