WILDLIFE WATCHING
In his series of great places to watch wildlife in the UK, the star of BBC One’s The One Show this month heads to our pebble-strewn shores to spot the species that thrive on shingle beaches.
Despite being tricky to walk on and nigh-on impossible to build a sandcastle from, shingle beaches are nevertheless a treasured and familiar part of the UK’s coast. On the worldwide stage, this habitat is also surprisingly rare. Away from the ‘shingle stronghold’ of north-west Europe, Japan and New Zealand are the only countries with large numbers of shingle beaches.
Ecologists classify shingle beach as being composed of deposited sediment ranging from 2mm to 200mm. This definition puts about 30 per cent of the UK’s coastline within this category. However, a significant proportion is composed of little more than simple fringing beaches within reach of powerful storm waves. At these sites, the constantly moving shingle means that colonising vegetation is unable to gain a foothold, ultimately resulting in a habitat of minimal interest to naturalists. It is generally only along the more extensive stretches – where perennial plants have begun stabilising the shingle – that the specialised invertebrates, birds and mammals so characteristic of this habitat are able to settle.
The most important shingle structures often take the form of spits, barriers or barrier islands, and tend to be produced by a process called ‘longshore drift’. This phenomenon, so beloved of A Level Geography students, occurs when waves approach the coastline from an angle, causing the movement of shingle in the same direction up the beach. As the retreating waves then carry the shingle back seawards, via the shortest route, this zig-zagging effect sees the incremental drift of material in one particular direction, leading to a small number of select sites accumulating vast banks of shingle.
On the seashore
The origin of this coastal shingle also varies according to the beach’s location. Certainly, in southern England, much of the shingle is composed of flint eroded from chalk cliffs. In northern and western Britain, shingle may have originated from deposits transported to the coast, either by rivers or as a result of glacial outwash.
The best shingle beaches for wildlife tend to have a distinct profile, with a seaward-facing beach often steeply rising to a ridge crest, which invariably drops off down a landward-facing ‘backslope’. The section closest to the sea is the most inhospitable environment, but even here, just beyond the highest tides, pioneer plants such as sea kale and yellow-horned poppy will soon proliferate, given the chance.
This broken terrain, consisting of clumps of hardy, drought-tolerant plants, is also frequently the strip used by coastal birds such as little tern, ringed plover and oystercatcher to hide their camouflaged clutches out in plain sight. On top of the ridge, and where soil is able to slowly accumulate, the vegetation is
Historically, the main damage to this habitat came from extraction of shingle to use in sea defences elsewhere.
characterised by a slightly different suite of halophytic (or salt-tolerant) plants, such as sea mayweed, sea campion and thrift. And finally, as the back-slope is usually more protected from the sea and the prevailing winds, a less specialised but generally more diverse vegetation begins to hold sway. Brackish lagoons are a common feature.
Unsurprisingly, the main threats to this specialised habitat come from humans, as feet and vehicles are capable of easily damaging the stabilising vegetation, while also causing disturbance during the birds’ breeding season. It is therefore important to keep to any designated footpaths and steer clear of cordoned-off areas throughout spring and summer.
Historically, the main damage to this habitat came from extraction of shingle to use in sea defences elsewhere, or as aggregate for the building industry. Today, we know more about the importance of vegetated shingle for rare and localised species – the real worry now is climate change. With sea levels projected to rise and storms increasing, this could see our shingle barricades battered or breached, as this most dynamic of habitats becomes a little too dynamic for comfort.