Kitabı oku: «The Isles of Scilly»
Collins New Naturalist Library
103
The Isles of Scilly
Rosemary Parslow
Editors
SARAH A. CORBET, ScD
PROF. RICHARD WEST, ScD, FRS, FGS
DAVID STREETER, MBE, FIBIOL
JIM FLEGG, OBE, FIHORT
PROF. JONATHAN SILVERTOWN
The aim of this series is to interest the general reader in the wildlife of Britain by recapturing the enquiring spirit of the old naturalists. The editors believe that the natural pride of the British public in the native flora and fauna, to which must be added concern for their conservation, is best fostered by maintaining a high standard of accuracy combined with clarity of exposition in presenting the results of modern scientific research.
Table of Contents
Cover Page
Title Page
Editors
Map
Editors’ Preface
Author’s Foreword and Acknowledgements
CHAPTER 1 An Introduction
CHAPTER 2 Geology and Early History
CHAPTER 3 Later History - People and Their Influence on the Islands
CHAPTER 4 Naturalists and Natural History
CHAPTER 5 St Mary’s
CHAPTER 6 The Off-Islands
CHAPTER 7 The Uninhabited Islands
CHAPTER 8 The Sea and the Marine Environment
CHAPTER 9 The Coast
CHAPTER 10 Grassland and Heathland
CHAPTER 11 Woodland and Wetland
CHAPTER 12 Cultivated Habitats - Bulb Fields and Arable Plants
CHAPTER 13 Gardens
CHAPTER 14 Insects and Other Terrestrial Invertebrates
CHAPTER 15 Mammals, Reptiles and Amphibians
CHAPTER 16 Birds
CHAPTER 17 The Future
APPENDIX Vegetation Communities
References and Further Reading
Species Index
General Index
The New Naturalist Library
About the Author
Copyright
About the Publisher
Map
Editors’ Preface
EARLIER VOLUMES OF the New Naturalist library have concerned the natural history of the islands of northern Britain – the Highlands and Islands (1964), Shetland (1980), Orkney (1985) and the Hebrides (1990). Here, in the Isles of Scilly, a group of islands at the extreme southwest of Britain presents a totally different aspect of island natural history.
Any account of the natural history of the Isles of Scilly has to comprehend an unusually wide variety of life and environments. In this striking archipelago of inhabited and uninhabited islands, southwest of Land’s End and on the fringes of the Atlantic, marine and terrestrial natural history are intimately connected. The oceanic climate, with mild summers and winters and stormy weather, exerts a strong influence, resulting in a flora and fauna unique in Britain. Added to this is the effect of thousands of years of human occupation, governed by changing economic conditions and isolation from the mainland, a history which has produced, for example, an extraordinary mix of native, introduced and cultivated plants.
The author, Rosemary Parslow, has an unrivalled knowledge of the natural history of the Isles of Scilly, gained over nearly fifty years of active involvement in observation and survey. Her studies have included the marine life and the life of terrestrial environments, including both fauna and flora. With such a range of practical experience, she is in an excellent position to give a synthesis which covers the variety of natural history of the islands, as well as issues of conservation and future development. Such a synthesis will be welcomed by Scillonians and by the many visitors to the islands, as well as by those with wider interests in the British fauna and flora.
Author’s Foreword and Acknowledgements
HOWEVER OFTEN YOU go to Scilly it is still a magical experience as the islands slowly emerge out of the line of clouds on the horizon, to resolve into a mass of shapes and colours against the sea and sky. Whether you go there by boat, stealing up gradually on the islands, or by air, flying in low over the coastline of St Mary’s to land with a rush on the small airfield – like one of the plovers that feed there on the short turf – it brings a thrill of excitement every time.
I first went to Scilly in 1958, to stay at the St Agnes Bird Observatory that had started up the previous year. It was an ‘un-manned’ observatory, run by a committee of enthusiastics, organising self-catering holidays for groups of bird-ringers to operate it as a ringing station over the spring and autumn migrations. The first year had been based in tents at Lower Town Farm, but by the time of my visit they were renting the empty farmhouse. Like many similar establishments they ran on a small budget and lots of commitment; the living conditions were very basic, but the surroundings idyllic. That first visit was the start of a lifetime love affair with Scilly, which has influenced my whole adult life and has led to writing this account of the natural history of the islands.
Those early visits were made when I was working as a very junior scientific assistant at the British Museum (Natural History) in South Kensington. At that time collecting specimens was still an important element of the work, in order to build up the Museum’s taxonomic collections. So staff holidays often became unpaid collecting trips, and mine were frequently timed to go to Scilly at the best times for ‘shore collecting’, to collect marine invertebrates. These were when the equinoctial spring tides occur, around Easter and again in autumn, when the most extensive areas of shore are exposed. This was in the days before cheap wet suits and underwater photography meant that marine biologists were no longer constrained by tides. At that time it was boulder-turning and wading and following the tide down to the lowest level accessible, laden with heavy collecting gear. Most of the collecting I did was to order: specific groups of animals were targeted because these were ones where information on their distribution and status was needed, as well as adding representative specimens to the Museum collections. This resulted in a series of Isles of Scilly collections in the 1960s and ’70s, mostly shore fishes, sponges, worms, and other invertebrates, especially echinoderms, my specialist group.
Even after I had left the Museum, a colleague would send a small milk churn packed with collecting paraphernalia to the island of St Agnes to await my arrival for the family holiday, and then we would return it with the carefully preserved and labelled specimens packed inside. This system usually worked very well, but in the early days there were some hiccups – like the time the churn was nearly dispatched to Sicily due to a misunderstanding with the carriers, or the year it was put back on the launch by a puzzled islander because he did not know anyone who used milk churns on the island!
This first-hand experience – firstly the shore collecting, then the species records when collecting specimens became unfashionable, my involvement with the bird observatory, and then starting listing plants – was fortuitous in that it gave me a unique opportunity to study, photograph and get to appreciate the wildlife, scenery and history of these enchanting islands. I have been fortunate in that I was also to spend many weeks over the succeeding years on Scilly, usually based on St Agnes, and later St Mary’s.
Since those early days I have visited the islands at least once every year (except for a break of a couple of years in the late 1960s), have had several prolonged stays, and have been there in every month of the year and probably most kinds of weather. This has probably been the best way of getting to know as much as possible about the islands without being resident there. At various times I have been employed to survey and produce reports on a number of subjects from bats to plants. In 2002 I was commissioned to write a Management Plan for the land leased by the Isles of Scilly Wildlife Trust. This gave me a further opportunity to spend a longer time on the islands, getting to know them, their habitats and the people whose job it is to manage those habitats (Parslow, 2002).
