Habitat change and loss represent major threats to the conservation of waterbirds worldwide. On estuaries, for example, large areas of intertidal mudflats and saltmarsh have been lost to land-claim for industry, housing, harbour developments and remaining habitat is now threatened by sea-level rise.

The Wetland and Coastal Ecology Unit has undertaken a range of research projects, using both existing WeBS data and data collected specifically for the projects, that have aimed to predict or evaluate the possible impacts on waterbirds of such changes. Key project areas are summarised below.

Predictive studies

Collaborative work with the Centre for Ecology and Hydrology (CEH) developed models which allow estuarine waterbird densities to be predicted country-wide from a suite of environmental variables (Austin et al. 1995, Holloway et al. 1995). These models can be used to predict the likely impact on waterbird populations of habitat change due to natural factors, climate change or human developments (Rehfisch et al. 1999, 2000). As part of the “Modelling Natural Resource Responses to Climatic Change” project (MONARCH) the models developed with CEH were used to predict waterbird populations on a range of estuaries for different scenarios of sea-level rise and taking into account various options for hard sea defences and managed realignment (Austin et al. 2001, Austin & Rehfisch 2003).

WeBS and other BTO survey data are also frequently used for impact assessment work and were used, for example, to predict the potential safety risks from birds at a potential new airport at Cliffe Marshes in Kent (Bell et al. 2003). Publications.

Habitat Loss

The impacts on waterbirds of the loss of intertidal habitat were the subject of a long-term study at Cardiff Bay (Burton 2006). Here, a barrage development led to the displacement of several hundred estuarine waterbirds in 1999. Pre-barrage monitoring of marked individuals of a focal species, the Redshank, provided valuable baseline information on the site-fidelity and site use of this species (Burton 2000,
Burton & Armitage 2005). Post-barrage, redshank displaced from Cardiff Bay to a neighbouring estuary experienced poor body condition and a significant increase in mortality rate (Burton et al. 2006).

Habitat Creation

The loss of intertidal habitats to sea-level rise has been the subject of much recent concern. To counter these losses, a number of management responses have been suggested, including ‘holding the line’ through engineering techniques, abandonment or managed realignment - allowing the sea to penetrate sea walls and create new intertidal habitats (Atkinson et al. 2004). The BTO has provided a review of the success of the first managed realignment schemes in the country for English Nature Atkinson et al. 2001. Publications

Water quality

Coastal sewage outfalls may provide considerable supplies of food for bird species, either as directly edible matter or by artificially enhancing concentrations of invertebrate food through nutrient enrichment. Work has reviewed the possible impacts on waterbirds of recent programmes of improvements to sewage treatment and discharge (Burton et al. 2002a) and assessed whether waterbird trends on English and Welsh SPAs might correlate with changes in water quality (Burton et al. 2004).

A recent field project has also investigated the improvements to sewage discharges on Turnstones and Purple Sandpipers wintering on the Northumberland coast, using count data and individual colour-marking (Burton et al. 2005). The potential for waterbirds to also impact water quality themselves, through faecal contamination, was the subject of a detailed two year study at Blackpool (Wither et al. 2005). Publications.

Disturbance

The waterbirds that winter in the United Kingdom can face intense pressure from human disturbance (from, for example, construction work, traffic and recreation) as a result of the high urbanization found at many coastal and freshwater sites. The effects (behavioural responses) and impacts (on waterbird fitness and populations) of disturbance have thus been the subject of considerable study. Studies using data from the WeBS Low Tide scheme and Cardiff Bay work aimed to evaluate possible changes of distribution resulting from disturbance using a landscape approach, in which the presence of features in the landscape associated with disturbance as a surrogate (Burton et al. 2002b 2002c; Burton 2007).

Further studies have assessed how disturbance-free high tide refuges on the Wash and Moray Firth should be distributed to optimise wader usage and have thus formed the basis for understanding the likely impacts of habitat loss (Rehfisch et al. 1996, 2003). Publications

Publications

Predictive Studies

Austin, G. & Rehfisch, M.M. (2003). The likely impact of sea level rise on waders (Charadrii) wintering on estuaries. Journal for Nature Conservation, 11, 43-58.

Austin, G., Rehfisch, M.M., Holloway, S.J., Clark, N.A., Yates, M.G., Clarke, R.T., Goss-Custard, J.D. (1995). Estuary, sediments and shorebirds III. Predicting waterfowl densities on intertidal areas. BTO Research Report No. 160 to ETSU.

Austin, G.E., Rehfisch, M.M., Viles, H.A., & Berry, P.M. (2001). Impacts on coastal environments. pp. 177-228 In: Harrison, P.A., Berry, P.M. & Dawson, T.P. (Eds.) Climate Change and Nature Conservation in Britain and Ireland - modelling natural resource responses to climate change (the MONARCH project). UKCIP Technical Report, Oxford.

Bell, J.C., Burton, N.H.K., Walls, R., Musgrove, A.J., Allan, J.R., Rehfisch, M.M. & Watola, G. (2003). Study on the potential safety risks from birds at and around a potential new airport at Cliffe Marshes and measures for mitigating those risks. Report by the Birdstrike Avoidance Team, Central Science Laboratory and British Trust for Ornithology to the Department for Transport. Department for Transport, London.

