Leseprobe © Westarp Wissenschaften 2012 the eurasian red squirrel Sciurus vulgaris First edition stefan Bosch Peter W. W. lurz Leseprobe © Westarp Wissenschaften 2012 With 81 illustrations and 14 tables cover photo: red squirrel eating on a tree stub in the montane forest of Davos (switzerland). Foto: Bosch All rights reserved. this book is protected by copyright. No part of this book may be reproduced in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, scanning or otherwise, or used by any information stor- age and retrieval system without written permission from the publisher. © 2012 Westarp Wissenschaften- Verlagsgesellschaft mbh, hohenwarsleben http://www.westarp.de commissioning editor: Dr. günther Wannenmacher copy editor: elisabeth gräfin von Westarp Production manager: Alf Zander Printer: Westarp & Partner Digitaldruck hohenwarsleben ug, germany Leseprobe © Westarp Wissenschaften 2012 Foreword A sunday walk to enjoy the beautiful colours of autumn in a woodland near town. A slight rustle among fallen leaves; pausing, we see a red squir- rel making little jumps, apparently undecided which direction it should take. it stops, sitting on its hind legs to look around, the ears, adorned with long elegant eartufts, seem like antennae to capture the lightest of sounds that could mean ‘danger’. the squirrel is carrying a hazelnut in its mouth. suddenly it jumps again and then pushes its muzzle against the earth, shaking the head; it looks up, the hazelnut has disappeared. the squirrel makes fast tapping movements with its front paws, looks up again, sees us, and with a chattering sound hurries up the nearest oak tree, hiding on the opposite side of the stem from where we are standing. this is certainly one of the most likely ‘close encounters’ an attentive hiker can have with a mammal in forests and woodlands all over europe. in fact, being day-active, the red squirrel is one of the most attractive and easily spotted animals in our forests. unfortunately, in some places, like on the British isles and parts of North italy, this is no longer the case and i will come back to this later. For any man or woman interested in nature and its amazing creatures such an observation would make them wonder: what is it doing and why? An- swers to this question and many others can be found in this book. i have been a squirrel biologist for several decades. i made my first steps in squirrel research in 1983, for my bachelor thesis, and have never subse- quently abandoned them. Although i always keep myself updated with the scientific literature on red and other squirrel species, i remain amazed at the amount of information given in this book: it contains nearly everything ever written about the red squirrel. there have been several other volumes dedicated to our favourite tree ac- robat but never one so extensive. Whether the one who opens this book is a squirrel specialist, a professional biologist, an amateur naturalist or a casual reader, she or he will not only discover many new facts about its evolutionary origins, how a squirrel is ‘built’ and how it spends the day, but also understand how nuanced the interactions between this animal and its environment are. how, for example, stone pines depend on red squirrels for seed dispersal and germination. squirrels bury many of their seeds to Leseprobe © Westarp Wissenschaften 2012 8 Foreword have energy-rich food stores the next spring, but do not recover all of them. how squirrels, on their turn, depend on how many seeds the trees have produced that year to find enough food to meet the high energy demands for a female to produce young. the quite astonishing fact that red squirrels seem to be able to anticipate a mast-crop, starting to breed in large num- bers before the enormous amount of energy-rich seed become available. All this is the result of a long story of natural selection to a hard and changing environment that has led to a co-evolution of squirrels and (some of) their food plants and that has made the red squirrel what it is today. reading the chapter on the evolutionary history of sciurid rodents and the distribution of the eurasian red squirrel, one learns that the species evolved in a world void of other tree squirrels and thus was not subject to selective pressures that made it a ‘tuff guy’ ready to face competitors with similar tree-dwelling and seed-eating habits. Very different from the situ- ation faced by its cousins in North-America, where often up to three tree- squirrel species are sympatric in parts of the continent. hence, the red squirrel was the only arboreal squirrel species in europe until man decided to ‘fool’ around with the precarious interdependencies that had evolved between squirrels and trees by introducing other squirrel species from far away continents. the release of ‘alien’ eastern gray squir- rels, whose home is central and east usA and south-east canada, into