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The word ‘machair’ comes from Gaelic and means an extensive low-lying and fertile plain. The term for this habitat encompasses everything from their white sandy beaches, to the calcium-rich dune pasture, to where the sand encroaches on to the peatlands further inland. Taking a walk along the machair in spring when the birds are calling, or in summer when there is the most incredible blaze of wild flowers is like taking a step back to the halcyon pre-industrialised days of farming on mainland Britain.

Machair

WHEN

Late May to August

WHERE

West coast of the Outer Hebrides, Tiree, Coll and other small Scottish beaches with a westerly aspect

The floral extravaganza that is the machair.

Bob Gibbons

With its precise requirements for formation and its localised nature, machair is one of the rarest habitats in Europe. In the British Isles, it is found only in the north and west of Scotland and western Ireland, of which almost half occurs along virtually the entire western fringe of the Outer Hebrides. The machair habitat as we know it today was formed at the end of the last Ice age after the melt water from the glaciers deposited enormous quantities of sand and gravel into the sea over what is now the Continental shelf. As the sea level rose, this glacial sediment, which became mixed with the crushed shells from marine molluscs, was then driven ashore by waves from the strong prevailing southwesterly winds to form the characteristic white beaches. Over time a constant supply of this sand caused some to be blown above the high-tide mark and began the formation of dunes. Centuries of constant wind has occasionally broken down these dunes, depositing this fine white sand on to the fields and pastures beyond, even blowing far enough inland to coat some of the peat bogs.

As machair sand is composed of 80 to 90 per cent crushed shells, these western beaches are white in colour, as opposed to the more typically yellow-coloured beaches on the eastern coasts of outer Hebridean islands, such as North Uist, where the sand is mostly from mineral-based material. Down below the sea line on beaches with a westerly aspect, the sand is repeatedly exposed to the action of the waves and wind meaning it is a highly mobile environment and devoid of any colonising plants, but just above the high-tide line the first few hardy, pioneering plants like sea rocket and sea sandwort begin to take hold. The very presence of these plants initiates the eventual formation of dunes: they provide a barrier to sand particles which then become deposited, and in turn create a bigger obstacle as more sand becomes accumulated by the plants as it is blown up the beach. The number one dune builder has to be marram grass, as its spiky inwardly rolled leaves, rapid growth rate, tussocky nature and deep root system mean that it can thrive in this harsh, sandblasted environment.

Behind these dunes – which can reach up to ten metres in height – the impact of the wind and salt spray are much reduced, meaning that a larger variety of plants are able to grow in the bare sand. As these plants decay over the seasons, the embryonic soil holds moisture a little more easily and the alkalinity is slightly lowered, meaning that plants such as butter-cups and lady’s bedstraw may be able to take hold, eventually forming meadows as the sand becomes habitable.

From the end of autumn until at least the middle of May, the machair has been described as a ‘desolate waste of sand’, but equally large areas of the machair can be flooded. This serves to protect these vulnerable grasslands from wind erosion and to provide rich feeding grounds for wintering wildfowl such as barnacle and Greenland white-fronted geese. Atlantic winter storms wash up a huge amount of kelp from just offshore and this forms an additional sea wall along the dune edge, which helps to protect the machair from being inundated by sea water. This kelp, or ‘tangle’, has been collected by the local population ever since Neolithic times as a natural fertiliser and 40 tonnes per hectare is still placed over the machair once it has drained each spring to improve the organic content. The fields are then ploughed to help bind the soil together and to improve its moisture-holding capacity, which in turn makes the grassland more resistant to wind erosion and ready for planting crops.

The corncrake, a.k.a. Crex crex. So repetitive they named it twice!

Derek Middleton

Spring generally arrives late on the machair because of cold easterly winds, but the application of the tangle, the ploughing, and careful grazing before the main growing season help create the perfect conditions for a vast array of wild flowers to grow alongside the planted oats, rye or barley crops. Strict field rotation is practised and, in some of the fallow areas, the floral diversity is so rich that it can reach an astonishing 45 species per square metre.

Early in the season the white confetti of daisies cover huge areas of machair; come June, the machair turns yellow as buttercups and bird’s-foot trefoil dominate in the drier areas, and silverweed, yellow rattle and marsh marigold thrive on the slightly wetter ground. Later in the summer the predominant colour tends to move to the red and purple end of the spectrum with red clover, ragged robin, self-heal and field scabious taking centre stage. The machair is also famous for its orchids, with pyramidal and fragrant orchids occurring in profusion alongside the unique Scottish marsh orchid at a number of sites on North Uist. The application of very low concentrations of herbicides means that, growing among the crops to be harvested, agricultural weeds, such as corn marigold and charlock that are all but extinct on the mainland, can be found.

This phenomenal floral diversity provides food and accommodation for a wide variety of invertebrates such as snails, grasshoppers, spiders, harvestmen and rare bumblebees, which, in turn, provide food for a range of agricultural birds that have declined massively on mainland Britain but of which the Outer Hebrides still have healthy populations. The machair and adjacent crofting lands on the Inner and Outer Hebrides have now become the last remaining strongholds of the corncrake, with recent surveys indicating that the islands may well hold at least 90 per cent of the British population of just under 600 calling males. This notorious skulker was difficult to see even in its heyday, when it could be heard repeating its strange rasping call up to 20,000 times a night all over rural Britain. Looking rather like a cross between a grey and rusty-coloured chicken and a moorhen, the corncrake began to decline on mainland Britain at the turn of the 20th century because of agricultural intensification. As hay fields were cut mechanically, the grass was cut earlier and removed for silage in early summer, the nests, young and even the adults disappeared rapidly. However, late cutting and the low-level of mechanisation is still commonplace in the Outer Hebrides today, which allows the corncrakes to hide in plentiful cover at harvest time, giving them a fighting chance. Grants and subsidies in return for good farm practice are also now available, and corncrake numbers seem to have started very slowly improving on the islands.

Other birds present in healthy numbers on the machair, while becoming rarer on the mainland, include corn bunting and twite. The lack of pesticides used on the crops means that there are plenty of beetles and caterpillars that birds can catch to feed their young. Also, after the harvest, the abundant fields of stubble and seeds from wild flowers ensure there is enough food for the birds to survive the winter as they rove the machair in their large flocks.

Of all the birds on the machair, the habitat is most famous for its breeding waders, with an estimated 17,000 pairs on the western fringes of the Uists and Barra alone. The most numerous breeding wader is the lapwing, but there are also large numbers of dunlin, ringed plover, oystercatcher, redshank and snipe. Because of the rich mosaic of habitats, the rotational form of agriculture and the lack of ground-based predators on the islands, these machair locations may well hold close to 40 per cent of the entire British breeding population of dunlin and close to a third of lapwing and ringed plover.

Curiously, the only recent threat to the waders has been the introduction of the hedgehog, as Miss Tiggywinkle has an unfortunate penchant for wader eggs. With efforts being made to tackle this problem, however, there is hope that the display calls of the lapwings, snipe and corncrake, in addition to the vast wild flower blooms, will be spectacles for many years to come in the land of the machair.