Holloway, S.J., Rehfisch, M.M., Clark, N.A., Austin, G., Yates, M.G., Clarke, R.T., Goss-Custard, J.D. et al. (1995). Estuary, sediments and shorebirds II. Shorebird usage of intertidal areas. BTO Research Report No. 156 to ETSU.

Rehfisch, M.M., Austin, G.E., Clark, N.A., Clarke R.T., Holloway, S.J., Yates, M.G., Durell, S.E.A. le V. dit, Eastwood, J.A., Goss-Custard, J.D., Swetnam, R.D. & West, J.R. (2000). Predicting densities of wintering Redshank Tringa totanus from estuary characteristics: a method for assessing the likely impact of habitat change. Acta Ornithologica, 35, 25-32.

Rehfisch, M.M., Holloway, S.J., Yates, M.G., Clarke, R.T., Austin, G., Clark, N.A., Durell, S.E.A., le V. dit, Eastwood, J.A., Goss-Custard, J.D., Swetnam, R.D. & West, J.R. (1999). Predicting the effect of habitat change on waterfowl communities: a novel empirical approach. In: Predicting Habitat Loss (ed. J. Goss-Custard, R. Rufino & A. Luis), pp. 116-126. HMSO, London.

Habitat Loss

Burton, N.H.K. (2000). Winter site-fidelity and survival of Redshank Tringa totanus at Cardiff, south Wales. Bird Study, 47, 102-112.

Burton, N.H.K. (2006). The impact of the Cardiff Bay barrage on wintering waterbirds. Proceedings of the Waterbirds Around the World Conference.

Burton, N.H.K. & Armitage, M.J.S. (2005). Differences in the diurnal and nocturnal use of intertidal feeding grounds by Redshank Tringa totanus. Bird Study, 52, 120-128.

Burton, N.H.K., Rehfisch, M.M., Clark, N.A. & Dodd, S.G. (2006). Impacts of sudden winter habitat loss on the body condition and survival of redshank Tringa totanus. Journal of Applied Ecology, 43, 464-473.

Goss-Custard, J.D. Burton, N.H.K., Clark, N.A., Ferns, P.N., McGrorty, S., Reading, C.J., Rehfisch, M.M., Stillman, R.A., Townend, I., West, A.D. & Worrall, D.H. (2006). Test of a behavior-based individual-based model: response of shorebird mortality to habitat loss. Ecological Applications.

Habitat Creation

Atkinson, P.W., Crooks, S., Drewitt, A., Grant, A., Rehfisch, M.M., Sharpe, J. & Tyas, C. (2004). Managed realignment in the UK - the first five years of colonisation by birds. Ibis, 146, S101-S110.

Atkinson, P., Crooks, S., Grant, A. & Rehfisch, M.M. (2001). The success of creation and restoration schemes in producing intertidal habitat suitable for waterbirds. English Nature Research Reports. English Nature, Peterborough.

Water Quality

Burton, N.H.K., Fuller, R.A. & Eaton, M.A. (2005). Between-year changes in the wintering sites of Ruddy Turnstones Arenaria interpres: a response to diminished food resources? Wader Study Group Bulletin, 107, 36-39.

Burton, N.H.K., Jones, T.E., Austin, G.E., Watt, G.A., Rehfisch, M.M. & Hutchings, C.J. (2004). Effects of reductions in organic and nutrient loading on bird populations in estuaries and coastal waters of England and Wales. Phase 2 Report. EN Research Report 586. ISSN 0967-876X. English Nature, Peterborough, U.K.

Burton, N.H.K., Paipai, E., Armitage, M.J.S., Maskell, J.M., Jones, E.T., Struve, J., Hutchings, C.J. & Rehfisch, M.M. (2002a). Effects of reductions in organic and nutrient loading on bird populations in estuaries and coastal waters of England and Wales. Phase 1 Report. BTO Research Report No. 267 to English Nature, the Countryside Council for Wales and the Environment Agency. BTO, Thetford.

Wither, A., Rehfisch, M. & Austin, G. (2005). The impact of bird populations on the microbiological quality of bathing waters. Water Science & Technology, 51, 199-207.

Disturbance

Burton, N.H.K. (2007) Landscape approaches to studying the effects of disturbance on waterbirds. Ibis, 149 (Suppl. 1), 95-101

Burton, N.H.K., Armitage, M.J.S., Musgrove, A.J. & Rehfisch, M.M. (2002b). Impacts of man-made landscape features on the numbers of estuarine waterbirds at low tide. Environmental Management, 30, 857-864.

Burton, N.H.K., Rehfisch, M.M. & Clark, N.A. (2002c). Impacts of disturbance from construction work on densities and feeding behavior of waterbirds using the intertidal mudflats of Cardiff Bay, UK. Environmental Management, 30, 865-871.

Rehfisch, M.M., Clark, N.A., Langston, R.H.W. & Greenwood, J.J.D. (1996). A guide to the provision of refuges for waders: an analysis of thirty years of ringing data from the Wash, England. Journal of Applied Ecology, 33, 673-687.

Rehfisch, M.M., Insley, H. & Swann, B. (2003). Fidelity of overwintering shorebirds to roosts on the Moray Basin, Scotland: implications for predicting impacts of habitat loss. Ardea, 91, 53-70.