Dippers (Cinclus cinclus) as bioindicators of health and resilience of freshwater ecosystems in the face of complex ecological change

We are seeking a highly motivated individual to undertake research focussing on understanding on river bird responses to environmental change in Britain.

Freshwater ecosystems are of critical importance because they integrate effects of environmental pressures across landscapes and catchments and are more than twice as important as other broad habitat types in terms of ecosystem service delivery per unit area (Natural Capital Asset Index). Monitoring freshwaters effectively and understanding their response to multiple environmental stressors is, however, challenging.

Dippers are the quintessential river bird of Britain and, as a predator, are likely to provide a convenient and effective sentinel of the health of our riverine ecosystems and their response to various forms of environmental management. Dippers are proven sensitive indicators of anthropogenic pressures such as acidification from air pollution. However, in the past 30 years, acid deposition has declined greatly following controls on emissions, while more environmentally benign forestry practices have mitigated impacts of conifer plantations on upland stream acidification. Water pollution from industrial and urban point sources has also been strictly regulated leading to improved water quality. The declines in dipper populations, and those of some other riparian birds revealed by Bird Atlas 2007-11, are therefore a conundrum.

Dippers are predicted to be highly responsive to changes in temperature and flow regimes arising from climate change. While Dippers are adversely affected by severe winters these have been eclipsed by mild wet winters in recent decades which are reflected in overall increases in river flow and variability, most notably in the west of the country. Water colour is generally increasing (‘brownification’) in upland freshwaters as the constraints of acidification on decomposition rates and solubility of organic carbon are lifted, alongside increasing precipitation and temperature. There is a growing case that effects of more variable river flow regimes and increased water colour on aquatic invertebrate prey and Dipper foraging efficiency may be affecting Dipper demographic rates and thus contributing to declines in this and other river birds.

The overall aim of the project is to understand the environmental basis for spatial and temporal changes in Dipper distribution and breeding densities and how these reflect local and catchment level influences versus climatic factors. Specific objectives are to (i) Determine the level of Dipper population recovery in known acidification hotspots in Scotland based on repeating surveys undertaken in the late 1980s and compare this with trends on catchments unaffected by acidification (ii) Identify if flow, stream colour and invertebrate prey densities are important predictors of spatial and temporal variation in Dipper foraging efficiency and breeding success and (iii) Model correlates of long-term Dipper population change at regional and national scales and identify aspects of current catchment management that may improve long term performance.

Scotland has a rich archive of detailed climate projections, land cover maps, recent management histories, and high quality historical and current data on river flow, chemistry and invertebrate populations. Combined with the multiple detailed historical studies of Dipper ecology and demography from different parts of the country this provides a unique opportunity to test how the changing balance of environmental pressures on freshwaters impacts a charismatic and accessible bio-indicator species. It also presents an opportunity to explore if various local and catchment scale management interventions, ultimately intended to benefit biodiversity and ecosystem service delivery, lead to improved Dipper performance. The student will also benefit from co-supervision by conservation science specialists from RSPB (Professor Jeremy Wilson & Dr Juliet Vickery), GIS specialists at CEH (Phil Taylor) and CASE funding provided by SNH.

Applicants for this project must have a first class or upper second class Honours degree and/or a relevant postgraduate degree, in either biological/environmental sciences, ecology or related disciplines. Applicants must be able to drive and willing to undertake extensive periods of fieldwork. An interest in birds, freshwater ecology, conservation management and environmental change is highly desirable.