Provided by the author(s) and NUI Galway in accordance with publisher policies. Please cite the published version when available. Title Post-release Monitoring of Two Translocated Red Squirrel (Sciurus vulgaris L.) Populations Author(s) Waters, Catherine Publication Date 2012-10-24 Item record http://hdl.handle.net/10379/3041 Downloaded 2021-09-23T15:16:11Z Some rights reserved. For more information, please see the item record link above. Post-release Monitoring of Two Translocated Red Squirrel (Sciurus vulgaris L.) Populations A thesis submitted for the degree of Ph.D. to the National University of Ireland, Galway by: Catherine Waters Supervisor Dr. Colin Lawton Head of Department Dr. Grace McCormack School of Natural Sciences, National University of Ireland, Galway October 2012 Table of Contents Pages Abstract vi Acknowledgements viii List of Figures x List of Tables xiii List of Plates xvi 1 General Introduction 1.1 Squirrel taxonomy 1 1.2 Red squirrel biology 5 1.3 History of squirrels in Ireland 7 1.4 The distribution of squirrels in Ireland 7 1.5 Competition 9 1.6 Legislation and conservation 11 1.7 Translocation 12 1.8 Post-release monitoring 13 1.9 Project Aims 14 2 Translocation and early post-release settlement of a red squirrel population in the west of Ireland 2.1 Introduction 15 2.1.1 Considerations for translocation 15 2.1.2 History of red squirrel translocation in Europe 16 2.1.3 Background to Belleek Forest Park translocation 18 2.1.4 Aims and Objectives 20 2.2 Materials and Methods 21 2.2.1 Target site 21 2.2.2 Translocation procedure 23 2.2.3 Radio telemetry 26 2.2.4 Live trapping 27 i 2.2.5 Work Schedule 32 2.3 Results 33 2.3.1 Translocation 33 2.3.2 Radio telemetry 34 2.3.3 Initial live trapping sessions 40 2.4 Discussion 43 2.4.1 Translocation of red squirrels to Belleek Forest Park 43 2.4.2 Settlement behaviour and home ranges 47 2.4.3 Public involvement and the use of supplementary feeding 50 2.5 Summary and Conclusion 51 3 Medium-term post-release monitoring of a population of red squirrels 3.1 Introduction 53 3.1.1 Techniques for monitoring wildlife 53 3.1.2 Techniques for monitoring squirrel populations 54 3.1.3 Post-release monitoring techniques of translocated squirrel populations 56 3.1.4 Background to two post-release monitoring studies in Ireland 59 3.1.5 Aims and Objectives 61 3.2 Materials and Methods 62 3.2.1 Study site 62 3.2.2 Direct field techniques 64 3.2.3 Indirect field techniques 70 3.2.4 Work schedule 74 3.3 Results (Derryclare wood) 76 3.3.1 Population estimation 76 3.3.2 Recruitment 79 3.3.3 Habitat use by radio collared squirrels 80 3.3.4 Individual fitness and breeding status 81 3.3.5 Red squirrel dispersal through the woodland 86 3.3.6 Seed crop analysis 91 ii 3.3 Results (Belleek Forest Park) 95 3.3.7 Population estimates and density 95 3.3.8 Recruitment 97 3.3.9 Individual fitness and breeding status 98 3.3.10 Dispersal of red squirrels from Belleek Forest Park 105 3.3.11 Habitat quality and seed crop 106 3.4 Discussion 108 3.4.1 Red squirrel population abundance 108 3.4.2 Population demographics 110 3.4.3 Red squirrel dispersal 113 3.4.4 Habitat quality and seed crop analysis 115 3.5 Summary and Conclusion 119 4. The Impact of Habitat Loss on Red Squirrel Populations 4.1 Introduction 121 4.1.1 Planned and unplanned events and forestry 121 4.1.2 Forest management and policy 123 4.1.3 Background to habitat loss at Derryclare wood 125 4.1.4 Aims and Objectives 127 4.2 Materials and Methods 128 4.2.1 Study site 128 4.2.2 Live trapping 134 4.2.3 Carrying capacity 136 4.2.4 Habitat quality 136 4.2.5 Work and event schedule 137 4.3 Results 138 4.3.1 Population and density estimates 138 4.3.2 Recruitment 139 4.3.3 Individual fitness 140 4.3.4 Carrying capacity 142 iii 4.3.5 Habitat quality 147 4.4 Discussion 149 4.4.1 Impact of clear-felling on squirrel populations 149 4.4.2 Impact of forest fire on squirrel populations 151 4.4.3 Derryclare wood as a sustainable habitat 152 4.4.4 Mapping the future of Derryclare wood for the red squirrel population 153 4.5 Summary and Conclusion 155 5 The Potential Threat of Grey Squirrel Infiltration into Belleek Forest Park 5.1 Introduction 157 5.1.1 Habitat fragmentation and its effects on squirrel populations 157 5.1.2 Squirrel habitat in the west of Ireland 158 5.1.3 Grey squirrel management and control methods 159 5.1.4 Modelling the spread of an invasive species 162 5.1.5 Background to this section of the study 162 5.1.6 Aims and Objectives 163 5.2 Materials and Methods 164 5.2.1 Study area 