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Book Review – Islands (New Naturalist 109) by R J. Berry

by Gordon L Woodroffe
originally published by the Yorkshire Mammal Group.

Collins 2009, ISBN 978-0-00-726737 £30 hbk, ISBN 978-0-00-726738 £20 pbk

The New Naturalist books were the brainchild of William Collins, managing director of the family publishing business. As long ago as 1943, during World War II, Collins decided he needed a team of distinguished naturalists to draw up a list of titles and find the right authors for them so as to ensure the highest scientific and literary standards This has proved to be a publishing phenomenon

It says much for the success of the series that after all these years titles are still being added. Islands (NN 109) by R J ‘Sam’ Berry is one of the latest. Sam was Professor of Genetics at University College, London. He is a well established NN author having written such volumes as: Inheritance and Natural History (1977); The Natural History of Shetland (1980) with Laughton Johnston; and The Natural History of Orkney (1985).

Islands, his fourth book, draws together studies on these and many other islands. Berry’s island research began with studying moths in 1959 and then a 10 year study of House Mice on Stokolm followed by more island research. There is little doubt that the author has been drawn to the excitement and magic of islands: “islands have an ethos of their own but the infection of ‘islomania’ has never completely disappeared.” Nonetheless this is a huge subject to cover in one volume, so inevitably some islands receive much more attention than others.

What constitutes an island and how they are formed make interesting opening chapters. Another, on island pressures, describes how island species have to 'make do' with a niche different to their normal one and that islands tend to have fewer species than mainlands.There is also a change in size of island mammal species when compared with their mainland relatives; apart from rodents they tend to be smaller than their counterparts. Island life brings with it an ecological frailty, 75% of all known extinctions have occurred on islands. Moreover, island biota are far more vulnerable than mainland ones, particularly to invasions by predators and competitors. Globally, islands have suffered enormously by introductions The worst culprits are four rodent species: the ship or black rat; the common or brown rat; the house mouse; and the Pacific rat (the last was intentionally spread to many Pacific islands). While feral goats although being a major pest on many oceanic islands do not seem to cause significant damage on British islands. Mink, on the other hand, have proved highly destructive on the Outer Hebrides and hedgehogs pose a serious threat to ground-nesting birds.

What are the consequences of life on islands? The key questions look comparatively simple; how and when did the inhabitants of a particular island get there'? Are they just managing to hang on or are they a significant part of the biota. Mammologists will find that these factors have been most studied in small mammals. Often island populations of small mammals (e.g. rodents) show an increase in average size; frequently they have higher and more stable densities than on mainlands; they may show behavioural differences. These topics are well covered and lead to the theory of island biogeography and genetics. The differentiation of British and Irish island forms of field mice and house mice receive comprehensive treatment based on the author’s own research.

Some prominent islands receive detailed attention However, in the Shetland section otters hardly get a mention which is most surprising as the Shetland otter population was rigorously studied and has provided a baseline to our present understanding of otter ecology.

The final chapters: Island Naturalists and Facts Fancies and Fragilities make an interesting conclusion to a worthy addition to the “New Naturalist phenomenon”.

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