Extinctions and Invasions

A Social History of British Fauna

Terry O'Connor, Naomi Jane Sykes, Naomi Jane Sykes

• Publisher: Windgather Press
• Year: 2010
• eBook ISBN: 9781905119776
• Topic: Social Sciences
• Subtopic: Archaeology
• Index: Social Sciences

Eight thousand years ago, when the sea cut Britain off from the rest of the Continent, the island's fauna was very different: most of the animals familiar to us today were not present, whilst others, now extinct, were abundant. Over the course of millennia humans have manipulated Britain's fauna. For reasons of fear, suspicion, desire, or simply inadvertently, certain species were brought to extinction. In their place new animals were introduced: some transported purposefully by invading populations, others sent as royal gifts from far off lands, whilst several species arrived as stowaways. The story of each is fascinating, telling of the changing and multi-layered relationship between humans and animals. Drawing on new research in the fields of archaeology, ecology and history, this book examines how human society, culture, diet, lifestyles and even whole landscapes were fundamentally shaped by the animal extinctions and introductions that occurred in Britain since the last Ice Age. In its 22 chapters a wide range of mammal, bird, fish, snail and insect species are considered. All of the chapters include new and original research presented by authors who are acknowledged experts on their specific topic. Extinctions and Invasions advances our understanding of Britain's natural history whilst dispelling the myths that have become established in both popular and academic literature. It is written in a style accessible to the general reader, whilst providing the depth of research needed by academic researchers. Extinctions and Invasions provides a valuable single source of information for archaeologists, natural historians and conservation biologists, as well as interested laypeople.

CHAPTER 1

Introduction – The British Fauna in a Changing World

Terry O’Connor

The post-glacial archaeology of Britain is largely conserved and understood as great monuments and evocative artefacts, or as ‘ancient landscapes’ in which both forms of relic are preserved in abundance. This focus on the man-made is reflected in UK legislation, which gives protection to specific places as Scheduled Ancient Monuments, as Listed Buildings or Archaeological Areas, and which legislates on the ownership of portable antiquities and ‘treasure trove’, itself a fine linguistic and legal relic. There is another, more widespread and familiar, form of archaeological heritage, namely the landscape itself in which we live, in particular the living communities that share that landscape and that interact daily with human lives. Because other branches of legislation deal with the conservation and management of living organisms in terms of present-day concerns over protecting the vulnerable and managing the problematically-abundant, it is easy to forget that the wildlife around us also has a time-depth. It is as much a reflection of past human activity and decision-making as is Stonehenge or Fountains Abbey. The prehistory and history of the British fauna reflects people and other animals adapting to some environmental changes, causing others by accident or design, but above all adapting to each other.

The story of mutual adaptation and response begins before the chronological remit that this book has set itself. The last ‘Ice Age’, equated in Britain with the Devensian cold stage, reached its maximum in terms of ice cover around 18–20,000 BP. [That is, ‘years Before Present’. Where we use calibrated radiocarbon dates or precise calendar dates, the forms ‘cal. BC’ and ‘AD’ are used]. Although it is naive to suggest that the Devensian ice-sheet had a clearly-defined boundary, the southern limit of the ice can be imagined as a line extending roughly from the Severn Estuary to the Humber (Jones and Keen 1993). North and west of that line lay ice sheets, with just the frost-shattered tops of the highest mountains protruding. To the south and east lay a barren land of meltwater streams and lakes, seasonally frozen, and swept by cold winds circulating around the ice sheets. Again, it would be simplistic to imagine even that stark landscape as completely devoid of animal life, but the Devensian ice maximum must have represented a point at which Britain supported only a very sparse fauna of tundra specialists, and much of that perhaps only seasonally (Currant and Jacobi 2001; Schreve and Currant in prep.). The limiting factor was not simply temperature. The dynamic and unstable environment south of the ice could not develop soils of any depth or duration. Without those soils, colonisation by even cold-tolerant plants was severely limited. Without the plants, herbivores could not persist, and without herbivore prey, neither could the predators.

