Habitat Use, Haul-Out Behaviour & Site
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Habitat Use, Haul-Out Behaviour & Site Fidelity of Grey Seals (Halichoerus grypus) along the Ceredigion Marine Heritage Coast, Wales Kate Michelle Lewis 2006 School of Biological Sciences, University of Wales, Bangor Deiniol Road, Bangor, Gwynedd LL57 2UW In association with: A dissertation presented in partial fulfillment of the requirements for the degree of Master of Science in Marine Mammal Science of the University of Wales Habitat Use, Haul-Out Behaviour & Site Fidelity of Grey Seals (H. grypus) along the Ceredigion Marine Heritage Coast, Wales My dearest little sister Pippa You are a brave & beautiful rose…stay strong. Kate Michelle Lewis, 2006 ii Habitat Use, Haul-Out Behaviour & Site Fidelity of Grey Seals (H. grypus) along the Ceredigion Marine Heritage Coast, Wales Abstract Grey seals were sighted from visitor passenger boat (VPB) trips within all ten zones of the Ceredigion Marine Heritage Coast between New Quay and Ynys Lochtyn in 2004 and 2005, demonstrating their presence along the coastline within Cardigan Bay Special Area of Conservation (SAC). Environmental variables, collected via VPB trips and direct observation from Bird’s Rock, a designated Site of Special Scientific Interest, were analysed using univariate and multivariate methods to investigate whether a particular factor influenced grey seal haul-out behaviour. Although tide, time of day, adjusted air temperature and disturbance primarily influenced haul-out behaviour at Bird’s Rock, it is evident a complex dynamic of intrinsic and extrinsic factors interact to determine haul-out behaviour. Potential human-induced disturbance was investigated via logging grey seal-vessel interactions observed during direct observation surveys at Bird’s Rock. Vessel traffic appeared not to induce short-term behavioural responses in the majority of seals present, suggesting vessels abiding the Ceredigion Marine Conservation Code of Conduct did not disturb seals in the short-term. Although infrequent, research vessels abiding and canoes violating the Code of Conduct resulted in seals permanently modifying their behaviour and/or escaping Bird’s Rock. Given long-term effects of vessel disturbance are unknown, this study supports requirements of further study. Photo-identification of grey seals encountered along the Ceredigion coastline exhibited a degree of intra-seasonal and inter- annual site fidelity, particularly to Bird’s Rock and Cwmtydu, a pupping beach. 52% of individuals were resighted at least twice within the initial season photographed. One bull (ID: 015) was encountered in three successive years (2003-2005) whereas a female (ID: 007) known to have pupped at Cwmtydu in 2003 was resighted there in August 2005. Furthermore, grey seals at Bird’s Rock exhibited preference for specific haul-out rocks at Bird’s Rock. Finally, direct observation revealed that education of tourists remains paramount in maintaining the protection of Grey Seals along the Ceredigion Marine Heritage Coast. The continuation of a precautionary approach to management within this area is required. Kate Michelle Lewis, 2006 iii Habitat Use, Haul-Out Behaviour & Site Fidelity of Grey Seals (H. grypus) along the Ceredigion Marine Heritage Coast, Wales Table of Contents Abstract.....................................................................................................................................................iii Table of Contents................................................................................................................................... iv List of Figures......................................................................................................................................... vi List of Tables ...........................................................................................................................................ix List of Appendices ...................................................................................................................................x List of Accompanying Material..............................................................................................................x Acknowledgements.................................................................................................................................xi Declaration............................................................................................................................................. xii Glossary ................................................................................................................................................. xiii 1.0 Introduction........................................................................................................................................1 1.1 Cardigan Bay ..................................................................................................................................1 1.1.1 Bathymetry..............................................................................................................................1 1.1.2 Sedimentology........................................................................................................................1 1.1.3 Sea-Surface Temperature & Salinity ...................................................................................2 1.1.4 Water Masses & Circulation.................................................................................................2 1.2 Bird’s Rock.....................................................................................................................................4 1.3 Cwmtydu ........................................................................................................................................4 1.4 Ynys Lochtyn.................................................................................................................................4 2.0 Local Conservation & Management ...............................................................................................5 2.1 Ceredigion Marine Heritage Coast (CMHC).............................................................................5 2.2 Special Area of Conservation (SAC) ..........................................................................................5 3.0 Protection of Grey Seals...................................................................................................................6 4.0 Grey Seal Distribution, Population Status & Life History ..........................................................6 4.1 Worldwide ......................................................................................................................................6 4.2 United Kingdom............................................................................................................................7 4.3 Morphology....................................................................................................................................7 4.4 Diet..................................................................................................................................................9 4.5. Life History ...................................................................................................................................9 4.5.1. Annual & Temporary Haul-Out.........................................................................................9 4.5.2 Breeding ............................................................................................................................... 10 5.0 Introduction to Photo-identification ........................................................................................... 12 6.0 Aims and Objectives ...................................................................................................................... 14 7.0 Methodology.................................................................................................................................... 15 7.1. One-/Two-Hour Visitor Passenger Boat (VPB) Trips ....................................................... 15 7.2 Direct Observation at Bird’s Rock .......................................................................................... 15 7.2.1 Environmental & Behavioural Observations ................................................................. 17 7.2.2. Grey Seal-Vessel Interactions .......................................................................................... 17 7.3. Opportunistic Photo-Identification........................................................................................ 20 8.0 Results............................................................................................................................................... 21 8.1 One-/Two-Hour Visitor Passenger Boat (VPB) Trips Sightings Data.............................. 21 8.1.1. Habitat Use along the Ceredigion Marine Heritage Coast (CMHC).......................... 21 8.1.2. Monthly Variation ............................................................................................................. 24 8.1.3. Daily Variation ................................................................................................................... 25 8.1.4. Hours from Low Tide....................................................................................................... 25 8.1.5. Tidal Phase.......................................................................................................................... 28 8.2. Direct Observation