Gavin Siriwardena


Head of Terrestrial Ecology & Principal Ecologist


Leads the BTO’s Land-Use Research team, which currently comprises up to 15 analytical and field research staff, conducting and supervising pure and applied research on terrestrial bird ecology.


BA Natural Sciences (Zoology), University of Cambridge 1990
PhD Aspects of Vocal Communication in the Carrion Crow, University of Leicester 1995

Research Interests / Responsibilities

Terrestrial bird ecology at a range of spatial scales, from territories to landscapes, via field experiments and analyses of large-scale, long-term datasets. Research at the BTO has considered migration ecology, cause of decline in woodland birds and methods of population trend analysis, but has focused primarily on farmland birds, contributing directly to government policy on the environment. A major three-year project on the demography of farmland birds (1996-1999), involving detailed analyses of extensive data sets held by the BTO and other organizations, helped to identify causes of decline. Subsequent large-scale projects have tested the hypotheses identified using landscape-scale field experiments and have also considered the likely efficacy of management solutions (2001-2007). More recently, research has focused on testing the agri-environment solutions to farmland bird conservation problems and on measuring the effects of current issues in farmland such as the disappearance of set-aside. A parallel research direction is considering bird-habitat modelling, considering both habitat types per se and habitat heterogeneity. Planned future research directions include further work on heterogeneity and habitat interactions, the ecology of predation and the design and testing of agri-environment solutions to the farmland bird conservation problems that still remain.

Other Information

Member of the Editorial Board of Bird Study.
Member of the British Ornithologists’ Union’s council.

Selected Publications

Plummer, K.E., Hale, J.D, O’Callaghan, M.J., Sadler, J.P., Siriwardena, G.M. 2016. Investigating the impact of street lighting changes on garden moth communities. Journal of Urban Ecology 1-10.

Plummer, K. E., Siriwardena, G. M., Conway, G. J., Risely, K. and Toms, M. P.  2015. Is supplementary feeding in gardens a driver of evolutionary change in a migratory bird species?. Global Change Biologydoi: 10.1111/gcb.13070

Oliver, T.H., Gillings, S., Girardello, M., Rapacciuolo, G., Brereton, T.M., Siriwardena, G.M., Roy, D.B., Pywell, R. & Fuller, R.J. 2012. Population density but not stability can be predicted
from species distribution models. Journal of Applied Ecology: doi: 10.1111/j.1365-2664.2012.02138.x

Siriwardena, G.M., Calbrade, N.A. & Vickery, J.A. 2008. Farmland birds and late winter food: does seed supply fail to meet demand? Ibis 150: 585–595.

Siriwardena, G.M., Stevens, D.K., Anderson, G.Q.A., Vickery, J.A., Calbrade, N.A. & Dodd, S. 2007. The effect of supplementary winter seed food on breeding populations of farmland birds: evidence from two large-scale experiments. Journal of Applied Ecology 44: 920-932.

Siriwardena, G.M. 2006. Avian nest predation, competition and the decline of British Marsh Tits Parus palustris. Ibis 148: 255-265.

Siriwardena, G.M., Calbrade, N.A., Vickery, J.A. & Sutherland, W.J. 2006, The effect of the spatial distribution of winter seed food resources on their use by farmland birds. Journal of Applied Ecology 43: 628-639.

Cowley, E. & Siriwardena, G.M. 2005. Long-term variation in survival rates of Sand Martins Riparia riparia: dependence on breeding and wintering ground weather, age and sex, and their population consequences. Bird Study 52: 237-251.

Siriwardena, G.M. 2004. Possible roles of habitat, competition and avian nest predation in the decline of the Willow Tit Parus montanus in Britain. Bird Study 51: 193–202. 

Siriwardena, G.M., Wernham, D.V., & Baillie, S.R. 2004. Quantifying variation in migratory strategies using ring-recoveries. Animal Biodiversity and Conservation 27: 299-317. 

Wernham, C.V., Toms, M.P., Marchant, J.H., Clark, J.A., Siriwardena, G.M. & Baillie, S.R. (eds) 2002. The Migration Atlas: movements of the birds of Britain and Ireland. T. & A.D. Poyser, London.

Siriwardena, G.M., Baillie, S.R., Crick, H.Q.P. & Wilson, J.D. 2000. Agricultural land-use and the spatial distribution of granivorous lowland farmland birds. Ecography 23: 702-719.

Siriwardena, G.M., Baillie, S.R., Crick, H.Q.P. & Wilson, J.D. 2000. The importance of variation in the breeding performance of seed-eating birds for their population trends on farmland. Journal of Applied Ecology 37: 1-22.

Siriwardena, G.M., Baillie, S.R., Crick, H.Q.P., Wilson, J.D. & Gates S. 2000. The demography of lowland farmland birds. Proceedings of 1999 BOU Conference: Lowland Farmland Birds. Pp 117-138. BOU, Tring.

Krebs, J.R., Wilson, J.D., Bradbury, R.B. & Siriwardena, G.M. 1999. The second silent spring? Nature 400: 611-612.

Peach, W.J., Siriwardena, G.M. & Gregory, R.D. 1999. Long-term changes in the abundance and demography of British reed buntings Emberiza schoeniclus. Journal of Applied Ecology 36: 798-811. 

Siriwardena, G.M., Baillie, S.R. & Wilson, J.D. 1999. Temporal variation in the annual survival rates of six granivorous birds with contrasting population trends. Ibis 141: 621-636. 

Siriwardena, G.M., Baillie, S.R. & Wilson, J.D. 1998. Variation in the survival rates of British farmland passerines with respect to their population trends. Bird Study 45: 276-292. 

Siriwardena, G.M., Baillie, S.R., Buckland, S.T., Fewster, R.M., Marchant, J.H. & Wilson, J.D. 1998. Trends in the abundance of farmland birds: a quantitative comparison of smoothed Common Birds Census indices. Journal of Applied Ecology 35: 24-43.

Contact details

Email: gavin.siriwardena [at]
Telephone: 01842 750050
Fax: 01842 750030
Postal address: British Trust for Ornithology, The Nunnery, Thetford, IP24 2PU, UK.