The eventual wasting of the British ice sheet was probably a far more complex affair than is generally allowed, with rapid retreat in places matched by sudden surges of ice advance in others. Suffice to say that extensive wasting of ice cover was underway before any substantial temperature rise, and the collapse of the ice sheets may have had as much to do with a loss of precipitation as with temperature (Lowe and Walker 1997). Between about 15 and 14,000 BP, temperatures in northwest Europe did rise, and quite sharply. A short-lived warm spell (the Late Glacial Interstadial) allowed some recolonisation by temperate flora and fauna, and also seems to have attracted people back into Britain (Barton et al. 2003; Blockley 2005; Lord et al. 2007). Temperatures then fell, first gradually, then, around 12,500 BP, rather sharply. An acutely cold but dry stage (the Late Glacial Stadial, or Younger Dryas) brought permafrost conditions though relatively little ice cover to much of Britain. Some of the larger animals that had successfully colonised during the Interstadial may have adapted to the periglacial tundra conditions whilst others were rendered at least locally extinct. Finally, a little before 11,000 BP, a sudden climate warming ushered in the present post-glacial period, bringing fully temperate conditions in less than a century.

The important point about the various climate swings of the Late Glacial period is that communities and ecosystems were repeatedly disrupted. From 15,000 BP onwards, the fauna of Britain must have been continuously in a state of disequilibrium. Even when temperatures settled for a millennium or so, vegetation communities would have taken longer to respond, and animal communities were constantly adapting to changes of vegetation cover and distribution, as well as to changes of temperature and seasonality. To that dynamic background must be added a landscape which was itself adjusting to the removal of ice, exposing new terrain and drowning large areas under meltwater lakes, with meltwater channels superimposed onto older drainage systems to produce new patterns of ridges and valleys to confront migratory animals. Finally, the combined effects of meltwater pouring into the oceans and land rebounding following the release of ice pressure led to the relative levels of land and sea undergoing diverse adjustments, one of which eventually allowed the sea to transgress through the wide river valley that we now know as the English Channel to meet up with the flooded lowlands that became the North Sea (Preece 1995). By about 8000 BP, Britain was an island, and patterns of seasonal migration and of recolonisation were radically altered.

Just as a lack of vegetation cover in the Late Glacial must have been a major factor in the fauna of that period, so the recolonisation of Britain by temperate flora, and the development of often transient vegetation communities, must have had a marked effect on the post-glacial fauna. Pollen analysis, often backed up by plant macrofossil evidence, gives us an indication of the broad pattern of events by which tundra became temperate woodland, though the detail clearly varied considerably from patch to patch. A common feature of many pollen diagrams early in the post-glacial is the dominance of birch pollen, sometimes with a secondary component of pine. This is generally taken to indicate a stage of rather sparse woodland, predominantly of birch (Betula spp.) as these species produce abundant seeds that are readily spread by the wind, and are well adapted to the colonisation of rather thin, young soils. In most pollen sequences, this birch-dominated phase is quickly followed by one in which hazel (Corylus avellana) is abundant, itself superceded by a more familiar mix of deciduous woodland, with oak (Quercus spp.), elm (Ulmus spp.), and alder (Alnus glutinosa). The mixture of species and predominant tree species seems to have varied between localities, with lime (Tilia europaea), for example, being a significant component in some regions (e.g. see Fyfe et al. 2003).

