Exploring Coastal Conservation at RSPB Culbin Sands Nature Reserve (Indoor Meeting, January 25th 2024)

 

Steph Elliot and David Tompkins gave a very informative talk on the origin and ecology of a local landmark, and the steps which are being taken to preserve it for the species whose home it is.  

RSPB Culbin Sands reserve extends from Nairn’s East Beach to the west side of the mouth of the River Findhorn. As the name indicates, it consists of the area between the high and low tide lines – the intertidal zone. Culbin Forest, although it is also rich in wildlife, is not part of the reserve. 

The area is of international importance, with five conservation designations: 

  •  a UK Site of Special Scientific Interest 
  •  a Special Protection Area 
  •  a Special Area of Conservation 
  •  a RAMSAR site; and 
  •  a Geological Conservation Review site. 

There are four main coastal habitats: the intertidal sand- and mudflats, sand dunes, shingle and saltmarsh.  The intertidal zone offers enormous feeding opportunities for many species of birds. Waders such as Redshank, Curlew, Dunlin, Bar-tailed Godwit, Snipe, Oystercatcher, Sanderling and Knot all feed on the invertebrates found in the sand and mud. The two species of eel-grass – Common and Dwarf – are a major attraction for Brent Geese. The mussel beds here are so important for seaducks that the RSPB has bought the mussel-fishing rights all along this stretch of coast to protect this food source. 

The Culbin Bar is a shingle bank about 7km long. Steph showed a map which illustrates how the whole 7km has been laid down over the past 400 years. She explained how the interaction of wind and tides, shifting and depositing material, means that the bar is constantly moving westward but that its westernmost point is also pushed back towards the shore by the tides and northerly winds, creating a pattern which, from the air, resembles outstretched fingers. In between these are sheltered lagoons. The saltmarsh, which is mainly found closest to the shore, develops because the Bar and dunes protect this area from the worst impact of tides and storms. However, this remarkable collection of habitats, and all the complex interactions which sustain them, are under threat. 

At this point, Steph handed over to David to describe the threat and what is being done to counteract it. He began by showing a series of aerial photographs of Culbin, taken between 1959 and 2022. These illustrated both how far the Bar has moved westward in this time, and the change in its vegetation. 

The flora of the Bar, for which it is internationally recognised – species such as heathers, Crowberry and Juniper – have been invaded by “woody scrub” species such as Scots Pine and Broom. The same has happened to the dune ridges, where these species have emerged among Marram grass, the typical dune vegetation. This woody scrub, if it became too well-established, would stabilise the shingle, threatening the dynamic and ever-changing nature of the Bar and the reserve as a whole. It also creates too much shade for some of the sun-loving plants of the area to thrive, plants such as heathers, which are an important food source for bees, and Kidney Vetch, which is the sole food eaten by the caterpillars of the Small Blue butterfly, a species rapidly declining in Scotland.  

However, this colonisation of the Bar and dunes only began relatively recently, in the last 15-20 years. If the woody scrub plants had become established on the shingle bank at other times in the past three or four centuries, then its westward drift would surely have been halted long ago. David offered a suggestion about what might have contributed to the current predominance of scrub – a scarcity of rabbits, which would normally eat the young shoots of these invasive species! He showed graphs from several different scientific papers illustrating the decline in the numbers of rabbits, first with the deliberate introduction of myxomatosis in the 1950s, and again from the mid-1990s.  

However, with much work from RSPB staff and volunteers, real headway has been made in the restoration of the dune and shingle bar systems. Just as the relative remoteness of the site has protected it from some of the human disturbance that has badly affected similar sites elsewhere in the UK, it makes getting there to do the necessary work difficult: David showed us a photo of volunteers heading out to the Bar in dinghies with outboard motors, rather than making the long trek along it from its eastern end. The nature of the site means that heavy machinery can’t be used in restoration work – it all has to be done with hand-held tools. Members of work parties use strimmers, chainsaws and tree poppers to control and remove scrub. This effort is paying off. Finally, before-and-after photos gave us a clear idea of how much work had been done, and what a difference it had made.