The Significance of Rubbish Tips As an Additional Food Source for the Kelp Gull and the Pacific Gull in Tasmania
The Significance of Rubbish Tips as an Additional Food Source for the Kelp Gull and the Pacific Gull in Tasmania by e. e--~'" (& G. M. Coulson, B.A. (Hans.), Dip.Ed. (Melb.) and .J~ R.I. Coulson, B .Sc., Dip.Ed. (Melb.) Being a thesis submitted in part fulfilment of the requirements for the degree of Master of Environmental Studies Centre for Environmental Studies University of Tasmania August, 1982 nl\, (l,_ '/ Cl-- \'\~'.2. ACKNOWLEDGEMENTS We are grateful to our supervisors, Dr. A.M.M. Richardson and Dr. J.J. Todd, and our external advisors, Mr. A.W.J. Fletcher and Mr. J.G.K. Harris, for their guidance in the preparation and planning of this thesis. Mrs. L. Ramsay typed the thesis. Mr. D. Barker (Tasmanian Museum, Hobart) and Mr. R.H. Green (Queen Victoria Museum, Launceston) gave us access to their gull collections. Mr. G. Davis assisted with the identification of chitons. Officers of the Tasmanian National Parks and Wildlife Service provided information, assistance, equipment and specimens, and officers of the Tasmanian Department of the Environment gave us information on tips. The cities and municipalities in south-east Tasmania granted permission to study gulls at tips under their control, and we are particularly grateful for the co-operation shown by council staff at Clarence, Hobart and Kingborough tips. Mr. R. Clark allowed us to observe gulls at Richardson's Meat Works, Lutana. CONTENTS ABSTRACT 1 1. INTRODUcriON 3 2. GULL POPULATIONS IN THE NORTHERN HEMISPHERE 7 2.1 Population Increases 8 2.1.1 Population size and rates·of change 10 2.1.2 Growth of breeding colonies 13 2.2 Reasons for the Population Increase 18 2.2.1 Protection 18 2.2.2 Greater food availability 19 2.3 Effects of Population Increase 22 2.3.1 Competition with other species 22 2.3.2 Agricultural pests 23 2.3.3 Public health risks 24 2.3.4 Urban nesting 25 2.3.5 Aircraft bird-strikes 25 2.4 Future Trends 26 3.
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