Acid deposition :: Dipper

Latin name: 
Cinclus cinclus

Impact Type: Deposition of pollutant

Key Concerns:

Acidification affects birds primarily through their trophic dependence on prey. The dipper is largely dependent for its food on aquatic species such as mayfly, caddis larvae and fish which it finds in small, relatively fast flowing rivers. In habitats where Dipper territory coincides with freshwater acidification, there is a potential for adverse effects (Ormerod et al 1986, Ormerod 1991, Reynolds and Ormerod, 1991). These include:

  • Reduced population numbers and breeding success.
  • Deterioration in habitat quality.
  • Delayed laying.
  • Reduced clutch size, egg mass, brood size and nestling growth.
  • Reduced mass and condition in adults.
  • Reduced food sources.

These observations have been linked to decline in available prey and calcium intake in the diet of affected birds (Reynolds and Ormerod 1991). Later research by Ormerod & Rundle (1998) provided no support for effects of upland acidification on calcium availability to insectivorous terrestrial vertebrates. However, from the patterns found in eastern Scotland and elsewhere, it appears that the effects of acidity on Dipper populations are important generally, during both the breeding and non-breeding seasons (Logie 1995).

Additional Comments:

Dipper habitats have been studied in Wales and also in Scotland. It would be difficult to set a critical load for this habitat as the dose response linkage is between acid inputs, water chemistry and the abundance of invertebrates. However, work by Logie et al. (1996) suggests that critical load models may be generally applicable. Dipper populations can fluctuate greatly; studies of the population on the River Esk (Lothian, Scotland) have shown fluctuations of up to six fold over the last 60 years (Wilson 1996).

Critical Load/level: 
Critical Load/ Level

No estimate available

Logie, J.W. 1995 Effects of Stream Acidity on Non-Breeding Dippers Cinclus- Cinclus in the South-Central Highlands of Scotland Aquatic Conservation-Marine and Freshwater Ecosystems 5 25-35
Logie, J.W.; Bryant, D.M.; Howell, D. l; Vickery, J.A. 1996 Biological significance of UK critical load exceedance estimates for flowing waters: assessments of dipper Cinclus cinclus populations in Scotland Journal of Applied Ecology 33 1065-1076
Nybx, S.; Staurnes, M.; Erstad, K.J. 1997 Thinner eggshells of dipper (Cinclus cinclus) eggs from an acidified area compared to a non-acidified area in Norway Water, Air and Soil Pollution 93 255-266
Ormerod, S.J.; Wade, K.R.; Gee, A.S. 1987 Macro-floral assemblages in upland Welsh streams in relation to acidity and their importance to invertebrates. Freshwater Biology 18 545-557
Ormerod, S.J.; Woodin, (Eds) S.J.; Farmer, (Eds) A.M. 1991 The effects of acid deposition on nature conservation in Great Britain NCC Focus on Nature Conservation Report 26 p67-73
Raven, P.J.; Naura, M.; Holmes, N.T.H.; Dawson, F.H. 2000 Healthy river habitats fit for wildlife: Deriving the physical dimension. Journal of the Chartered Institution of Water and Environmental Management 14 235-239
Species group: 

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