Due to the climate and the geographical position of the islands there are some species, particularly plants, which are not usually easy for the holiday visitor to see. Certainly if you want to see some of the plants which flower in the middle of winter, such as some of the introduced aliens, German ivy Delairea odorata and some of the Aeoniums, then a visit at Christmas or New Year is essential. This is also a good time to find the tiny least adder’s-tongue fern Ophioglossum lusitanicum, a great rarity found in Britain only on the Channel Isles and on St Agnes in Scilly. Every month has its specialities, so there is always something to look out for at any time of the year. If your interests are more ornithological then everyone will recommend the spring and autumn migrations for the ‘falls’ of unusual migrants. In summer there are breeding seabirds, and a boat trip can take you out to see puffins, shags, guillemots, fulmars and other seabirds among the uninhabited islands – and there are also grey seals hauled out among the distant rocks. Even in winter there are peregrine and raven to look out for, and sometimes in cold weather large numbers of woodcock seem to fall out of the sky. For the other natural history groups, lichens, insects, fish or seaweeds, there are nearly always things to do and things to see!
It is not possible to write about the flora and fauna of the Isles of Scilly without considering all the other aspects that go to make them so unique. Their geography, geology and climate are intimately bound up with the history of the people of the islands, the way they have used the land, and present-day management. Over the next few chapters we will consider many of these aspects of the islands, as well as the major habitats found in Scilly – the heathlands, coastland, cultivated fields and wetlands. Each of the islands has its own unique character and special plants and animals – from St Mary’s and the inhabited smaller ‘off-islands’ to those uninhabited islands and rocks which are home to the rest of the islands’ wildlife. Then there are those people who have been important in the study of the island flora and fauna, the story of the rise in popularity of the islands for birdwatchers, the effect climate has had in shaping the flora and the escapes from cultivation which have now become established as part of the landscape. The sum of all these is what makes up the fabric of these unique and beautiful islands, the Isles of Scilly.
ACKNOWLEDGEMENTS
Compiling this book has taken a long time; it represents several decades of involvement with the Isles of Scilly, and it would never have been written without the help and encouragement of many people. There are too many individuals to mention everyone, but I hope that they will understand that I am hugely grateful to them all. The real generosity of those naturalists who allowed me free access to their work and who commented on sections of the text has made it possible for me to include many aspects of flora and fauna about which I know very little.
The artwork in this book has been selected from a huge volume of material I have been offered; unfortunately I could only use a small selection. Many of the photographers and artists also helped in other ways, with information and comments. For permission to use their material I would like to acknowledge Andrew Cooper, Paul Gainey, Sandra Gibson & Frank Gibson (Gibson Collection), Martin Goodey, Richard Green, Mark Groves, Alma Hathway, Ren Hathway, David Holyoak, Chris Hopkin, David Mawer, Paul Sterry, Bryan Thomas, Ian Wallace, the Isles of Scilly Museum (for Hilda Quick woodcuts) and the Cornwall Archaeological Unit and Jeanette Ratcliffe. I consulted libraries at the Cornish Studies Library, Redruth, the Natural History Museum, London, and English Nature (now Natural England), Truro.
I am very grateful to the many people in the Isles of Scilly who have helped in so many ways, although space does not allow me to mention them all. In particular I thank Martin Goodey, Anne and Mike Gurr, Ren Hathway and Jo Wrigley, Wendy Hick, Francis and Carol Hicks, Johann Hicks, Lesley and David Knight, Jim Liddon, Julie Love, Amanda Martin (IOS Museum), Cyril Nicholas, Steve and Julia Ottery (and the Museum Flower Ladies), Adrian and Mandy Pearce, Penny Rodgers.
Specific help and comments on individual chapters and topics were generously given by Jon Akeroyd, J. F. Archibald, Ian Bennallick, Sarnia Butcher, Adrian Colston, Bryan Edwards, Bob Emmett, Chris Haes, Steve Hopkin, Julia MacKenzie, Rosalind Murphy, John Ounstead, Helen Parslow, John Parslow, Mark Phillips, Peter Robinson, Katherine Sawyer, Sylva Swaby, Andrew Tompsett, Stella Turk, Steve Westcott and Will Wagstaff Keith Hyatt not only read all the first draft text but found lots of useful snippets of information as only he can; Ian Beavis freely allowed use of all his material on Aculeate Hymenoptera and other groups; Jeremy Clitherow and Alison Forrester (English Nature) gave me access to many unpublished reports and other scientific information; David Mawer (IOSWT) has been a constant source of information on all aspects of natural history in the islands. The Isles of Scilly Bird & Natural History Review published by the ISBG has also been a rich source of recent information.
I must also acknowledge the team at HarperCollins, especially Richard West, who read the first draft, Helen Brocklehurst and Julia Koppitz, and above all Hugh Brazier, for many improvements to the text.
To my son Jonathan (Martin) Parslow and daughters Annette and Helen, who shared the early visits to Scilly and still love Scilly as much as I do, I dedicate this book.
CHAPTER 1 An Introduction
It’s a warm wind, the west wind, full of birds’ cries; I never hear the west wind but tears are in my eyes.
For it comes from the west lands, the old brown hills, And April’s in the west wind, and daffodils.
John Masefield, The West Wind
ALTHOUGH MASEFIELD probably did not have the Isles of Scilly in mind when he wrote those lines, they often remind me of the islands. In the early days of the year the low hills are brown with dead bracken stems and heather and there are daffodils and narcissus everywhere (Fig. 1). Seabirds wheel and call and often the climate is quite mild and balmy.
The rocks and islands that form the Isles of Scilly are located about 45 kilometres (28 miles) southwest of Land’s End. Mysterious, romantic and beautiful, they have long exercised the imagination of storytellers and historians, and legends abound that the Isles were once the lost islands of Lyonnesse or the undersea land of Atlantis. Or they may have been the islands known to the Greeks and Romans as the Cassiterides, the Tin islands, although there is little evidence of there having ever been any significant tin-mining on the islands.
The hills in Scilly are not high: most are under 45 metres, and the highest point is near Telegraph on St Mary’s, 49 metres above chart datum. The Isles of Scilly archipelago forms a roughly oval-shaped ring of islands in shallow seas of fewer than 13 metres in depth, except for the deep channels of St Mary’s Sound between St Agnes and St Mary’s, Smith Sound between St Agnes and Annet, and the deep waters towards the Western Rocks. Among the main group of islands are extensive sand flats the sea barely covers, with less than three
FIG 1. February on St Agnes, with daffodils flowering among the dead bracken. (Rosemary Parslow)
metres depth of water over much of the area at high tide, and with wide sand spits and shallows. At low water St Martin’s may be inaccessible by launch.
