Bird Populations
Earlier naturalists formed the impression that bird numbers remained more or less stable through time. In the years since these words were written, however, changes have occurred in the landscapes of the British Isles and in the seas around our coasts, causing bird populations to fluctuate in an unprecedented way.In Ian Newton’s latest New Naturalist volume, he explores bird populations and why their numbers vary in the way they do, from year to year or from place to place. He addresses the various factors that we know limit bird numbers – food supplies and other resources, competitors, predators, parasites and pathogens, and various human impacts.The combination of a rapidly expanding human population, a predominantly utilitarian attitude to land, central government policy on land use, and increasing mechanisation have combined to promote more massive changes in land use – and hence in bird habitats – in recent decades than at any comparable period previously. These developments have in turn brought huge changes in bird populations, as some species dependent on the old landscapes declined, and others benefiting from the changes increased. Over the same period, changing public attitudes to wildlife, protective legislation and a growing network of nature reserves allowed previously scarce bird species to recover from past onslaughts, while climate warming has promoted further changes.In this seminal new work, Ian Newton sets out to explain why different bird species are distributed in the numbers that they are, and have changed over the years in the way that they have. He emphasises the factors that influence bird numbers, rather than the numbers themselves, thus providing a much-needed overview which is necessary if we are to successfully manage bird populations, whether for conservation reasons, for sustainable hunting or for crop protection. The continued monitoring of bird numbers can also alert us to impending environmental problems. In addition, the regular watching and study of birds now provides a source of recreation and pleasure for very large numbers of people, who would find a world with fewer birds a poorer place.
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EDITORS
SARAH A. CORBET, SCD DAVID STREETER, MBE, FIBIOL JIM FLEGG, OBE, FIHORT PROF. JONATHAN SILVERTOWN
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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.
Contents
Authorâs Foreword and Acknowledgements
3 Food Supplies: General Principles and Individual Impacts
4 Food Supplies: Population Impacts
6 Predation: General Principles and Individual Impacts
7 Predation: Population Impacts
8 Parasitic Diseases: General Principles and Individual Impacts
9 Parasitic Diseases: Population Impacts
10 Competition between Species
11 Interactions between Different Limiting Factors
12 Interactions between Predators and Resources
13 Interactions between Parasites and Resources
FOR THIS, HIS THIRD NEW NATURALIST volume after Finches (NN55) in 1972 and Bird Migration (NN113) of 2010, Ian Newton has again elected to review a major component of the biology of birds in general rather than dealing, as has been the norm in this series, with all aspects of the life of a group of related species.
Bird populations are moderated from year to year by the balance (or indeed the imbalance) between recruitment during the breeding season and mortality, mostly but by no means exclusively during the winter months. Beneath this superficial simplicity lies the substance of this volume. In 20 chapters, Professor Newton explores and reveals the vast array of varied and often interacting factors that can influence bird populations. The first part of the text is devoted to the range of natural factors influencing bird numbers, from food and nest site availability to predators and parasites, and on the impact of interspecific competition. The section closes with three chapters on the often intriguing interactions between these various natural limiting factors.
Although the chapter entitled Weather relates to natural influences, in Climate Change a human impact becomes evident, and human influences are more obviously apparent in the remaining chapters devoted to hunting and to the often seemingly disastrous problems caused by pesticides and other pollutants. Sobering, even alarming, as this must appear to todayâs reader, in his closing chapter Reflections, Ian Newton emphasises that despite the âmodernâ problems caused by man and his rapidly developing technologies, most birds today are limited by ânaturalâ factors, whereas a century ago âmany (perhaps most) bird species in Britain and Ireland were limited by human killingâ.
Professor Newtonâs credentials for addressing the comprehensive analysis entailed in this volume are impeccable. A Fellow of the Royal Society, his working career was spent in governmental research, starting with the old Nature Conservancy, which through a series of (taxonomic) changes became the Institute for Terrestrial Ecology at Monks Wood, sadly now no more. His international standing in avian ecology has been recognised by service as President of the British Ecological Society and of the British Ornithologistsâ Union, by an Honorary Fellowship of the American Ornithologistsâ Union and as Chairman of the Royal Society for the Protection of Birds and of the British Trust for Ornithology, and to his appointment as OBE.
We are fortunate in Britain and Ireland, as Ian Newton notes, that modern ornithology benefits from a range of comprehensive censuses and surveys that draw on the wealth of records available from skilled amateur ornithologist volunteers. These offer to ornithological researchers interested in understanding the mechanisms and implications of population changes opportunities not available to zoologists in other disciplines. The New Naturalist is doubly fortunate that Ian Newton is admirably placed to review, as an active and life-long participant in many of them, the results of these researches and to distil them thoroughly and lucidly to an appreciative readership. This volume is a noteworthy and most welcome addition to The New Naturalist Library.
THIS BOOK IS ABOUT BIRD NUMBERS, and about why these numbers vary in the way they do, from year to year or from place to place. It is therefore concerned with the various factors that limit bird numbers: with the role of food supplies and other resources, of competitors, predators, parasites and pathogens, and of various human impacts.
Earlier naturalists, with less information at their disposal, formed the impression that, despite annual fluctuations, bird numbers remained more or less stable through time. Species that were common remained common, while species that were rare remained rare. In his influential book on