the British isles and italy has reduced our red squirrel from an overall presence in all suitable forests, woodlands and even parks, to a threatened species in most of the British isles and in a large part of northern italy. moreover, the italian populations of invasive gray squirrels are bound to spread into neighbouring countries in the next 20–40 years (or sooner, should people continue to irresponsibly release bought pet squirrels), if no steps are taken to stop them from advancing towards France and switzerland. this is not a natural process but caused by human intervention and we are responsi- ble for the extinction of our red squirrels in areas colonised by the intro- duced congener. We thus have the responsibility to do all we can to save this wonderful animal, so well-adapted to our forest ecosystems but not to the presence of a heavier, faster-growing and introduced competitor, from wide-scale extinction in europe. let’s hope that this book will reach readers throughout europe and con- vince them of the uniqueness and beauty of our red squirrel and of our duty to do all we can to save it, so that also the future generations, while having their sunday walk, can remain surprised and spellbound by a red squirrel jumping around and hiding its precious hazelnut. Dr luc Wauters Varese, italy Leseprobe © Westarp Wissenschaften 2012 Introduction every book has its history and the history of our book began in 1956. in that year the ‘Neue Brehm-Bücherei’ published a monograph on the red squir- rel. it encompassed 56 pages, 51 images and 28 literature sources and was written by Dr Wolfgang gewalt (1928–2007), a well known zoologist and director of the Duisburg Zoo. this was followed by two landmark publica- tions on squirrels in 1987 by Dr John gurnell and Dr Jessica holm respec- tively. since then there has been a huge and world-wide interest in squir- rels, with research into their ecology, behaviour, conservation and compe- tition, providing a wealth of new information on these fascinating forest animals. in particular, research on red squirrels in Belgium, the uK and italy applying new methodologies such as radio-tracking, genetics, com- puter modelling and geographic information systems have revolutionised our understanding of this species and its role in forest ecosystems. April 2011 therefore saw the publication of a revised red squirrel monograph in germany (Westarp Verlag), which thanks to the interest of the publishers in an english language edition will now be accessible to english-speaking readers. this seemed an obvious way to go, given that one of the authors has spent the last 20 years living and ‘chasing’ squirrels in the British isles. the book tries to give a comprehensive overview of our current knowl- edge and published scientific research on red squirrels and includes, for example, details and images of red squirrel anatomy and behaviour that have never been published before. Advances over the last 25 years in our understanding of red squirrels were especially made with respect to their space use, activity patterns, population dynamics, dispersal behaviour and the complex ecological interactions and interdependencies between squir- rels and the plant and animal species community that comprise forest eco- systems. it is not possible to write a book about the eurasian red squirrel without mentioning the eastern gray squirrel, which has been released in the uK, ireland and italy, and its devastating impact on native red squirrel popu- lations. 125 years after its first release in the uK, mainland england and Wales are almost completely ‘grey’. red-gray squirrel interactions and how eastern gray squirrels compete with and replace red squirrels have Leseprobe © Westarp Wissenschaften 2012 10 introduction therefore been the focus of research in the uK and ireland, highlighting the initially undetected but critical role of wildlife diseases in competition and decline. the book attempts to explain the range of factors that contribute to red squirrel populations going extinct and stresses the dangers posed by expanding gray squirrel populations in northern italy to red squirrel populations in neighbouring switzerland, France, and central and south- ern europe beyond. the problem is made worse by continuing and irre- sponsible releases of bought North American or Asian squirrels in parks or woodlands which in many cases lead to the establishment of new popula- tions and range increases of these alien squirrels. Both the eastern gray squirrel or the Pallas squirrel, which have been introduced to a number of european countries, are linked to extensive tree damage as well as dam- age to agricultural crops and impacts on native wildlife. they illustrate the complex issues posed by non-native species introductions and the need for management decisions that are based on conservation and economic, legal, and ethical considerations.