When you fly into the islands you first see the low-lying islands of the Eastern Isles looking green and brown with vegetated patches and rock (Fig. 2). Often the sand spits in the turquoise sea over the sand flats are revealed before you descend over the neat fields and cultivated land of St Mary’s to land on the airfield (Fig. 3). From the air the huge number of tiny islands and the many reefs and rocks under the water show how easily so many hundreds of ships have been wrecked in Scilly over the centuries (over 621 known wrecks have been recorded) (Larn & Larn, 1995). Even today, with depth gauges, GPS and radar, as well as more accurate charts, ships and other craft still get into trouble among the islands every year.
The inscription on an eighteenth-century map based on Captain Greenville Collins’ Great Britain’s Coasting Pilot survey (Fig. 4) refers to one of the most notorious Scilly shipwrecks, in addition to several other features of the islands:
The Ifands of Scilly are very fruitfull abounding in Corn & Pasture, here are plenty of Conies, Crains, Swans, Herons, Ducks, & other Wild Fowl, thefe Islands were Conquer’d by Athelstana Saxon King, & have ever since been Counted part of
FIG 2. The Eastern Isles: the view from Great Arthur towards Little Ganilly and St Martin’s. (Rosemary Parslow)
FIG 3. A patchwork of bulb fields, St Mary’s, February 2004. (Rosemary Parslow)
FIG 4. Eighteenth-century map of the Isles of Scilly, probably based on the Great Britain’s Coasting Pilot survey by Captain Greenville Collins, first published in 1693.
Cornwall: they are about 60 miles from the Lands End in Cornwall & are reckoned to be 145 in number; one of them called Scilly which gave name to the rest was counted ye chief, but St Mary’s has now got the preeminence; they are dangerous to be approach’d by strangers on account of the hidden Rocks & have been fatal to many Ships of our own Nation, & particularly to Sr. Cloudsley Shovel with 3 other Men of War who where all lost here on the 22. of Oct. 1707 at night, on their return home from the Siege of Toulon. There is however a safe passage from these Islands, where Ships are furnish’d with Pilots from the Place; and there are secure Harbours in them large enough to receive the Royal Navy: & particularly at St Mary’s, where there is a commodious Harbour & a Castle built by Queen Elizabeth.
Although there is an island called Scilly Rock off the west coast of Bryher that is reputed to have given its name to the group, this is probably not so. In the Middle Ages the name for all the islands was variously Sullia or Sullya, becoming Silli later. The current spelling as ‘Scilly’ is a more recent form to prevent confusion with the word ‘silly’ (Thomas, 1985). The islands are usually referred to as the Isles of Scilly or Scilly, never the Scilly Isles!
There are five islands that are now inhabited, plus some forty or so uninhabited (by people, that is – rather arrogantly we ignore the other inhabitants) and large enough to have vegetation on them, and then a further 150 or so rocks and islets. The figure cannot be definite as every stage of the tide changes one’s perspective as land is alternately exposed and hidden by the sea. From the isolated Bishop Rock with its tall lighthouse in the southwest of the group (Fig. 5) to Hanjague, east of the Eastern Isles, is 17.5 kilometres, and the archipelago
FIG 5. The Western Rocks and the Bishop Rock, the westernmost point of the Isles of Scilly, with resident grey seals. (David Mawer)
extends some 13km from north to south. The islands have a total land area of about 1,641 hectares or 16km2, more of course at low tide when more land is uncovered (Table 1). Situated on latitude 49° 56’ N and longitude 6° 18’ W, the islands are on the same latitude as Newfoundland, but the climate under the warming influence of the Gulf Stream is very different. Although the islands are part of Watsonian vice-county 1 (West Cornwall) for recording purposes, they are often treated as vice-county 1b for convenience. All the islands fall within four 10km grid squares, with most of the land being contained within just three, the fourth square being mostly water.
TABLE 1. The Isles of Scilly: areas of the principal islands. Areas are all in hectares at MHWS. (Figures from Isles of Scilly Wildlife Trust)
Isles of Scilly total area at MHWS = 1,641ha
Total area at LAT (lowest astronomical tide) = 3,065ha
Number of islands (includes rocks and stacks) of any size at MHWS = 818
Number of islands at MLWS = 3,825
Number > 0.03 ha at MHWS = 203
Number > 0.09ha (so possibly with some vegetation) = 101
CLIMATE
The climate of the Isles of Scilly is characterised as oceanic, with mild wet winters, mild sunny summers, frequent strong winds and gales, and also sea fogs. A major influence on the climate is the North Atlantic Drift, an arm of the Gulf Stream. Compared with the Cornish mainland Scilly has milder winters (February mean 7.3°C) and cooler summers. The average monthly mean temperature is 11.7°C (National Meteorological Library). With most days in the year having a temperature usually above 5°C, many plants can grow in Scilly that cannot survive on the mainland. This also includes winter annuals that grow throughout winter and flower very early in spring. As many plants on the islands are frost-sensitive the occasional bad winter can cause a considerable amount of damage. Fortunately snow and frost are much less frequent than on the adjacent mainland. Snowfalls are relatively infrequent; frosts are occasional and usually neither very hard nor long-lasting.
The rare occasions when there have been more severe frosts have had a devastating effect on the vegetation, especially the ‘exotic’ plants. Winter 1987/8 was one such occasion, with almost all the evergreen Pittosporum hedges being either killed outright or cut to the ground. Hottentot fig Carpobrotus edulis is one species that can be susceptible to both frost and salt water, but as the stands are usually dense there is nearly always a piece of the plant protected enough to survive and grow again. Rainfall is low compared with Cornwall, 825mm per year on average; some of the rain clouds appear to pass over the low islands without precipitation. The islands are prone to sea fogs and this increases the general humidity, which is reflected in the rich lichen flora – also an indicator of the clean air and lack of industrial pollutants.
As the former Duchy Land Steward wrote, ‘the weather in Scilly is characteristically unpredictable’ (Pontin, 1999). Gales and strong winds over force 8 are a frequent feature, and not just in winter: gales can happen throughout the year. Visitors can sometimes find themselves marooned on the island they are staying on for several days when the boats stop plying due to rough seas. Some of us have considered this a bonus at times!