The palaeontological record for the first couple of millennia of the post-glacial shows a fascinating mix of temperate large vertebrates, such as red deer (Cervus elaphus) and wild cattle (Bos primigenius), alongside species that may be thought of as more typically Late Glacial relict species that went extinct only rather gradually, such as elk (Alces alces) and reindeer (Rangifer tarandus). Although that may be an over-simplistic analysis, the key point is that the temperate woodland environment that gradually established during the early post-glacial was populated by a greater diversity of large grazers and browsers than was the case later in the post-glacial. Although the details can only be speculation, it is likely that this browser community had a general effect on the patchiness of woodland colonisation and a local effect on the distribution and extent of some tree and scrub communities. There was probably some establishment of clearings and ‘trails’ by grazing and browsing pressure alone. Into this environment, too, came people, drawn by the herds of large prey and diverse plant resources inland, and by the diversity of littoral resources on coastlines still equilibriating to changing sea level (Bevan and Moore 2003; Mannino and Thomas 2002). People were a clearance pressure on the vegetation, through fire and deliberate felling, and a predation pressure on the animals. How significant a predation pressure is the subject of speculation and theoretical modelling: here we may note that the three big predators of Late Glacial Britain – brown bear (Ursus arctos), wolf (Canis lupus) and lynx (Lynx lynx) – all persisted into the post-Roman period, which suggests that they survived pressure from human changes to the landscape for millennia before their eventual extinction through habitat loss and active persecution.

Once the colonisation and environmental turnover of the early post-glacial stabilises in the pollen record, it is tempting to equate the near-stasis of that record with environmental stability and predictability. That in turn leads to an attitude that not much happened, at least in environmental terms, through much of the Mesolithic. However, we have to acknowledge that our main source of evidence, the pollen record, is generally useful for large-scale, medium-term environmental change, but usually less useful for spatially-limited, short-term impacts. The period between about 8500 and 6000 BP may have seen frequent local clearances of woodland by people, with consequences for deer, boar (Sus scrofa), squirrels (Sciurus vulgaris), voles (Microtinae), lynx, woodland birds and leaf-litter invertebrates, or changes caused by fluctuations in browsing pressure, with consequences for people (Mitchell 2005). Only rather rarely is the pollen record of sufficient spatial and temporal precision for us to be confident that we would pick up any such local events, still less for us to be confident that we could rule out the possibility (Davies and Tipping 2004). The post-glacial wild-wood must have undergone patchy clearance through many different agencies, and the impression of stasis that we often get from the palaeoenvironmental record is probably misleading. It is important to keep this point in mind, because the next notable environmental impact in the post-glacial is, according to our point of view, either the most significant environmental change in the entire post-glacial period, or just another form of clearance.

Around 6000 BP, people in Britain began farming and the fauna of Britain was supplemented by the addition of domestic cattle, domestic sheep and (probably) goats (Capra hircus), and domestic pigs (Sus scrofa): two grazers and a broad-spectrum omnivore that is conspecific with a native species. To qualify that bold statement, the date is only approximate, based on just a handful of sites with early, directly-dated specimens of domestic animals. Furthermore, it is not clear whether the people concerned were immigrants from parts of Europe in which farming was already well-established, or whether they were ‘locals’ who adopted a new way of life (Rowley-Conwy 2003). And it is not clear whether ‘farming’ at this early date really means anything more than the casual ranching of some new species alongside the continued hunting of deer and boar, and collection of shellfish (Rowley-Conwy 2004). Finally, it increasingly looks as if farming entered Britain not by way of south-east England, as has traditionally been implicitly believed (after all, it is the bit of Britain closest to the rest of Europe), but through the Atlantic and Irish Sea coasts, probably from Iberia and western France (Haynes et al. 2003; Innes et al. 2003).

