Disturbance Studies on Swansea Bay and the Burry Inlet in Relation to Bird Populations
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BTO Research Report No. 107 Disturbance studies on Swansea Bay and the Burry Inlet in relation to bird populations by J. Evans & N.A. Clark A report by the British Trust for Ornithology under contract to the Countryside Council for Wales © British Trust for Ornithology The National Centre for Ornithology, The Nunnery, Thetford, Norfolk. IP24 2PU BTO Research Report No. 107 August 1993 LIST OF CONTENTS Page No List of Figures..................................................................................................................................3 Executive Summary.......................................................................................................................9 1. General Introduction .......................................................................................................11 2. Bait-digging Studies........................................................................................................ 13 2.1 Introduction..........................................................................................................13 2.2 Methods .................................................................................................................14 2.3 Analysis..................................................................................................................14 2.4Results ..........................................................................................................................15 2.5 Conclusions...........................................................................................................17 3.Beach Cleaning Studies............................................................................................................19 3.1 Introduction..........................................................................................................19 3.2 Methods .................................................................................................................19 3.3 Results....................................................................................................................19 3.4 Conclusions...........................................................................................................20 4. Cockling Access ...............................................................................................................21 4.1 Introduction..........................................................................................................21 4.2 Methods .................................................................................................................21 4.3 Results....................................................................................................................22 4.4Conclusions .................................................................................................................25 Acknowledgements .....................................................................................................................27 References.......................................................................................................................................29 Figures ............................................................................................................................................31 BTO Research Report No. 107 August 1993 - 1 - BTO Research Report No. 107 August 1993 - 2 - LIST OF FIGURES Figure 2.1The study sites on western Swansea Bay (Mumbles, Blackpill and Marina) with their constituent count areas.......................................31 Figure 2.2The study sites on eastern Swansea Bay (Crymlyn) with its constituent count areas........................................................................................................ 32 Figure 2.3The Blackpill study site with its 11 count areas............................................. 33 Figure 2.4The average number of feeding Oystercatchers recorded on each count area within the Blackpill study site in the period between three hours before and three hours after low tide during February 1993................................................................................. 34 Figure 2.5The average number of Oystercatchers present on the upper areas and the average number present on the lower areas within the Blackpill study site throughout the core usage period (between three hours before and three hours after low tide) in February 1993 ................................................................................ 35 Figure 2.6The average number of Oystercatchers present on the upper areas and the average number present on the lower areas throughout the tidal cycle within the Blackpill study site during the 1991-92 winter.......................................................................... 36 Figure 2.7The average number of feeding Ringed Plover recorded on each count area within the Blackpill study site in the period between three hours before and three hours after low tide during February 1993................................................................................. 37 Figure 2.8The average number of Ringed Plover present on the upper areas and the average number present on the lower areas within the Blackpill study site throughout the core usage period (between three hours before and three hours after low tide) in February 1993 ................................................................................ 38 Figure 2.9The average number of Ringed Plover present on the upper areas and the average number present on the lower areas throughout the tidal cycle within the Blackpill study site during the 1991-92 winter.......................................................................... 39 Figure 2.10The average number of feeding Grey Plover recorded on each count area within the Blackpill study site in the period between three hours before and three hours after low tide during February 1993................................................................................. 40 BTO Research Report No. 107 August 1993 - 3 - Figure 2.11The average number of Grey Plover present on the upper areas and the average number present on the lower areas within the Blackpill study site throughout the core usage period (between three hours before and three hours after low tide) in February 1993 .................................................................................41 Figure 2.12The average number of Grey Plover present on the upper areas and the average number present on the lower areas throughout the tidal cycle within the Blackpill study site during the 1991-92 winter.......................................................................... 42 Figure 2.13The average number of feeding Sanderling recorded on each count area within the Blackpill study site in the period between three hours before and three hours after low tide during February 1993................................................................................. 43 Figure 2.14The average number of Sanderling present on the upper areas and the average number present on the lower areas within the Blackpill study site throughout the core usage period (between three hours before and three hours after low tide) in February 1993 ......................................................................................... 44 Figure 2.15The average number of Sanderling present on the upper areas and the average number present on the lower areas throughout the tidal cycle within the Blackpill study site during the 1991-92 winter.......................................................................... 45 Figure 2.16The average number of feeding Dunlin recorded on each count area within the Blackpill study site in the period between three hours before and three hours after low tide during February 1993................................................................................. 46 Figure 2.17The average number of Dunlin present on the upper areas and the average number present on the lower areas within the Blackpill study site throughout the core usage period (between three hours before and three hours after low tide) in February 1993 ......................................................................................... 47 Figure 2.18The average number of Dunlin present on the upper areas and the average number present on the lower areas throughout the tidal cycle within the Blackpill study site during the 1991-92 winter.......................................................................... 48 Figure 2.19The average number of feeding Bar-tailed Godwit recorded on each count area within the Blackpill study site in the period between three hours before and three hours after low tide during February 1993 ......................................................................... 49 BTO Research Report No. 107 August 1993 - 4 - Figure 2.20The average number of Bar-tailed Godwit present on the upper areas and the average number present on the lower areas within the Blackpill study site throughout the core usage period (between three hours before and three hours after low tide) in February 1993................................................................ 50 Figure 2.21The average number of Bar-tailed Godwit present on the upper areas and the average number present on the lower areas throughout the tidal cycle within the Blackpill study site during the 1991-92 winter....................................................................51 Figure 2.22The average number of feeding Curlew recorded on each count area within