THE SCILLONIANS
The Isles of Scilly have had almost 4,000 years of continuous occupation since the arrival of Bronze Age farmers (Thomas, 1985), but for centuries before that nomadic people who left little sign of their presence other than a few flints had visited the islands. The population has fluctuated and there have been many incomers over the centuries. Not many of the current families can trace their ancestors back more than a few hundred years, usually to the 1640s or 1650s (court records show the Trezise family was in the islands in the thirteenth century). Some are probably descendants of soldiers who came to man the Garrison and married local women. The inhabitants of St Agnes used to be known as Turks as they tended to be short and swarthy and were reputed to have had an exotic ancestry. As on other British islands such as Orkney (Berry, 1985) there has been a continuous stream of people, including Neolithic visitors, Bronze Age and Iron Age inhabitants, pirates, smugglers, Cromwellian soldiers, Royalists, French traders, British servicemen in both World Wars, land-girls, and men and women who came to staff hotels and other establishments. Many of these peoples stayed, married locals, and their descendants have added to the rich mix of heritage in the population.
Population
The resident population of the islands has stayed at around 2,000 for many years. Of these about 1,600 live on St Mary’s, with about 160 on Tresco and 100 on each of the other inhabited islands (St Martin’s, Bryher and St Agnes). During the summer holiday season visitors approximately double the population.
The Duchy of Cornwall
The Isles of Scilly became part of the original Duchy of Cornwall in 1337 when Edward, the Black Prince, became the first Duke of Cornwall. Today the islands are still owned by the Duchy, administered by a resident Land Steward. The Duchy is governed by a Council, of which His Royal Highness the Prince of Wales and Duke of Cornwall is Chairman. Much of the land on the inhabited islands is in agricultural tenancies, with the exception of the island of Tresco, which is leased to the Dorrien-Smith family, and Hugh Town, which became freehold in 1949 (Mumford, 1987). In 1999 there were some sixty farm-holdings, covering 557 hectares, of which 182 are in horticultural use, mostly bulbs. The average farm on the smaller islands of Bryher, St Agnes and St Martin’s is very small, sometimes less than 10 ha, although those on St Mary’s and Tresco are proportionately larger. Many fields are equally small, some less than 0.1ha (Pontin, 1999). Some 1,845 hectares of the unfarmed land are now leased to the Isles of Scilly Wildlife Trust, mostly heath, wetland and coast on the inhabited islands and including all the uninhabited rocks and islands.
The Council of the Isles of Scilly
The Council of the Isles of Scilly is a unitary authority (Local Government Act 1972, as applied by the Isles of Scilly Order 1978). This means the Council has unusual powers in that it has all the functions of county, district and parish councils as well as replacing the Environment Agency and the airport authorities in the islands. The islands are not automatically included in all national legislation. There are sometimes specific references or amendments to ensure that legislation also refers to the islands.
TRAVELLING TO THE ISLES OF SCILLY
These days getting to Scilly is no longer the difficult and chancy business it was in the past, and we can easily forget that for earlier visitors the journey was frequently an ordeal. Passengers could arrange to go by sailing ship to the islands, but it was not until the start of the regular mail boat after 1827 that there was an organised service from Penzance to St Mary’s. Even so the passage usually took eight to nine hours and at times as much as two days. Things picked up when a steamer service started about 1858, and a year later the railway was extended to Penzance. Then in 1937 the air service started linking Scilly with the mainland, offering an alternative and much quicker route for those reluctant to brave the sea crossing.
The RMV Scillonian (Fig. 6) is the third of that name to have carried freight and passengers between Scilly and the Cornish mainland. She sails most days (except Sunday) between spring and autumn, the crossing taking about two and a half hours according to conditions. The Scillonian is notorious for her rolling motion, which is due to her shallow draft, designed to enable her to enter the shallow waters around the islands; but the possibility of seeing unusual seabirds, cetaceans and other excitements during the passage makes her popular with many visitors. The alternative routes to Scilly are by air, either fixed-wing plane or helicopter, both of which take about twenty minutes; but neither flies if there is fog. Flying is the only route in winter when the Scillonian is laid up. A second ship, the MV Gry Maritha, now transports most freight to the islands. Inter-island launches meet the ships in St Mary’s and transfer goods of all kinds to the ‘off-islands’, as the other four inhabited islands are known locally.
FIG 6. The RMV Scillonian in harbour after her two-and-a-half-hour sail from Penzance. July 2006. (Rosemary Parslow)
Tourism
It was not until after World War II that Scilly became really popular as a holiday destination, with hotels and guesthouses opening up to accommodate many more visitors, including many naturalists. In 2003 Scilly attracted 122,000 visitors (Isles of Scilly Tourist Information). Tourism now accounts for some 85 per cent of the island economy, although apparently a significant amount of the profits goes off the islands to the mainland-based owners of holiday property and hotels. Most visitors stay in holiday accommodation on the islands, including hotels, guesthouses, cottages and camp sites. Others arrive and stay on their yachts and motor cruisers.
THE UNIQUENESS OF THE SCILLONIAN FAUNA AND FLORA
We will see in later chapters that the Isles of Scilly aptly demonstrate the phenomenon of island biogeography. In all groups of flora and fauna there is a paucity of species compared with Cornwall, and this is a theme to which we will return. This paucity is readily attributed to the distance from the mainland, the much smaller land area and the limited range of habitats compared with those in Cornwall, with no rivers, only a few tiny streams, no acidic mires (bogs) and only granitic bedrock, with none of the slates, serpentinite and other rock types of the mainland. Widespread exposure of habitats on the Isles of Scilly may also account for the absence of some species that are susceptible to wind-blown salt spray. For example there are currently about 217 bryophyte species (57 liverworts, 3 hornworts, 157 mosses). Of these, six liverworts and five mosses are species introduced in Britain. Compared with Cornwall the total bryophyte flora is much poorer, with only about 36 per cent of the overall Cornish total of 167 liverworts (including hornworts) and 37 per cent of the total of 430 mosses. Scarcity of basic soils on the Isles of Scilly may also account for the absence of some other species common in Cornwall.
The number of species of land birds in Scilly is also small. Visitors to the islands are usually surprised to find many common passerines, let alone owls and woodpeckers, missing or in very low numbers. Equally the very confiding nature of blackbirds Turdus merula and song thrushes T. philomelos will soon be remarked on. The Isles of Scilly have hardly any land mammals, and no predators such as foxes Vulpes vulpes or stoats Mustela erminea. There are no snakes and very few resident species of butterflies or dragonflies; this is common for all groups. But on the other hand there are species that are only found in Scilly, such as the Scilly shrew Crocidura suaveolens cassiteridum, several rare lichens and many other examples of interesting and uncommon species.
