Bird-brained theories

Is modern farming chasing birds from the hedgerows?

Tony Gilland

Topics Science & Tech

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The debate continues about the future of GM crop technology in the UK and the implications for farmland biodiversity of growing GM crops on UK soil.

It is important to remember that the UK farm-scale evaluation (FSE) trials (1), currently being considered by the government’s Advisory Committee on Releases to the Environment (ACRE), were initiated at a time when modern farming techniques were maligned by conservation organisations for having a negative impact on farmland bird populations. Few critical questions have been asked of this influential, but simplistic, perspective on the relationship between farming and wildlife.

Consider this English Nature press release from 10 December 1999: ‘”A 35 per cent decline in farmland bird populations between 1973 and 1998 obviously flashes a warning signal that current agricultural practices are not sustainable”, said Baroness Young of Old Scone, English Nature’s chairman. The gradual erosion of the traditional relationship between farmers and wildlife, through the intensification and specialisation of farming methods, has drastically reduced the biodiversity of England’s farmland.’

Four years on, with the conclusion of the trials, LG Firbank et al argue in their commentary on the FSEs that the possibility of reduced populations of arable weeds ‘exacerbating declines in birds that feed on weed seeds…needs to be taken into account when assessing the impacts of growing these crops’.

If we are to have a fair assessment of the management practices associated with the three GM crops studied in the FSEs, then we need to discuss and debate more critically the prevailing preoccupation with farmland biodiversity, and in particular the headline-grabbing discussion about farmland birds.

All too often ‘farmland biodiversity’ is referred to as a self-evident good, and its decline as a self-evident bad, without any proper explanation of what mix of organisms we are concerned about and why. To the extent that a specific argument is made for the importance of farmland biodiversity, it is often done in relation to human enjoyment of the British countryside and with particular reference to the British public’s love of birds.

However, the contemporary debate about farming and bird populations is heavily coloured by a tendency to overemphasise the destructive nature of human activity. An examination of this debate provides a useful case study in the cultural framing of questions about farming and wildlife, and how this is usually done in a one-sidedly negative way.

The population levels of different bird species within the UK have always been subject to change in response to changes in human activity. Changing bird populations are neither new, surprising or worrying. There is a danger that for cultural and political reasons we are becoming overly sensitive to having any impact on other species. Consider the following points:

  • An authoritative review of historical ornithological literature conducted in 1944 found that ‘132 out of 189 breeding species, or 70 per cent, have changed markedly in status during the course of the nineteenth and twentieth centuries’. The authors noted that widespread species ‘could probably double or halve its numbers without the fact being noticed’ (2). Today a 25 per cent recorded decline in a bird species prompts a Biodiversity Action Plan being put into place; it seems that today’s government is unwilling to allow bird populations to fall as well as increase, though this has always been the way of things.
  • The number of species breeding in the UK is thought to be around 20 per cent greater today than in 1800, despite the intensification of agriculture on the 75 per cent of the UK’s land surface that is farmed. ‘The number of breeding species in the UK is increasing, with nearly 40 more species breeding at the end of the twentieth century than at the beginning of the nineteenth…. In the last 30 years there has been a net increase of four species per decade.’ (3)

But is there a particular problem with Britain’s farmland birds? The answer to this depends on what you count as a farmland bird. If you count birds found on farmland and accept that some bird populations will fall while others rise, it is hard to justify the way in which modern farming has been blamed for producing a sterile countryside devoid of birds. To date, the data provided in this debate has been highly selective. Alarming statistics about the decline of farmland birds are dependent on a more specific definition of what a farmland bird is. It is worth taking into account that:

