HABITAT MODELLING AND THE ECOLOGY OF THE MARSH TIT (POECILE PALUSTRIS) RICHARD K BROUGHTON A thesis submitted in partial fulfilment of the requirements of Bournemouth University for the degree of Doctor of Philosophy August 2012 Bournemouth University in collaboration with the Centre for Ecology & Hydrology This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and due acknowledgement must always be made of the use of any material contained in, or derived from, this thesis. 2 ABSTRACT Richard K Broughton Habitat modelling and the ecology of the Marsh Tit (Poecile palustris) Among British birds, a number of woodland specialists have undergone a serious population decline in recent decades, for reasons that are poorly understood. The Marsh Tit is one such species, experiencing a 71% decline in abundance between 1967 and 2009, and a 17% range contraction between 1968 and 1991. The factors driving this decline are uncertain, but hypotheses include a reduction in breeding success and annual survival, increased inter-specific competition, and deteriorating habitat quality. Despite recent work investigating some of these elements, knowledge of the Marsh Tit’s behaviour, landscape ecology and habitat selection remains incomplete, limiting the understanding of the species’ decline. This thesis provides additional key information on the ecology of the Marsh Tit with which to test and review leading hypotheses for the species’ decline. Using novel analytical methods, comprehensive high-resolution models of woodland habitat derived from airborne remote sensing were combined with extensive datasets of Marsh Tit territory and nest-site locations to describe habitat selection in unprecedented detail. Further fieldwork established the causes and frequency of breeding failure at the local population scale, and dispersal distances and success were quantified. Information from these studies was used to inform national-scale spatial analyses of habitat distribution in relation to the pattern of range contraction for the Marsh Tit and two other woodland bird species. The combined results indicate that Marsh Tits require extensive areas of mature woodland in order to accommodate large territories and short dispersal distances, with greatest selection for a woodland structure encompassing a tall, near-closed tree canopy and extensive understorey. The evidence suggests that nest-site competition, nest predation or deteriorating habitat quality have not driven the population decline. However, reduced connectivity between woodlands in the landscape, possibly due to hedgerow loss, may have interacted with increased mortality to precipitate population declines and local extinctions where habitat fragmentation was relatively high. The potential causes of increased mortality are discussed, along with priority areas for future research and the wider possible applications of remote sensing techniques in the field of woodland bird research. 3 LIST OF CONTENTS TITLE PAGE 1 COPYRIGHT STATEMENT 2 ABSTRACT 3 LIST OF CONTENTS 4 LIST OF FIGURES 6 LIST OF TABLES 6 PREFACE AND ACKNOWLEDGEMENTS 7 AUTHOR’S DECLARATION 8 1 INTRODUCTION 9 1.1 Introduction to the thesis 9 1.1.1 The global biodiversity crisis 9 1.1.2 Bird biodiversity indicators in the UK 10 1.1.3 Declines of woodland birds 11 1.2 The Marsh Tit 12 1.2.1 Classification and history of the Marsh Tit 12 1.2.2 Field studies of the Marsh Tit 1937-2002 12 1.2.3 Historical and current population status in Britain 15 1.2.4 Proposed causes of the Marsh Tit’s decline 15 1.2.5 Contemporary work on the Marsh Tit 16 1.3 Trends in the woodlands of England and Wales in the latter half of the 20th Century 17 1.3.1 Large-scale trends in broadleaved woodland habitat 17 1.3.2 Changes in woodland vegetation structure and composition 18 1.3.3 Impacts of deer 19 1.3.4 Trends in woodland fragmentation and isolation 20 1.3.5 Potential implications of habitat change for the Marsh Tit 21 1.4 Characterising woodland habitat 22 1.4.1 Field surveys 22 1.4.2 Remote sensing methods 23 1.5 Origin and aims of the thesis 24 1.5.1 Origins of the research 24 1.5.2 Outline and specific objectives of the thesis 24 2 STUDY AREA AND DATA COLLECTION METHODS 27 4 2.1 Study area 27 2.2 Marsh Tit data collection 28 2.2.1 Core and peripheral study areas 28 2.2.2 Methods of capture and marking 30 2.2.3 Recording of movements and nest-sites 30 2.3 Vegetation data from field survey 32 2.4 Vegetation data from remote sensing 32 2.4.1 Woodland canopy height models 32 2.4.2 Woodland understorey height model 33 2.4.3 Tree species digital map 33 3 MARSH TIT TERRITORIES AND HABITAT SELECTION 34 3.1 Paper I: Marsh Tit Poecile palustris territories in a British broadleaved Wood 36 3.2 Paper II: Describing habitat occupation by woodland birds