Lusitanian and Mediterranean influences
References will be made in the following chapters to Lusitanian influences. The geographical position of the Isles of Scilly has led to a number of unique aspects of the flora and fauna. Many species are at their northern limit in Scilly and southwestern Britain. These are species from the Atlantic coastal regions of southern Europe, based on the former Roman province of Lusitania, and into the Mediterranean. A visit to parts of Spain or Portugal will reveal many species of plants that are commonly seen in Scilly, but that are rare of absent from the rest of Britain. There are also lichens, invertebrates and other groups with Lusitanian species that reflect the same distribution, and in the marine environment many species found in southern or Mediterranean waters that also occur in the Isles of Scilly and the Channel Islands. In the New Atlas of the British and Irish Flora (Preston et al., 2002) the floristic elements of the flora are described: the Mediterranean-Atlantic and Submediterranean-Subatlantic are plants that are associated with these biogeographical regions.
NATURE CONSERVATION DESIGNATIONS
Currently the Isles of Scilly are covered by a plethora of designations relating in some way to nature conservation.
The whole coastline of the Isles of Scilly was designated a Heritage Coast in 1974.
Scilly is a candidate Special Area of Conservation (cSAC) under the European Habitats Directive.
A Special Protection Area (SPA) (for birds) covers 4.09km2.
Scilly is a Ramsar site, an international important-wetland designation.
Scilly was designated a Conservation Area in 1975.
Twenty-six sites have been designated Sites of Special Scientific Interest (SSSI) by English Nature. Of these five are geological sites.
The Isles of Scilly has been a Voluntary Marine Park since 1987 – this includes the whole area within the 50m depth contour line.
Scilly was designated an Area of Outstanding Natural Beauty (AONB) in 1975 – it includes ‘all the islands and islets above mean low water that together form the Isles of Scilly’. The total area covered is 16km2. Scilly is the smallest AONB in the country; also the only one under a single local authority. The Management Plan for the AONB was published in 2004.
STUDYING THE FLORA AND FAUNA OF THE ISLES OF SCILLY
Although many of the visitors to the Isles of Scilly over the centuries have commented on the natural history of the islands, most of what has been written has concentrated on the most obvious groups. Authoritive books have covered plants, birdlife, butterflies and moths, but many of the marine species, insects and more difficult groups are the subject of papers in scientific journals or rather inaccessible unpublished reports held by English Nature and other bodies. Recently there has been a resurgence of interest in these other groups, especially invertebrates and marine life, which had otherwise been left to a small number of specialists.
For many years botanists have been well served by a Flora (Lousley, 1971), but it is now due for an update as there is a great deal of new botanical information available. Some plant hunters whose aim is to record rare plants, and especially alien species, are regular visitors to the islands.
Birds have tended to attract the lion’s share of attention since the late 1950s, when the St Agnes Bird Observatory became a focus for birdwatchers hoping to see rare and unusual migrant and vagrant species. October is still the most popular month for birdwatchers to visit Scilly. This is an extraordinary phenomenon; it has to be seen to be believed. Hundreds of enthusiasts, bristling with telescopes, pagers and binoculars, arrive in Scilly intent on seeing rare migrant birds. These birders mostly have well-defined patterns of behaviour, usually travelling en masse to wherever there is news of some exciting bird. So it is not unusual to see them all gathered in one place, behind lines of telescopes waiting patiently for a glimpse of their quarry. In the evenings many will attend the ‘count’, when the tally of the day’s finds are recorded.
The marine habitat might seem to be rather neglected. Although there are organised field trips to Scilly to study marine ecology, most of the information stays in student dissertations. But for every child visiting the islands half the fun is exploring rock pools. Now, with plenty of opportunities to dive or snorkel, the underwater life is becoming much better known. Underwater safaris, glass-bottomed boats and swimming with seals and seabirds are making this fascinating medium much more accessible to the general public.
Some of these visitors to Scilly are going to take more than a casual interest in what they see. Hopefully they will contribute records and notes that will lead to further expansion of our knowledge of the natural history of the islands. Since its inception the Isles of Scilly Bird Group has produced a report that also includes notes, short papers and reports on natural history subjects other than birds – the Isles of Scilly Bird & Natural History Review. Perhaps this book too will encourage an interest in the fascinating natural history of the Isles of Scilly.
The chapters that follow are arranged to give an overview of the geology, something of the history, the people who contributed to our knowledge of the natural history of the islands, the individual islands, the main habitats, and the major groups of flora and fauna. Descriptions of some of the plant communities are included as an appendix.
CHAPTER 2 Geology and Early History
There are signs of Bronze Age man on every island in Scilly.
Charles Thomas (1985)
GEOLOGY
AT FIRST GLANCE the Ordnance Survey’s geological map of the Isles of Scilly appears to be something of a disappointment: almost the whole of the land shown on the map is coloured in the same shade of red-brown, representing granite. A granite batholith, the Cornubian batholith, extends as a series of cupolas or bosses along the Southwest Peninsula from Dartmoor to Land’s End and the Isles of Scilly, ending at the undersea mass of Haig Fras 95km further on and slightly out of line, presumably due to faulting (Edmonds et al., 1975; Selwood et al., 1998). Originally the rocks were a softer, slatey rock called killas; this was altered by pressure from the granite boss as it was extruded and pushed up into the killas, which was later eroded and now only exists as rock called tourmalised schist, found as a narrow dyke-like patch on the northwest of St Martin’s (Anon., Short Guide to the Geology of the Isles of Scilly).
The Scilly granite is very similar to that found in Cornwall, and was classified by Barrow (1906) into different types, the main ones being the older, coarse-grained G1, which is found mainly around outer the rim of the islands, and G2, which is finer-grained and is mostly in the central part of the islands and has often been intruded into G1. The two types of granite merge into each other without any obvious line of demarcation. Characteristically the granites are made up of quartz and crystals of feldspar, muscovite mica, biotite mica and other
FIG 7. Loaded Camel Rock at Porth Hellick, St Mary’s, May 2006. (Richard Green)
minerals. Much of the rock is beautifully striped through with veins and dykes, mostly narrow and usually white or black according to the infilling; white quartz or black tourmaline crystals can be found in these dykes, and rarely larger crystals of amethyst quartz. A vein of beautiful amethyst quartz that runs through some of the rocks to the north of St Agnes at one time had large, visible crystals, but most have since been taken by collectors. It is still possible to find smaller veins of crystals, and some beach pebbles have small layers of crystals running through them.
Another characteristic of the granite is the weathering along the veins and softer areas in the rock. The cooling and pressures have already formed these into very distinctive vertical and horizontal cracks, and erosion by weather and the sea then combine to produce the most extraordinary natural sculptures. Some of the most impressive examples can be seen on Peninnis Head and along the east coast of St Mary’s, but all the islands have examples. Some of these rocks have been given fanciful names: Pulpit Rock, Monk’s Cowl, Tooth Rock, Loaded Camel (Fig. 7). A curious type of formation seen frequently in Scilly is a rock basin in the top of a granite boulder where rainwater has weakened feldspar and released quartz crystals, which apparently have blown round and round to form a natural bowl.
