BREEDING BIRD COMMUNITIES AND ENVIRONMENTAL VARIABLE CORRELATES OF SCOTTISH PEATLAND WETLANDS

The majority of lochs and water courses in an area of northern Scotlan d were visited during July 1988. Breeding waterfowl and details of env ironmental variables were recorded for each site and subjected to mult ivariate classification techniques. Non-hierarchical classification id entified seven habitat types on the basis of environmental parameters. These corresponded well with, and further sub-divided, categorisation using conventional trophic-level habitat type classifications. A hier archical approach, using TWIN-SPAN, classified twelve waterfowl groupi ngs based on the presence of indicator species. This approach identifi ed characteristic community types and groupings with high diversity an d hence conservation importance. Correspondence between habitat classi fications and waterfowl communities was reasonable, but failure to ide ntify key features of wetland complexity was probably the reason for t he inability to identify clear relationships. Induction analysis was u sed to show that waterfowl species with the most restricted distributi ons characterised the main groupings, with Black-throated Diver and Co mmon Scoter showing preferences for mesotrophic/eutrophic waters with islands, where peaty waters drain onto base-rich sandy substrates. Gre ylag Geese occurred on large acidic oligotrophic lochs and Wigeon on b ase-rich streams. The need for catchment-wide site-safeguard and manag ement programmes to safeguard the wetlands of greatest significance is discussed.