With the first domestic mammals came arable crops, principally barley (Hordeum spp.) in the north and west of the country, and more cultivation of wheat (Triticum spp.) towards the south and east (Fairbairn 2000). To what extent this led to wholesale clearance of woodland is hotly debated, with the consensus moving away from a ‘fields of waving corn’ model for Neolithic farming towards something more shifting and intermittent (Jones 2000; Thomas 2004). Even allowing for that adjustment in our understanding, some clearance for arable agriculture evidently did take place, and to that must be added clearance for monument construction, clearance as monument construction, clearance as a consequence of grazing, and clearance by the extraction of building timber and firewood. By the end of the Neolithic, 4500 years ago, at least the landscape of the southern part of Britain was a substantially more open than it had been when the first domestic animals arrived. Here and there, some evidence for secondary regrowth of woodland has been adduced. For example, on the chalklands of central southern and eastern England, sedimentary sequences from the ditches of Neolithic monuments such as causewayed enclosures and barrows commonly show a phase of scrub or tree regrowth around the end of the Neolithic (Evans 1971; 1990; 1999). This has been interpreted as showing ‘abandonment’ of the monuments and, by implication, some lessening of clearance pressures in the surrounding landscape. The evidence, of course, relates to the monuments themselves, and it could equally be argued that the regrowth of scrub and trees over and around important places was tolerated, even managed, in a quite deliberate attempt to maintain their visibility and distinctiveness within what was otherwise becoming a more open landscape.

Elsewhere in Britain, two very distinctive landscapes were developing by the Bronze Age. Across the higher ground of northern and western Britain, blanket peat was extending across what had been areas of mineral soils, at least some of which had previously been settled and farmed; for example, at Scord of Brouster, Shetland (Whittle 1986). This peat expansion may have been partly driven by climate change, a shift to cooler and wetter conditions inhibiting the decay of plant litter and thus initiating the growth of peat. Prehistoric land use may also have played a part, in particular the removal of the deep-rooted trees and shrubs that recycle nutrients from deep in the sub-soil to the surface in their leaf litter whilst maintaining drainage through their deep root systems (Moore 1993). Whichever factor drove blanket peat growth in any particular area, the consequence was the development of a highly distinctive and biotically unproductive environment, distinctive today for the dominance of ling (Calluna vulgaris) and other ericaceous plants, and a sparse vertebrate fauna amongst which red grouse (Lagopus scoticus) is particularly iconic. The other distinctive environment developed along the Atlantic seaboard, most especially along the western coast of Scotland and the Hebridean islands. Here, as sea level change gradually stabilised, wave action and prevailing onshore westerlies led to the accumulation of sand in extensive dune systems (Gilbertson et al. 1996). The sand was predominantly derived from comminuted shell, thus giving rise to a soil parent material that is both sharply drained and calcareous, in a part of the country in which mineral soils otherwise tend to be either highly leached or peat-based and acidic. Where the dunes were stabilised by soil formation and plant growth, the distinctive machair environment developed, giving rise to some of the most fertile agricultural land in northern Britain. Like the peat uplands, this environment developed its own distinctive fauna, characteristically including corncrakes (Crex crex) and, during the last millennium, copious rabbits (Oryctolagus cuniculus).

Across much of lowland Britain, later prehistory saw more and more land taken into agriculture and closely managed. The archaeological record shows field systems pushing into upland regions, and colluvial infilling of valleys reflects the instability that repeated ploughing brings to even quite gentle slopes (Allen 1992; Bell 1983; 1990). It is debatable just how much of the original post-glacial woodland had been cleared for farming by the dawn of the Roman occupation, but what remained must certainly have been highly fragmented. That fragmentation, with the consequent isolation of woodland faunas in small patches and small populations, must itself have been of some ecological consequence, leading to local extinction of some woodland species simply through the isolation of unsustainable populations, rather than through any deliberate extirpation. Woodland specialists such as pine marten (Martes martes) are likely to have been particularly vulnerable to such fragmentation. Conversely, by the end of the Iron Age, Britain was well-connected to the rest of Europe through sea-borne trade and exchange. House mice (Mus domesticus) and chickens (Gallus gallus) entered Britain during later prehistory, but it was during the Roman period that the potential for the introduction of new species, either deliberately as cargo or inadvertently in cargo, really increased. In part, this was because of the sheer increase in the volume of human and cargo traffic back and forth between Britain and the near Continent. In part, too, the establishment of a road network must have played a part in allowing species newly introduced through ports and distribution centres such as London, Gloucester, Chester and York to be rapidly disseminated. Just as all roads lead away from Rome, so the road system in Britannia tended to lead to and from relatively few foci.

