Hard-up biology departments are cutting field courses. Peter Cotgreave credits them with teaching him to think logically and scientifically and makes a plea for their retention. A friend who teaches ecology in a British university told me that the fieldwork component of the biology course is about to be cut quite heavily, having already been reduced a few years ago. "It's a shame," he said, "but we can't afford it any more."

My impression is that my friend is not alone. As class sizes grow and as each pound spent on higher education must be used more and more efficiently, labour intensive field courses are becoming a luxury.

When I studied for my first degree a decade ago we not only had an excellent week-long field course at the end of the first year, we also had field-based practical classes of one sort or another throughout the course. I learned more during those field studies than in any other part of the course, not just in terms of information, but also in understanding and appreciation of how the biological world works. Without that understanding, all attempts to teach me how to think logically and scientifically about my subject would have failed hopelessly.

Yet when I received a set of comments on a grant proposal recently, one of the referees thought the project was interesting but, in the absence of any information, was unsure whether I had "good field sense". I can have no complaint about these remarks. There is no way the referee could have known about my field skills because most of my published work has been mostly of a more theoretical nature, with only a couple of field-based papers. But, on reflection, it seems a shocking indictment of the state we have reached when one cannot assume a good sense of field biology in someone who has a first-class degree in biology, a PhD from a zoology department and has worked as a lecturer in ornithology.

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I do not mean to imply that all biologists must be good field biologists. Indeed, many significant contributions in biology have been made by theoreticians whose formal training has been in other disciplines, such engineering, mathematics or sociology.

Enormous leaps forward have been made in evolutionary biology by people working with systems where the study organisms have been kept in the laboratory for many generations. Nor would one seek to deny the molecular revolution that has meant that intricate, laboratory-based techniques are throwing light on every aspect of ecology and evolution. Field studies are not the only kind of biology, nor are they the only way of learning about ecology or evolutionary biology. But that is not the point. We ought not to be able to cut out field courses and field-based practicals in our biology degree courses any more than we can suddenly pretend that it does not matter if our students do not understand Darwinian evolution or the principles of genetics.

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A colleague who takes a different view says that practical work of all kinds is unnecessary because we should teach students how to think, not merely how to wash up petrie dishes or count plants in quadrats. The best student he ever encountered, he says, never attended a single practical class of any sort. That may well be true, and the student concerned has certainly gone on to make a major contribution to biological science. But I would answer his erstwhile tutor in two ways.

First, the greatest contribution to biological thought ever was made more or less simultaneously by Charles Darwin and Alfred Russel Wallace. Neither of them would have unravelled the mystery of evolution without extensive field observations.

Second, we do not only have responsibilities to those students who are the brightest thinkers. There are many different kinds of students and we cannot design our courses around the needs of all of them. For those who wish to become theoretical biologists, merchant bankers or househusbands after a degree in biology, my colleague is right - it is not the particular skills or information that matter, it is unlocking the thrill of learning, of thinking and of reasoning.

However, many students of the biological sciences want to become teachers, or enjoy a career in practical biology. A large proportion will never use their wellington boots once they have graduated - even some of those who become professional biologists. But equally, a large proportion will never worry about how a kidney works, or work out what proportion of a population is expected to carry a particular gene. And surely an undergraduate education in biology should include the needs of those who want to become academic zoologists, or botanists, or evolutionary biologists or who want to work as ecological consultants or environmental lawyers.

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A glib answer to the problem would be to tell the student who is interested in field biology to study for a degree in ecology or environmental science. But that is of no use to the potential biology teacher, who needs to know about population genetics and how kidneys work. Nor is it any great help to the 18-year-old who knows she has an interest in biology but has yet to discover which parts of the subject fascinate her most.

I have seen students come into their own on field courses, after terms of coursework that has been mediocre to say the least; they suddenly realise how all their lecture notes relate to real organisms. And, invariably, such students retain that excitement and interest when they return to the library, the laboratory or the lecture hall. They sometimes turn out to be among the best performers of their year group.

There is no easy solution. Field courses are both expensive and labour intensive. There is no point in pretending that undergraduate education is awash with money, or that we can ever hope to return to some mythical 1960s' Utopia when there were trips to the seaside for everyone.

Moreover, other (equally important) areas, such as laboratory skills, are becoming increasingly complex and increasingly expensive, both to do and to teach. Some would say it is wrong to starve them of resources just to satisfy our desire to include fieldwork in the curriculum. However, I do know that marking field-course reports gives a better impression of a student's overall mark in their final exams than probably any one of their other papers.

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Whatever else we are forced to cut back on, we must make sure our students are being taught the practical, field-based observation skills that helped Darwin to give us the greatest contribution to biological science that anyone has ever made.

Peter Cotgreave is a conservation biologist at the Institute of Zoology, Zoological Society of London.

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