Anger is growing among conservationists in Cornwall after birds were "flushed" from nature reserves by low-flying naval helicopters.
Bird-watchers have bombarded the RSPB with reports of Sea King helicopters disturbing flocks at Hayle Estuary. The charity says repeated sorties by aircraft from RNAS Culdrose over marshland at Marazion has also driven away all but two breeding pairs of grey herons, the only ground-nesting examples of the species in the country.
Both sites enjoy protected status as Sites of Special Scientific Interest (SSSI).
Dave Flumm, site manager for Cornwall reserves, said the helicopters were scattering thousands of birds from the sanctuaries.
"There were seven pairs of grey heron nesting in the reed beds at Marazion initially, but a local birder saw them flushed and any eggs would have literally frozen in these conditions," Mr Flumm said. "We were told they need to use the route for low-flying sorties in bad weather, but it is becoming a regular thing, even on clear sunny days.
"This is a critical time of year for breeding and for birds who need to build up fat reserves but it is also an economic issue as we are a hotspot for birders and people are becoming quite heated and fed up."
Hayle estuary, the most south-westerly in the UK, never freezes and can attract as many as 18,000 birds, including migrant waders, gulls, terns and even osprey. It attracts bird-watchers with a number of other "star species" such as curlew, little egret, oystercatcher and wigeon.
The RSPB, which manages the reserve, wrote to RNAS Culdrose last year and Natural England contacted the base recently about the issue. They have complained that crews fly in from the sea and either track the Hayle river back to the air base or follow the main railway line down to Mounts Bay before turning east towards the headquarters, near Helston.
The Royal Navy base has both the Merlin helicopter, which is used principally as a submarine hunter out at sea, and the Sea King, which is often called in as assistance during an emergency.
A spokesman for the base said the Merlin would not fly low and the Sea King would do so only in poor weather or when conducting a search and rescue operation. "Crews are quite dutiful in what they do," he added. "We are aware and do try to avoid as much as possible – SSSIs are broadcast to squadrons and are on maps and they know it is an 'avoid'. They tend to steer well clear of wildlife areas anyway as birds can fly up into the aircraft."