  • The 35 per cent decline in farmland bird populations between 1973 and 1998 statistic in the English Nature press release quoted above refers to the DETR’s ‘farmland bird’ index (part of its quality of life series of indices). This is a composite index of the recorded population changes of 20 birds found breeding on farmland and deemed to be ‘farmland specialists’. However, a similar composite index that included all of the 42 bird species for which Siriwardena et al calculated a farmland index would show either no overall change or a slight increase (4). In other words, if we counted all the bird species found on farmland, as opposed to those singled out as farmland specialists rather than generalists, we would not get the dramatic ‘35 per cent decline’ statistic. Of the 42 species found on farmland, 18 have declined by more than 20 per cent over the past 30 years and 17 have increased by more than 20 per cent over the same period.
  • What’s special about the specialists? For some of the so-called ‘farmland specialists’ – skylark, starling, tree sparrow, greenfinch, goldfinch, linnet, and reed bunting – research has estimated that between 35 per cent and 65 per cent of their populations breed on non-farmland habitats (5).
  • Modern farming has been blamed for the downfall of some ‘farmland specialists’ without any specific evidence that this is the case. Take the plight of the tree sparrow, which has featured prominently in conservationists’ publicity as a victim of intensified farming, as a result of its startling 87 per cent decline over the past 30 years or so. Even English Nature’s own Biodiversity Action Plan, published in 1998, states that: ‘The tree sparrow appears to undergo irregular fluctuations in numbers. In Britain there was a high population from the 1880s to the 1930s, but numbers then decreased to a low point around 1950…. Numbers then increased again from 1960 to 1978, possibly due to an influx of birds from mainland Europe…. Little is known about the factors affecting numbers of tree sparrows.’

If we are going to have an intelligent discussion about the implications of the FSEs for the introduction of commercially grown GM crops to the UK, we need to discuss what aspects of farmland biodiversity are important and why, rather than assume that farmland biodiversity in general is a good thing. Nobody would argue that we should encourage the greatest possible diversity of species on farmland, since this would negate the whole purpose of farming – to improve upon the lot of the hunter and gatherer who was dependent on what nature had to offer.

Obviously, a large part of the current discussion, and the motivation behind the FSEs, is about whether there is too little biodiversity on farmland in the UK. But what is the benchmark, what should we be trying to achieve? Which species, other than the crops being grown and those that are important to their growth, merit our attention, and why?

Certainly in relation to bird populations, which do provide an eye-catching backdrop to this discussion, the debate to date has been alarmist and one-sided. As Lord Derek Barber, former chair both of the RSPB and the Countryside Commission, told me back in 1999: ‘In terms of a balance sheet type approach, conservation is gaining something every day. What people ignore is the fact that we are getting better rather than worse. Everything as far as the RSPB are concerned is always in grave danger. Bodies like the RSPB and WWF cry wolf at every opportunity. They tend to go for exaggerating all the time and they tend in due course to believe their own exaggeration.’

Tony Gilland is science and society director at the Institute of Ideas. He is the editor of Science: Can You Trust the Experts?, Hodder Murray, 2002 (buy this book from Amazon (UK) or Amazon (USA)); Animal Experimentation: Good or Bad?, Hodder Murray, 2002 (buy this book from Amazon (UK) or Amazon (USA)); and Nature’s Revenge?: Hurricanes, Floods and Climate Change, Hodder Murray, 2002 (buy this book from Amazon (UK) or Amazon (USA)). He is also a contributor to Rethinking Risk and the Precautionary Principle, Butterworth-Heinemann, 2000 (buy this book from Amazon (UK) or Amazon (USA)).

Read on:

spiked-debate: The future of GM – why do we need the UK farm-scale trials? (September to October 2002)

spiked-issue: Genetics

(1) See the GM crop farm-scale evaluations on the DEFRA website

(2) Alexander and Lack, 1944

(3) The State of the UK’s Birds 1999, Gregory et al, RSPB, 2000

(4) Journal of Applied Ecology 1998, 35:24-43

(5) R Gregory 1999; Journal of Applied Ecology 1998, Vogelwelt 120: 47-57 and Gregory and Baille, 35:785-799

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Topics Science & Tech


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