Situated off Scotland's northwest coast lies an archipelago of about 120 islands known as the Outer Hebrides. Most of these islands comprise a bedrock of Lewisian gneiss, formed in the Precambrian period up to three billion years ago, making them among the oldest rocks in Europe. While this igneous stratum has been virtually impenetrable to the forces of sea and gale over many millennia, there also exists on the same island chain a far more delicate and fragile geological form known by the local Gaelic-speakers as machair.
Found only in the northwest of Great Britain and Ireland, machair is a coastal dune plain of shell-derived sand that today supports pasture and wildflowers. Although the name is derived from the Gaelic, meaning low-lying fertile plain, machair is now a recognised scientific and ecological term for this unique and scarce coastal feature, which is also one of the rarest habitats in Europe.
About half of Scotland's machair is found in the Outer Hebrides. The most extensive areas occur on the west coasts of North and South Uist, Barra and Tiree four of the 15 populated islands that make up this remote corner of the British Isles. Ecologists believe that the impact of human settlement, notably through the methods used to cultivate the land through many centuries, has contributed to the unique characteristics of machair.
Machair flourishes because of a special blend of lime-rich shell sand (which is blown inland by the strong Atlantic winds), acidic peaty soil, seaweed used by crofters to fertilise their fields and frequent rainfall.
Machair supports numerous plant and bird species that are rare or non-existent on the British mainland. As a result, this scarce habitat is recognised as an environmentally sensitive area (ESA); a list of recommended cultivation practices and techniques has been created in order to aid its preservation.
Many of the islanders who till this fertile strip of land are crofters--owners or tenants of small landholdings who work the land for crops and livestock, often in exactly the same way as their ancestors. The ESA recommendations reflect these traditional practices, which include delaying the cutting of hay until August and cutting from the centre of the field outwards to enable birds such as corncrakes to escape to neighbouring fields.
The Outer Hebrides is one of the last strongholds of the corncrake, which has become increasingly scarce on the British mainland because of intensive agriculture. It arrives from Africa in May and seeks the cover of hayfields to nest.
Other rare mainland birds that still thrive on the cultivated machair include the corn bunting, twite and little tern.
However, it's the waders that are most commonly seen here during the summer months, when an estimated 25,000 breeding pairs of lapwing, dunlin, ringed plover and oystercatchers attract birdwatchers and photographers in equal measure. Ringed plovers and oystercatchers are most dependent upon crofting practices, as they both prefer to nest on dry cultivated machair.
As autumn approaches, ESA recommendations mean that corn cutting is delayed until September (sometimes into early October) in order to allow wildflowers to set seed. The Outer Hebrides is one of the last places where corn can still be seen tied into sheaves, simply because the fields of North and South Uist, Tiree and Barra are too small for binders and balers. The stubble left after cropping is a favourite food for migratory barnacle and white-fronted geese, as well as whooper swans, which arrive on these shores from late October.
It's this harmonious co-existence of traditional methods of cultivation and land use with the lifecycles of flora and fauna that ensures that the machair of the Outer Hebrides maintains a rich biodiversity. For example, crofters must complete sowing and harrowing of their fields by mid-May in order to allow ringed plover and oystercatchers to nest on bare ground after ploughing.
Wildflowers, too, are helped by the ESA guidelines, as well as local regulations, most notably in South Uist, where livestock isn't permitted to graze in unfenced areas from early May. During summer, common crops such as rye and oats are interspersed with a patchwork of colourful wildflowers that reach their peak in July and early August. This rich variety of plant species on fairly small landholdings attracts a wide range of pollinating insects and other invertebrates, which in turn provides birds with plenty of food and the perfect conditions to stay and breed.
It's on these ploughed lands that the best displays of machair wildflowers can be seen for a few weeks at the height of summer. The types of flowers varies from island to island. For example, bluebells and red clover are a prime feature of the machair around Scarista, on the Isle of Harris; self-heal prunella abounds on the machair of Tolsta on the Isle of Lewis; and pink thrift and yellow birds foot trefoil are common sights on Great Bernera. Wild orchids to look out for include the heath orchid and Hebridean spotted orchid.
