Distribution and Population Dynamics of the Kerry Slug, Geomalacus Maculosus (Arionidae)
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Distribution and population dynamics of the Kerry Slug, Geomalacus maculosus (Arionidae) Irish Wildlife Manual No. 54 Distribution and population dynamics of the Kerry Slug, Geomalacus maculosus (Arionidae) Rory Mc Donnell & Mike Gormally Applied Ecology Unit, Centre for Environmental Science, School of Natural Sciences, NUI Galway, Ireland. Citation: Mc Donnell, R.J. and Gormally, M.J. (2011). Distribution and population dynamics of the Kerry Slug, Geomalacus maculosus (Arionidae). Irish Wildlife Manual s, No. 54. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland. Cover photo: Geomalacus maculosus © Rory Mc Donnell The NPWS Project Officer for this report was: Dr Brian Nelson; [email protected] Irish Wildlife Manuals Series Editor: F. Marnell & N. Kingston © National Parks and Wildlife Service 2011 ISSN 1393 – 6670 Distribution and population dynamics of Geomalacus maculosus ____________________________________________________ CONTENTS EXECUTIVE SUMMARY ................................................................................................................................1 ACKNOWLEDGEMENTS ...............................................................................................................................2 1. INTRODUCTION ......................................................................................................................................3 Background information on Geomalacus maculosus .......................................................................3 Research Objectives.............................................................................................................................6 2. SURVEY FOR GEOMALACUS MACULOSUS ..................................................................................................7 Rationale................................................................................................................................................7 Materials and methods ........................................................................................................................7 Results and discussion.........................................................................................................................8 3. IDENTIFICATION OF A LIVE TRAPPING METHOD FOR GEOMALACUS MACULOSUS ................................13 Rationale..............................................................................................................................................13 Study sites...........................................................................................................................................13 Methods and materials ......................................................................................................................14 Glengarriff Nature Reserve.................................................................................................................14 Cashelkeelty Lowland Blanket Bog......................................................................................................17 Results and discussion.......................................................................................................................19 4. DEVELOPMENT OF A MONITORING STRATEGY FOR GEOMALACUS MACULOSUS ...................................24 Rationale..............................................................................................................................................24 Study sites...........................................................................................................................................24 Materials and methods ......................................................................................................................24 Experimental design...........................................................................................................................24 Power analysis ...................................................................................................................................25 Results and discussion.......................................................................................................................25 Baseline monitoring data....................................................................................................................25 Power analysis ...................................................................................................................................27 5. MOBILITY , SPATIAL DISTRIBUTION AND COMMUNITY STRUCTURE .....................................................32 Rationale..............................................................................................................................................32 Study sites...........................................................................................................................................32 Materials and methods ......................................................................................................................32 Slug tagging ......................................................................................................................................32 Experimental design...........................................................................................................................35 Results and discussion.......................................................................................................................37 Uragh Wood.......................................................................................................................................37 Leahill blanket bog..............................................................................................................................46 6. THREATS TO GEOMALACUS MACULOSUS ...............................................................................................50 Distribution and population dynamics of Geomalacus maculosus ____________________________________________________ Rationale............................................................................................................................................. 50 A. Impact of uncontrolled burning.................................................................................................. 50 Study sites......................................................................................................................................... 50 Methods and materials....................................................................................................................... 50 Results and discussion....................................................................................................................... 50 B. Impact of Rhododendron ponticum .............................................................................................. 52 Study sites......................................................................................................................................... 52 Materials and methods....................................................................................................................... 52 Results and discussion....................................................................................................................... 53 C. Impact of commercial afforestation ............................................................................................ 54 Study sites......................................................................................................................................... 54 Materials and methods....................................................................................................................... 54 Results and discussion....................................................................................................................... 55 7. POPULATION SIZE AND DENSITY ESTIMATES FOR GEOMALACUS MACULOSUS USING MARK -CAPTURE - RECAPTURE .............................................................................................................................................. 57 Rationale............................................................................................................................................. 57 Woodland ........................................................................................................................................... 57 Study sites......................................................................................................................................... 57 Materials and methods....................................................................................................................... 58 Results and discussion....................................................................................................................... 58 Blanket bog ........................................................................................................................................ 62 Study sites......................................................................................................................................... 62 Materials and methods....................................................................................................................... 62 Results and discussion....................................................................................................................... 63 MANAGEMENT RECOMMENDATIONS ....................................................................................................