ANALYSIS OF THE POTENTIAL IMPACTS OF DOMESTICATED FERRETS UPON WILDLIFE, AGRICULTURE, AND HUMAN HEALTH IN NORTH AMERICA, WITH A FOCUS UPON CALIFORNIA, BASED UPON LITERATURE REVIEW AND SURVEY OF NORTH AMERICAN GOVERNMENTAL AGENCIES University Enterprises, Inc., Grant Number 517021 13 September 2010 Prepared for: California Fish and Game Commission Prepared by: G. O. Graening, PhD, MSE Department of Biological Sciences California State University, Sacramento 6000 J Street, Sacramento, CA 95819 SURVEY OF IMPACTS OF FERRETS TABLE OF CONTENTS DISCLAIMER ........................................................................................................................................................................ 3 ABSTRACT ........................................................................................................................................................................... 3 1. INTRODUCTION ......................................................................................................................................................... 6 2. HISTORY OF REGULATIONS AND POLICIES IN CALIFORNIA ....................................................................... 6 3. REGULATION OF FERRETS OUTSIDE OF CALIFORNIA ............................................................................... 18 3.1. Regulatory Classification ................................................................................................................................... 18 3.1.1. Summary and Opinion ............................................................................................................................... 19 3.2. Prohibitions on Importation or Possession ..................................................................................................... 19 3.2.1. Summary and Opinion ............................................................................................................................... 21 3.3. Environmental Impact Review for Regulation ................................................................................................ 21 3.3.1. Summary and Opinion ............................................................................................................................... 22 3.4. Regulations in Other Countries ........................................................................................................................ 22 4. STEPS TOWARD LEGALIZATION ........................................................................................................................ 22 4.1. Enact Legislation ................................................................................................................................................ 22 4.1.2. Summary and Opinion ............................................................................................................................... 23 4.2. Change of Policy by the State of California .................................................................................................... 23 4.2.1. Addressing Concerns and Objections Raised by CDFG ...................................................................... 25 4.2.2. Performance of a Controlled Experiment or Pilot Study ....................................................................... 25 4.2.3. Performance of a Risk Analysis and/or Cost-Benefit Analysis ............................................................ 27 4.2.4. Summary and Opinion ............................................................................................................................... 30 5. DATA COMPILATION METHODS AND RESULTS ............................................................................................. 31 5.1. Literature Review................................................................................................................................................ 31 5.1.5. Journal and Textbook Review .................................................................................................................. 31 5.1.6. Newspaper Article Review ........................................................................................................................ 31 5.2. Interviews and Other Sources .......................................................................................................................... 31 5.3. State Agency Questionnaire ............................................................................................................................. 32 5.3.7. Questionnaire Methods ............................................................................................................................. 32 5.3.8. Questionnaire Results ............................................................................................................................... 32 5.4. Limitations / Data Deficiencies ......................................................................................................................... 35 6. TAXONOMY, ORIGIN, AND DISTRIBUTION ....................................................................................................... 35 6.1. Taxonomy and Nomenclature .......................................................................................................................... 35 6.1.1. Scientific Nomenclature ............................................................................................................................. 35 6.1.2. State Agency Nomenclature ..................................................................................................................... 37 6.1.3. Summary and Opinion ............................................................................................................................... 37 6.2. Origin and Distribution ....................................................................................................................................... 38 6.2.1. Origins of the Ferret ................................................................................................................................... 38 6.2.2. Introduction into North America ................................................................................................................ 42 6.2.3. Distribution of Mustelids in California ...................................................................................................... 43 6.2.4. Summary and Opinion ............................................................................................................................... 44 7. CENSUSING FERRETS .......................................................................................................................................... 44 7.1. Why is the census of ferrets important? ......................................................................................................... 44 7.2. Estimates from Published Literature ............................................................................................................... 44 7.3. Estimates from Surveyed Agency Personnel ................................................................................................. 47 7.4. Estimates from the Pet Trade Industry ........................................................................................................... 48 7.5. Summary and Opinion ....................................................................................................................................... 48 8. ANALYSIS OF POTENTIAL WILDLIFE ISSUES ................................................................................................. 49 8.1. Reasons for Concern ......................................................................................................................................... 49 8.2. Life History Traits of Ideal Invaders Compared to Ferrets ........................................................................... 50 8.2.1. Life History Traits of Ideal Invaders ......................................................................................................... 50 8.2.2. Life History Traits of Ferrets ..................................................................................................................... 51 CSUS Biological Sciences Dept. Page 1 SURVEY OF IMPACTS OF FERRETS 8.2.3. Ferret Life Expectancy and Reproductive Potential .............................................................................. 56 8.2.4. Diet and Hunting Ability ............................................................................................................................. 58 8.2.5. Other Relevant Traits ................................................................................................................................. 60 8.2.6. Summary and Opinion ............................................................................................................................... 62 8.3. Ability of Ferrets to Escape Confinement ....................................................................................................... 62 8.3.1. Summary and Opinion ............................................................................................................................... 64 8.4. Regional Case Studies of Feral Ferrets .......................................................................................................... 64 8.4.1. European Case Studies ...........................................................................................................................