Other common machair flowers include daisies and buttercups, knapweed, harebell, centaury and butterwort. These flowers aren't distributed evenly across the islands. In fact, the actual flowers present on any patch of machair will vary according to the blend of shell sand and peat, which in turn affect the acidity of the soil. For example, the greater the level of peat, the more likely it is that acid-tolerant plants and flowers, such as heather, sundew, cotton grass and milkwort, will be found.
LOCATION AND LENSES
With so many species of bird, plant and insect occupying a small area of isolated and unspoilt coastline, there's plenty of potential for the nature photographer in the machair of the Outer Hebrides. Choosing which subjects to photograph depends very much on the time of year.
This will also determine the choice of lenses: a mid-summer visit when the machair is at its colourful best will require macro lenses for close-ups of the flowers and rare insects such as the great yellow bumblebee. When making close-up studies, wait for any breeze to drop before pressing the shutter so as to reduce the risk of any subject movement during exposure (unless of course some creative blur to depict wildflowers blowing on a breezy day is your intention).
A wide-angle lens is also recommended to compose the broad sweep of wildflowers filling the foreground against a background of blue sea and sky. For such an image it's important not to let the exposure reading be influenced by too much sky in the scene: far better to meter from the grasses and other plants in the foreground, lock this reading, and then recompose.
Birdwatchers favour prime or zoom telephoto lenses to seek out elusive species such as the corncrake or corn bunting, which remain well camouflaged until the crops are harvested in September. For this reason, this month has the potential to provide the greatest variety of picture opportunities: to catch the last of the wildflowers before cropping and the thousands of wading birds before they head south to escape the onset of winter. As with any animal portrait, it's the eye of the bird that should be the primary point of focus.
By late October, the days are brief, grey and windy, but the wildlife photographer can look forward to focusing on the snowy white plumage of hundreds of whooper swans migrating south from Iceland. Photographing these large birds, along with the resident greylag geese and migratory white-fronted and barnacle geese, demands long-focal-length lenses supported by tripods or beanbags to prevent any vibration or movement during exposure.
The composition and existence of the machair has been determined by a fine balance of natural forces, local geology and human impact. But it remains a fragile existence. Ecologists believe that this small and unique ecosystem could disappear quickly if this fine balance is disrupted.
The machair lies close to the sea; it's lashed by fierce gales from the west. As a result, it's particularly vulnerable to climate change and rising sea levels. A more volatile climate resulting in greater amounts of shell sand blowing inland, or a rise in salinity of sand and peat, could degrade the fertility of the machair's thin layer of soil, and with it, change the rich biodiversity of this marginal land forever.
Use a tripod and weigh it down further with stones or other heavy items to keep it steady in strong winds. If using an image-stabilising lens, remember to switch it on!
Take a spot meter reading from a mid-tone. Most flowers, grass and crops are suitable for mid-tones, but green grass is by far the best
Use a polarising filter to reduce the glare from the surface of the sea in the background. Also take a neutral density graduated filter to reduce the contrast when the sky is bright
Leave your camera and lenses exposed to the salt air or near sand when not in use.
The former is corrosive, the latter a killer to the internal workings of camera and lens
Use flash when photographing flowers.
All plants look far more natural when photographed in daylight. If you want to fill-in shadows, use a reflector
Trespass. Crofts may be small landholdings, but they're someone's livelihood. Permission should be sought before entering a field, unless there's a clearly marked public right of way
From Machair to Mountains: Archaeological Survey and Excavation in South Uist by Michael Parker Pearson, Oxbow Books, hb, 35 [pounds sterling]
The Outer Hebrides: Moor and Machair by Stewart Angus, Whitehorse Press, hb, 50 [pounds sterling]
The Outer Hebrides by Malcolm MacGregor, Frances Lincoln, hb, 30 [pounds sterling]