In terms of overall environmental impact, the Roman occupation probably made little difference to Britain. Lowland regions were extensively grazed and intensively ploughed before the legions arrived, and continued to be so through the four centuries of Roman rule. Species that were vulnerable to the loss of woodland habitat or disturbance of grassland through grazing pressure were likely already to have been reduced in number or distribution during later prehistory, and the fragile habitats of the northern and western mountains and islands were hardly touched by Roman management. Even along the line of Hadrian’s Wall, a major construction and the base for numerous troops, it is questionable whether the Roman activity had a discernible impact on the surrounding landscape (Dumayne and Barber 1994; 1997; McCarthy 1995). The Roman impact on the British fauna was more in terms of introductions. Some were exotic animals, introduced in small numbers and probably never truly established in Britain as viable populations. As later chapters in this book show, pheasant (Phasianus colchicus), guinea fowl (Numida meleagris), fallow deer (Dama dama) and rabbits (Oryctolagus cuniculus) may all fall into this category. One Roman introduction that clearly did settle in, at least for a few centuries, was the black rat (Rattus rattus), presumably an accidental introduction (O’Connor 1991a; 1992), and the same inadvertent transport may explain the few records of garden dormouse (Eliomys quercinus) (O’Connor 1986a). Vermin and exotic pets aside, the Roman impact was largely in the construction of towns, with the consequent creation of new urban habitats and communities. This was the environment into which black rat moved with evident success, and it is likely that a wide range of invertebrates established themselves in towns. Some of these will have been endemic species that adapted successfully to the new opportunity, whilst others will have been imports such as grain pests (Carrott and Kenward 2001).

Britain is often presented as having entered a Dark Age following the collapse of Roman rule, but in terms of the environment in general and fauna in particular, this is probably misleading. Certainly the towns reduced in population and thus in the nature of the highly specialised environment that they represented. Change in the countryside during the fifth to eighth centuries AD is more difficult to assess, mainly for want of evidence. Farming patterns, and thus the specific pressures on different patches of land, may have changed, but the country was still populated, and a mixed farming economy persisted. By the late ninth and tenth centuries, some of the old Roman town centres were being re-occupied, and new towns were established, giving rise to a diversity of urban habitats and niches. Although it seems likely that lowland Britain was still largely open pasture, meadow and arable, towns such as York could be rebuilt largely in timber, some of it from substantial trees of a considerable age (Hall et al. 2004). The next major environmental impact, and the one that finally established rural Britain as we know it from the historical sources, came in the aftermath of William the Conqueror’s seizure of the throne in AD 1066. With the establishment of baronial estates came two significant changes: the organisation of substantial tracts of land into hunting forests and, later, the introduction of rabbits. The first embodied the concept that the ‘wild’ should be managed, a concept that subsequently drove the British gamekeeping tradition and its practice of extirpating species that might compete with or predate the prey animals that were raised and ma...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Contents
• Preface
• Contributors
• List of Figures
• List of Tables
• 1. Introduction - The British Fauna in a Changing World
• 2. The Horse
• 3. Donkeys and Mules
• 4. The Aurochs and Domestic Cattle
• 5. The Elk
• 6. Red Deer on Scottish Islands
• 7. European Fallow Deer
• 8. The Wild Boar
• 9. The Wolf
• 10. The Lynx
• 11. Wildcats, Domestic and Feral Cats
• 12. The Brown Bear
• 13. The European Beaver
• 14. The Rabbit
• 15. The House Mouse
• 16. The Black Rat
• 17. Extinct Birds
• 18. Bird Introductions
• 19. Freshwater Fish
• 20. Land and Freshwater Molluscs
• 21. Insects
• 22. Conclusion
• Bibliography
• Index