Surface geology
When the granite weathers it eventually becomes reduced to sand. Blown sand is an important constituent of the soils of all the islands as well as forming the beautiful white beaches and the sand bars that link many of the higher parts of the islands. Ram (also known as head or rab) is a cement-like material formed by the breakdown of periglacially frost-shattered granite fragments that forms deposits around the bases of granite carns, in valleys and especially in the cliffs (Fig. 8). It is often excavated from ‘ram pits’ to be used by the islanders as a mortar in building work and sometimes as a road surface. Alluvium is found under the Porthloo fields, and at Lower and Higher Moors. Small patches of gravel found near the daymark on St Martin’s and at a few other places are probably of glacial origin – see below.
FIG 8. Ram shelf at the base of the cliff on Samson. (Rosemary Parslow)
FIG 9. An example of a raised beach at Porth Killier, St Agnes, where former beach levels can be seen above the present beach. May 2003. (Rosemary Parslow)
Raised beaches
Raised beaches are especially common throughout the southwest of Britain, and the Isles of Scilly have many examples. The raised beach at Watermill is a classic site with a conglomerate of clast-supported rounded cobbles and boulders, overlain by well-sorted medium sand (Selwood et al., 1998). There are many places all around the coasts in Scilly where former shore levels with beach deposits are exposed in the cliffs above the present beaches. There are raised beaches at Hell Bay, Bryher; Porth Killier, St Agnes (Fig. 9); Piper’s Hole, Tresco; Shipman Head, Bryher and many other places.
Glaciation
Although it was long thought that glaciation had missed Scilly, there is evidence that a tongue of ice from the southern edge of the Late Devensian ice sheet, the Irish Sea Ice Stream, probably reached the northern islands of Scilly 18,000 years BP (before present), eventually leaving deposits on White Island off St Martin’s, and on Northwethel (Scourse et al., 1990). The evidence for this lies in a great variety of rocks exotic to Scilly such as flint, sandstone and associated ‘erratics’. The best example of glacial till in the islands is within the Bread and Cheese
FIG 10. The bar to White Island is a former glacial feature, probably a glacial moraine. June 2002. (Rosemary Parslow)
formation at Bread and Cheese Cove SSSI on the north coast of St Martin’s: the overlying gravels, the Tregarthen and the Hell Bay gravels, are interpreted as glaciofluvial and solifluction deposits respectively. There are erratic assemblages with both deposits (Selwood et al., 1998). Recent work suggests that some of these deposits, such as that at Bread and Cheese Cove, may not be in their original positions (Hiemstra et al., 2005). Other sites with glacial links occur in the bars in the north of the islands, such as the ones at Pernagie, the one connecting White Island to St Martin’s (Fig. 10), and Golden Bar, St Helen’s: these are probably glacial moraines, not marine features (Scourse, 2005).
EARLY HISTORY – THE SUBMERGENCE
Twenty thousand years ago most of Britain was under the last glaciation, extending as far south as the Wash and south Wales. At this time sea level would have been as much as 120m below Ordnance Datum. Then the climate ameliorated and by 13,000 BP the Devensian ice had almost disappeared (Selwood et al., 1998).
Four thousand years ago, before the sea inundated the land, Scilly would have had a very different landscape, with low hills and sand dunes surrounding a shallow plain (Fig. 11). Based on the present-day undersea contour lines, there would at that time have been three main islands: the principal one would have included the present-day St Mary’s, Tresco, Bryher and St Martin’s, the Norrard Rocks, the Eastern Isles and the St Helen’s group; Annet and St Agnes would have made up a smaller second island group; and the Western Rocks would have been the third. Later the islands became parted as the sea rose still further. The long isolation of St Agnes from St Mary’s and the rest of Scilly may possibly explain the differences in the flora – for example why the least adder’s-tongue fern Ophioglossum lusitanicum is restricted to St Agnes.
Most accounts of the submergence of the Isles of Scilly are based on the model proposed by Thomas in Exploration of a Drowned Landscape (1985). Thomas suggests that sea level rose rapidly and reached to within a few metres of present-day levels by 6000 BP, although final submergence of the island of Scilly to
FIG 11. A map showing how the main islands may have appeared prior to the submergence. (After Thomas, 1985)
create the present archipelago may not have been effected until post-Roman times. Archaeological and historical evidence show that although sea was rising on a unitary island about 2000 BC, ‘submergence began in earnest during Norman times and was effectively completed by the early Tudor period’ (Thomas, 1985; Selwood et al., 1998). However, Thomas recognised that although his model assumes a gradual process of submergence, there is an alternative picture with a series of dramatic events such as tidal surges. According to Ratcliffe and Straker (1997), submergence may have been even more gradual than Thomas proposes. The most controversial aspect of Thomas’s model is his suggestion that separation of the islands did not occur until early Tudor times. Although the exact details of when and how the marine inundation took place are unclear, remains of huts, walls and graves on areas now covered by the sea are irrefutable evidence that it took place.
THE EARLY LANDSCAPE
During glaciation, land south of the ice sheet would have been bare tundra, cold, with sparse vegetation and probably few animals (Yalden, 1999), and certainly few that are still found in Britain today. It is difficult to imagine what Scilly was like at the time of the earliest human visitors, who were probably Mesolithic hunter-gatherers who left only a few flints as evidence of their passing. We have already seen that the islands would have been a considerably larger landmass than the present-day scatter of islands. Much of the land was covered in birch woodland, sparse grassland and marshy land with sedges. These conditions of the Mesolithic period persisted across southern Britain, then part of Continental Europe, and most of the steppe species that were present then have either died out or retreated to more northerly areas. During the Neolithic period people may have started to settle in Scilly and begun clearing the land, but pollen evidence shows some forest clearance was followed by woodland regeneration and agricultural decline. There are a few artefacts from this time, but it is likely these were only temporary occupations (Ratcliffe & Johns, 2003).
EARLY MAMMALS AND OTHER FAUNA
Very few remains of the early fauna of the islands have been found, but one small rodent, the root or Pallas’s vole Microtus oeconomus (very similar to our field vole M. agrestis) was present, as was the red deer Cervus elaphus, and both were still present in Scilly in the Bronze Age.