164 5.2.2 Survey work 166 5.2.3 Squirrel habitat suitability 166 5.2.4 Least Cost Pathway model 168 5.3 Results 170 5.3.1 Survey responses 170 5.3.2 Land-use in the western region of Ireland 172 5.3.3 Least Cost Pathway analysis 173 5.4 Discussion 177 5.4.1 Survey results 177 5.4.2 Land-use and its impact on squirrel dispersal 178 5.4.3 Least Cost Pathways 180 5.4.4 Implementation of grey squirrel monitoring and control 182 iv 5.5 Summary and Conclusion 184 6 General Discussion 6.1 Overview of red squirrel populations at Belleek Forest Park and Derryclare wood 186 6.2 Post-translocation management: What role does it play? 188 6.3 Translocation and its role in the conservation of the red squirrel in Ireland 191 6.4 Translocation and its role as a conservation tool for animal populations in general 193 6.5 Conclusions 195 7 References 196 8 Appendices 226 v Abstract The red squirrel (Sciurus vulgaris) has suffered a 20% decline in its range in Ireland since the introduction of the grey squirrel (Sciurus carolinensis) mainly through competition. Translocation (the intentional movement of a living organism from one area to another) of red squirrels was conducted in Derryclare wood, Connemara between July and October 2005. This project has investigated the fate of this red squirrel population through post-release monitoring techniques. A second translocation to Belleek Forest Park, Co Mayo was also conducted and the establishment and subsequent well-being of this population was also investigated. The second translocation of red squirrels to Belleek was conducted in a three phase programme in 2007 and 2008. Fifteen individuals were translocated in what was designed as a soft release procedure, although there were some problems of squirrels escaping from the enclosure during the second and third phase of the translocation. A fourth phase of translocation was deemed unnecessary as the population began to breed and recruit new individuals. Initial success was recorded using short-term monitoring. Settlement patterns investigated by radio telemetry displayed a priority for locating food initially after release; individuals tracked were found to include the release enclosure and supplementary feeders within home ranges. Not all squirrels established core areas initially using their home range uniformly. However, during a second tracking session, conducted 18 months later, a pattern more in keeping with that of established squirrel populations was shown; individuals were utilising other areas of the wood including parts without supplementary feeders and all had preferred core areas within their home range. Post-release monitoring in Derryclare was mainly conducted through live trapping, between June 2008 and March 2011. It was found that the population had dispersed further into the woodland since work had finished there in 2007 and were utilising new areas. Six of the originally translocated stock were captured near to or within the Nature Reserve in which the release enclosures had been based. Both red squirrel populations at Belleek Forest Park and Derryclare wood were monitored to investigate establishment of each population and their demographics in the medium-term. Comparison between the populations in each wood showed that spread of the red squirrels was influenced by difference in habitat type. The red squirrel population at Belleek were found to have inhabited all available habitat and then increased in density, whereas, the population at Derryclare were found to have spread through the woodland as their density increased. Recruitment of individuals was high at both sites, these new squirrels were the progeny of translocated stock as both areas were isolated from the possible immigration of other red squirrels. Over the course of the study both populations showed an increase in abundance year on year. Habitat quality was also monitored at both sites. vi The future success of both translocations was considered and the potential threats to the populations analysed, in order to investigate the long-term prospects of both populations. At Derryclare wood, the potential impact of habitat loss was investigated. This was achieved by examining the changing squirrel carrying capacity of the woodland due to planned clear-felling procedures. It was found that if felling was conducted as planned by land-owners, then a sufficient sustainable habitat would be available for the red squirrel population in the future. However, in April 2011, 150 hectares of forest were impacted by a forest fire.