The influence of environmental variation on individual foraging and habitat selection behaviour of the European nightjar Lucy Jayne Mitchell PhD University of York Environment and Geography July 2019 2 Abstract Animals experience a variety of environmental stressors, for example climate and habitat change. These changes can alter the distribution and population dynamics of species indirectly through disruption of behavioural processes, including foraging. Collecting behavioural data, such as foraging tracks, from multiple individuals can help to identify how response to habitat change, is driven by factors such as resource distribution, intra-specific competition and intrinsic factors such as sex and age. This thesis combined behavioural and dietary information collected from individual European nightjars Caprimulgus europaeus, to analyse variation in behaviour amongst the population, in response to habitat change and the consequences this might have in terms of future change and for beneficial management. This population of nightjars showed significant individual variation in home range size and habitat selection therein. Home ranges sizes increased by 1% and decreased by 9% in wetland and newly cleared habitat respectively. This indicated that although birds possess individual preferences for specific habitat types, there are foraging constraints that affect multiple individuals. Foraging behaviour changed most strongly in relation to habitat type, NDVI and more weakly in relation to the lunar cycle and temperature. Time spent foraging increased in cleared habitat (β: 0.03, R2 0.08, p: 0.07), which became more available during the study. Males spent 33% of their time foraging compared to females which spent only 18.6% of their time foraging, representing differing breeding roles. However, strong methodological influence was clear, whereby an increase in the fix interval from 3 to 5 minutes caused a 39% increase in step length, unaccounted for by year or habitat change. Individual diet composition differed and changed between years, in response to prey availability, however common species occurred in 40-50% of samples. Overall nightjars selected for larger moths compared to local availability. Collectively, my results and demonstrated flexibility at the population level and the potential to respond positively to habitat. As a species specialising in a spatially- and temporally- varying prey resource, maintenance of complex habitat mosaics that encourage a wide diversity of moth and other flying insect species, along with the diversity of habitat types to encourage breeding and survival of all individuals. 3 Table of Contents Table of Contents ............................................................................................................. 4 List of Tables .................................................................................................................... 9 List of Figures ................................................................................................................. 11 Acknowledgements ........................................................................................................ 15 Declaration ..................................................................................................................... 16 Publications .................................................................................................................... 16 Funding ................................................................................................................... 16 Chapter 1: Introduction ................................................................................................... 18 1.1 Species decline ..................................................................................................... 18 1.2 Conservation measures ........................................................................................ 20 1.3 Individual and population-level responses to environmental change ..................... 21 1.4. Behavioural variation ............................................................................................ 26 1.5. Incorporating individual behaviour into habitat management ................................ 29 1.6 New technologies for applied ecology and conservation ....................................... 31 1.6.1. Tracking animals for behavioural studies ....................................................... 31 1.6.2. Device effects ................................................................................................ 32 1.6.3. Diet metabarcoding ........................................................................................ 33 1.7 The European nightjar ........................................................................................... 36 1.7.1. Population status ........................................................................................... 36 1.7.2. Previous studies of nightjar behaviour ........................................................... 41 1.7.3. Nightjar diet ................................................................................................... 44 1.7.4. Study site: Humberhead Peatlands National Nature Reserve ........................ 46 1.7.5. LIFE+ Restoration Project .............................................................................. 49 1.7.6. Aims and objectives ....................................................................................... 51 1.8. Thesis Outline ...................................................................................................... 56 Chapter 2: The trade-off between fix rate and tracking duration on estimates of home range size and habitat selection for small vertebrates .................................................... 58 2.1 Abstract ................................................................................................................. 58 2.2. Introduction .......................................................................................................... 59 4 2.2.1 Study scenario ................................................................................................ 63 2.3. Materials and methods ..................................................................................... 64 2.3.1. Habitat Mapping ............................................................................................. 65 2.3.2. GPS data processing ..................................................................................... 65 2.3.3. Autocorrelation assessment ........................................................................... 67 2.3.4. Modelling ....................................................................................................... 68 2.4. Results ............................................................................................................. 71 2.4.1. Home range information ............................................................................ 71 2.4.2. Modelling results ........................................................................................ 72 2.4.3. Habitat Selection ....................................................................................... 76 2.4.4. Direct data comparison .............................................................................. 78 2.5. Discussion ........................................................................................................ 80 2.5.1. How sensitive are estimates of home range size and shape to changes in fix rate and tracking duration? ...................................................................................... 80 2.5.2. How sensitive are estimates of habitat selection to any changes in the tracking parameters and method of home range estimation and are the conclusions equivalent across all rates, durations and methods? ................................................ 82 2.6. Conclusions ...................................................................................................... 84 Chapter 3: Multi-year tracking reveals high individual variability in habitat selection and functional habitat relationships in European nightjars ..................................................... 85 3.1. Abstract ................................................................................................................ 85 3.2. Introduction .......................................................................................................... 86 3.2.1. Study species ................................................................................................ 88 3.2.2. Study aims ..................................................................................................... 88 3.3. Materials and methods ......................................................................................... 90 3.3.1. GPS data collection ....................................................................................... 90 3.3.2. Habitat mapping ............................................................................................. 90 3.3.3. Home range models ....................................................................................... 91 3.3.4. Habitat selection ............................................................................................ 91 3.3.5. Changes in home range size and habitat selection ratios............................... 92 3.4. Results ................................................................................................................