Modern Scilly is poor in mammal species, and the written records are sparse. Bones found in the Iron Age sections of the excavations on Nornour included Scilly shrew, wood mouse or long-tailed field mouse Apodemus sylvaticus and root vole. The first two are still extant in Scilly, but the root vole is believed to have become extinct at some later period, no remains having been found after Romano-British times (Turk, 1984; Ratcliffe & Straker, 1996). Root voles are no longer found in Britain although there are isolated (relict) populations still in the Netherlands, Scandinavia and eastern Europe (Mitchell-Jones et al., 1999). In late summer 1978 my daughter and I found a vole mandible and two molars in storm debris on the boulder beach below the Porth Killier Bronze Age midden, along with scraps of bone and shards of coarse pottery. These were sent to the Natural History Museum, where the vole remains were identified as root vole (Gordon Corbet, in litt.). Later, in 1982, I had the opportunity to go to Hungary and was able to visit root vole habitat near Lake Kolon, in Kiskunsági National Park. This is an area of rough grassland and Phragmites swamp, which would seem to be typical habitat of the vole. An interesting note by Mitchell-Jones et al. (1999) is that root voles migrate from wetland to dunes or drier habitats in winter, and even into houses.
Other animal remains that have been found from archaeological sites include seals, various cetaceans, red deer, toad Bufo bufo (an amphibian no longer native in Scilly), as well as numerous fish and bird species and domestic horse, ox and sheep, all from Bronze Age sites. Roe deer Capreolus capreolus, seals, cetaceans and domestic animals have been recorded from Iron Age/Romano-British sites. At coastal sites seals, small cetaceans and fish were clearly an important part of the diet of the human inhabitants. Although not listed among the remains of fish and molluscs that have been recorded, the boulder beaches and rock pools can support several species of easily caught edible fish, for example rocklings, the larger gobies and grey mullet Chelon sp. Today the large freshwater pools on the islands also contain very large eels Anguilla anguilla, and these may also have been present in the past.
Further discussion on the early mammal fauna is included in Chapter 15, and prehistoric and historical records of birds are discussed in Chapter 16.
THE EARLY HABITATS
Of particular interest is Thomas’s (1985) description of the reconstructed palaeoenvironment of the early Scillonian landscape and the mapping of four main types of habitat. Some of the evidence for this he based on the pollen records, which unfortunately were limited to the few peat deposits and archaeological digs, and also on the distribution of some significant plants in Lousley’s Flora (1971). The four habitat types he described were stream-drained marsh, woodland, sand dune and open ground (including heath).
There are still marshlands in Scilly today, although they are nowhere near their former extent. Some of the land now under the sand flats between the islands could have been low-lying and boggy, but all that remains now are small wetlands at Higher Moors, Holy Vale and Lower Moors on St Mary’s, now much contracted in area. Even as recently as the 1960s there were wet fields from near Porthloo Pool and Rose Hill through to Lower Moors with yellow iris Iris pseudacorus, lesser water plantain Baldellia ranunculoides and hemlock water-dropwort Oenanthe crocata. Although these areas are still there they are now much drier and less species-rich. Another similar wetland area is now flooded and forms the Great Pool on Tresco. All the other streams and marshy areas are now lost under the sea, but some can still be traced from the geological record. Between Teän and St Martin’s is the deep channel of Teän Sound, which probably marks the route of a prehistoric stream.
One of the most interesting theories propounded by Thomas is his mapping of the ancient woodland cover on the islands by looking at the distribution of woodland species in Lousley’s Flora. From the pollen samples analysed by Dimbleby (1977) from Innisidgen and by Scaife (1984) from Higher and Lower Moors it would seem that Scilly was once covered in woodland. This woodland consisted of oak Quercus robur and birch Betula spp. with an understorey of hazel Corylus avellana and alder Alnus glutinosa (probably where there were wetter areas). Pollen evidence also included some ash Fraxinus excelsior and traces of yew Taxus baccata, and later hornbeam Carpinus betulus and elm Ulmus sp. Virtually nothing of this woodland is evident today, but support for the pollen evidence and what it tells us about former woodland distribution can be extrapolated from the present-day distribution of plants (known as ancient woodland indicators) that have strong ancient woodland associations, for example wood spurge Euphorbia amygdaloides and wood dock Rumex sanguineus (Kirby, 2004). In his Flora of the Isles of Scilly Lousley (1971) comments on a number of these woodland plants that were growing in non-woodland habitats. These fall in very neatly with the pattern of woodland 2000 years ago, as demonstrated by Thomas (Fig. 12).
Since 1971 additional plant records have reinforced the pattern. So it is possible to visualise the kind of woodland that may have grown on the islands at the time, possibly similar to the present-day Wistman’s Wood on Dartmoor, with stunted, twisted trees, wind-pruned into shape and only able to reach any reasonable height where they are sheltered in the hollows between the hills – as happens with the elms in Holy Vale today. The ground cover may have been open, with many of the species that still exist in Scilly. The trees and exposed rocks would also have supported luxuriant ferns and bryophytes. Other evidence of the ancient woodlands that existed on Scilly are the numbers of buried tree trunks that have been found on Tresco in the past, and the few oak Quercus sp. trees and woodland plants in the area still known as Tresco Wood. There are also records of submerged tree trunks on St Mary’s and, more reliably, St Martin’s.
FIG 12. The present distribution of AWI (ancient woodland indicator) plants may indicate where woodland existed before the submergence. (Updated since Thomas, 1985)
The work carried out between 1989 and 1993 by the Cornwall Archaeological Unit (Ratcliffe & Straker, 1996) on a number of cliff-face and intertidal deposits also provided exciting additional evidence for the deciduous Mesolithic/Neolithic forests. In addition, the CAU found further evidence that these forests were being replaced by heathland, grassland and cultivated plants by the Late Iron Age, as people began to have an impact on the land.
The other main habitats, sand dunes and heathlands, are still present. Many of the dunes have been flattened and have become vegetated with grassland and scrub, or are now cultivated fields. Heathlands and grasslands have resulted from the management of the open habitats over centuries. The land would have been utilised in many ways, from grazing for animals to the stripping of turf from the heath to use as fuel – once the inhabitants had cleared most of the woodland.
Pollen analysis
Pollen analysis of samples from Higher and Lower Moors (Scaife, 1984) shows the distribution of pollen and spores in four levels of the peat below the two mires on St Mary’s. Later work investigated more areas of peat (strictly not really peat but humic silts) at Porth Mellon, St Mary’s, and Par Beach, St Martin’s (Ratcliffe & Straker, 1996). The earliest levels are mostly tree and shrub pollens, oak, birch, hazel, some ash, elm and willow Salix sp., also some grass species, sedges, bracken Pteridium aquilinum, other ferns and some aquatic plants. These all point to a landscape with woodland, mire and open-water habitats. The record for Lower Moors has less tree pollen and may fit the theory that the ancient woodland was distributed mainly on the north and east of the island (Thomas, 1985). Pollen samples also show there was some further clearance of the secondary woodland that regenerated after the earlier clearances. This coincided with the more open landscape and evidence of arable, heathland, mire and coastal habitats associated with the Iron Age and Romano-British communities then inhabiting the islands. John Evans (1984), excavating an Iron Age field system at Bar Point, found the kind of plant remains that would be expected to follow after most of the woodland had been cleared. These charred fragments were mostly plants of heathland or acid grassland: grasses, ribwort plantain Plantago lanceolata, vetch Vicia sp., Galium, Medicago, broom Cytisus scoparius, elder Sambucus nigra, gorse Ulex sp., false oatgrass Arrhenatherum elatius, as well as oak.