using territory mapping and remote sensing data: an example using the Marsh Tit (Poecile palustris) 45 4 FACTORS DETERMINING NEST-SITE SELECTION 69 4.1 Paper III: Patterns of nest placement in a population of Marsh Tits 71 5 NEST-SITES AND BREEDING SUCCESS 95 5.1 Paper IV: Nest-sites, breeding failure, and causes of non-breeding in a population of British Marsh Tits 97 6 PATTERNS OF DISPERSAL AND RANGING BEHAVIOUR 106 6.1 Paper V: Dispersal, ranging and settling behaviour of Marsh Tits in a fragmented landscape in lowland England 108 7 PATTERNS OF DISTRIBUTION CHANGE AND HABITAT COVERAGE 122 7.1 Paper VI: Relationships between patterns of habitat cover and the historical distribution of the Marsh Tit, Willow Tit and Lesser Spotted Woodpecker in Britain 124 8 DISCUSSION 144 8.1 Marsh Tit territories and habitat selection 144 8.2 The impact of deer and management on Marsh Tit habitat 145 5 8.3 Characterising woodland habitat for Marsh Tits and other species 147 8.4 Marsh Tit breeding success 148 8.5 Dispersal and settling success 149 8.6 Landscape ecology of the Marsh Tit 150 8.7 Mortality 151 8.7.1 Predation 151 8.7.2 Inter-specific competition 152 9 CONCLUSIONS 153 9.1 Causes of the decline of the British Marsh Tit 153 9.2 Management recommendations for Marsh Tit conservation 154 REFERENCES 156 ABBREVIATIONS 170 APPENDIX 1A: Separation of Willow Tit and Marsh Tit in Britain: a review 171 APPENDIX 1B: Ageing and sexing Marsh Tits using wing-length and moult 184 APPENDIX 2: CERTIFICATIONS OF AUTHOR’S CONTRIBUTION 191 LIST OF FIGURES Figure 1 Map of the study area 28 Figure 2 Movements of Marsh Tits between woodlands 107 LIST OF TABLES Table 1 Trends in the cover of canopy and understorey vegetation within woodlands between the 1980s and 2004 19 Table 2 Trends in the distribution of deer between 1972 and 2007 21 Table 3 Names and characteristics of woods in the study area 29 6 PREFACE AND ACKNOWLEDGEMENTS This study contained within this thesis began with fieldwork initiated at Monks Wood National Nature Reserve (NNR) in the 1990s by Dr Shelley Hinsley and Paul Bellamy, which involved the colour-ringing of Marsh Tits to determine the population size. In 2002 I was offered the opportunity to develop the project into a systematic study of the spatial ecology and behaviour of the Marsh Tit, which was and remains topical due to the national decline in the species’ abundance. The availability of a large study population and extensive study area meant that high-quality investigations of the Marsh Tit’s population and landscape ecology were possible. Furthermore, spatial habitat data derived from airborne remote sensing provided some of the most comprehensive woodland habitat datasets anywhere in the world. The opportunity to combine this with spatial data of the movements, territory extent and nest-site locations of Marsh Tits enabled the development of novel analyses with which to describe bird-habitat relationships in unprecedented detail. As such, there was great potential for a rewarding project that could inform the understanding of the Marsh Tit’s decline, but also contribute to wider woodland bird research and conservation. I am deeply indebted to my supervisory team of Dr Shelley Hinsley of the Centre for Ecology & Hydrology (CEH) and Dr Ross Hill of Bournemouth University (BU) for unwavering support and encouragement during the course of this work. I also thank CEH for support throughout the project and part-funding this thesis submission, and also BU for accepting me as a Visiting Research Fellow to enable this submission. I am very grateful to Dr Stephen Freeman and Dr Peter Rothery, respectively current and former colleagues at CEH, for statistical advice. Dr Ross Hill and colleagues processed and supplied the remote sensing data while at the Earth Observation Section at CEH Monks Wood. I also thank the British Trust for Ornithology for supplying national datasets of bird distribution. A number of students and colleagues contributed to fieldwork data collection during the study, and I thank Dr Jane Carpenter, Dr Daria Dadam, Deborah Marchant, and particularly Paul Bellamy and Dr Shelley Hinsley. I am also indebted to the landowners and managers for access to the woodland study sites, and particularly to Natural England for access to Monks Wood NNR. I am also especially grateful to Geoff Leach and Sarah Caesar for invaluable logistical support during fieldwork. Finally, I wish to thank the numerous reviewers and editors of the published and accepted journal papers contained within this thesis, for constructive criticism of the work. 7 AUTHOR’S DECLARATION As a submission for a PhD by publications, the published papers presented in this thesis have previously appeared in scientific journals as indicated.