EARLY AGRICULTURE
It was not until about 2000 BC that the first settlements may have started on Scilly (Ashbee, 1974; Thomas, 1985). The evidence from pollen deposits, and from sources such as middens and other archaeological deposits, shows changes in the palaeoenvironment after the clearing of the forest, resulting in more open landscapes with grass and heathland species (Ratcliffe & Straker, 1996). These clearances coincided with the early settlement of Scilly, when it is presumed the woodland was cleared for timber and firewood, as well as to open up areas for cultivation. The growing of cereals (and possibly other plants that produce edible seeds) and the use of the plough must have happened quite early after the arrival of the first settlers. The excavation of the Iron Age site at Bar Point graphically illustrates the agricultural practice at that time (Evans, 1984), with evidence of stone banks to produce individual fields – not apparently for keeping stock in, but to demarcate ownerships. Cultivation marks left by the rip-ard (a primitive plough) and mattock as well as burnt charcoal from gorse were found, and also hoof prints of domestic animals – horses, cattle, and sheep or goats. Pollen analysis indicated open land without trees or shrubs (although a small amount of oak, alder and hazel pollen was found in one location), and the presence of cereal pollen points to cereal cultivation. Ribwort plantain was ‘in consistent but low abundance’, which suggests cultivation and grazed land. The evidence for deforestation is based on the association of ribwort plantain with pasture and cultivation and its intolerance of competition with woody plants (Godwin, 1975).
Once the islands had been successfully settled one presumes a period of stability and expansion of the human population followed. This is when the great changes in the landscape, the vegetation and animal life in Scilly would have really begun. As the woodland was cleared, perhaps leaving only small areas, more and more land would have been broken up and cultivated to meet the demands of the increasing human population. Farm stock would have been grazed on the open land, cliffs, dune grasslands, coastlands or around the marshy areas. Bell heather Erica cinerea, ling Calluna vulgaris, reed Phragmites australis and bracken would have been cut for bedding and thatching. Beaches would have been scoured to search for edible seaweed, molluscs and fish. Widespread cultivation and grazing became prominent during the second millennium BC, with many evidences of farming in the pollen and charcoal plant remains, querns for grinding grain, bones of farm animals and so on
FIG 13. The remains of an Iron Age and Romano-British settlement are still visible on Halangy Down, St Mary’s. March 2006. (Rosemary Parslow)
(S. Butcher, in litt.). Also the field walls, settlements and lynchets across some fields indicate the impact on the landscape. Cultivation of the islands must have continued over many centuries, as is demonstrated near the Romano-British settlement at Halangy Down (Fig. 13), where Charles Thomas and Peter Fowler found traces of earlier fields with ones on a different alignment underneath.
There are numerous field walls that are now only seen at low water spring tides in the sea off Samson, Teän and some other islands (Fig. 14). These all point to there having been much more land available for grazing or cultivation before it was lost to the sea with sea-level rise. Their presence also suggests that not all the low-lying land was marsh; but only reasonably accessible land would have been divided into fields.
FIG 14. At low tide the lines of ancient field walls are visible in the sand flats off Samson. June 2002. (Rosemary Parslow)
Arable cultivation
Early cereal crops on Scilly included six-rowed (and possibly two-rowed) barley Hordeum vulgare in both the hulled and naked varieties, which have been identified from several archaeological sites. Other crops that have been recorded are emmer wheat Triticum dicoccum, Celtic bean Vicia faba var. minor and oats Avena sp. The origins of domestication have been identified in the area of the Near East some 9,000-10,000 years ago, and barley and other crop species must have gradually made their way to Europe with the early inhabitants and through trade (Smith, 1995).
There is evidence of arable cultivation in the Isles of Scilly at least as far back as the Bronze Age. On Samson archaeologists found a cache that consisted of a cleaned crop of naked barley, probably six-rowed barley, confirming this was grown in the Early Bronze Age. Six-rowed barley (and possibly also two-rowed barley) was clearly an important crop in Bronze and Iron Age Scilly both in the hulled and naked forms – although most of what has been found is the naked variety. Hulled barley has been found at Middle and Late Bronze Age sites. Barley has also been identified from post-medieval deposits at Steval Point, St Mary’s. Emmer wheat and Celtic bean were found with both kinds of barley at sites at Porth Cressa, St Mary’s, and Porth Killier, St Agnes. At Halangy Down, besides the older lynchets beneath those of the Romano-British settlement, a pot was found nearby with impressions of grain in the clay. One intriguing find was of a large number of seeds in the post-occupation layers of a hut at West Porth: these were dated to Late Bronze Age/Early Iron Age and are of great interest as they were of common arable weeds (Ratcliffe & Straker, 1996). Unfortunately there are very few records or remains of plants to give more than a hint of the wild flora of arable fields.
Arable weeds identified from Bronze Age sites in Scilly include vetches, knotgrass Polygonum sp., chickweed Stellaria sp., black bindweed Fallopia convulvulus, small nettle Urtica urens, corn spurrey Spergula arvensis and red goosefoot Chenopodium rubrum. A curious occurrence was ploughman’s spikenard Inula conyza, a plant more usually growing on calcareous soils. It is possible that some plant seeds (for example corn spurrey and knotgrass) were eaten in a kind of porridge. Certainly weed seeds continued to be found from archaeological sites after the Bronze Age, as did emmer and barley. Unfortunately there is not a great deal of evidence of Iron Age cultivation. Only two sites are recorded, Shipman Head, Bryher, and Halangy Porth, St Mary’s (Ratcliffe & Straker, 1996).
There is little information on arable plants from the Late Roman and Early Medieval periods, although there are unspecific barley and oat records from the seventh/eighth-century layer and wheat and barley from the tenth to thirteenth centuries. Weed seeds, most of which could be arable weeds, were also recorded. Some of the plants that are still found in Scilly are believed to have been early introductions as contaminants of seeds or goods brought in from the Continent, even from as far away as the Mediterranean.
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