Waterfowl Migration on Klamath Basin National Wildlife Refuges 1953-2001 USGS/BRD/BSR —2003-0004 U.S. Department of the Interior U.S. Geological Survey Cover: Background photo, tundra swans on water and Canada geese in flight with snowcovered hills in background at Lower Klamath National Wildlife Refuge, T. A. Blake; inset, white-fronted geese in flight with Mt. Shasta in the background at Tule Lake National Wildlife Refuge, D. Menke, USFWS. Waterfowl Migration on Klamath Basin National Wildlife Refuges 1953-2001 By David S. Gilmer and Julie L. Yee, U.S. Geological Survey, and David M. Mauser and James L. Hainline, U.S. Fish and Wildlife Service Biological Science Report USGS/BRD/BSR—2003-0004 U.S. Department of the Interior U.S. Geological Survey iii U.S. Department of the Interior Gale A. Norton, Secretary U.S. Geological Survey Charles G. Groat, Director U.S. Geological Survey, Reston, Virginia: 2004 For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, it contains copyrighted materials that are noted in the text. Permission to reproduce those items must be secured from the individual copyright owners. Suggested citation: Gilmer, D.S., Yee, J.L., Mauser, D.M., and Hainline, J.L., 2004, Waterfowl migration on Klamath Basin National Wildlife Refuges 1953-2001: U.S. Geological Survey, Biological Resources Discipline Biological Science Report USGS/ BRD/BSR—2003-0004, 66 p. Library of Congress Cataloging-in-Publication Data Waterfowl migration on Klamath Basin National Wildlife Refuges, 1953-2001 / by David S. Gilmer . [et al.] . p. cm.--(Biological science report ; USGS/BRD/BSR-2003-0004) Includes bibliographical references (p. 66) . 1. Waterfowl--Migration--Klamath River Watershed (Or. and Calif.) I. Gilmer, David S. II. Series. SK331.W385 2004 iii U.S. Department of the Interior Contents Gale A. Norton, Secretary U.S. Geological Survey Abstract.......................................................................................................................................................... 1 Charles G. Groat, Director Introduction ................................................................................................................................................... 2 Areas Surveyed............................................................................................................................................. 2 Refuge Complex ................................................................................................................................... 2 Lower Klamath National Wildlife Refuge......................................................................................... 2 Tule Lake National Wildlife Refuge................................................................................................... 3 Clear Lake National Wildlife Refuge................................................................................................. 4 Upper Klamath National Wildlife Refuge......................................................................................... 5 Klamath Marsh National Wildlife Refuge ........................................................................................ 5 Methods ......................................................................................................................................................... 6 Aerial Surveys ...................................................................................................................................... 6 Identifying and Counting Waterfowl................................................................................................. 6 Data Files and Handling...................................................................................................................... 6 Characteristics of Survey Data ......................................................................................................... 6 Terminology........................................................................................................................................... 7 For more information about the USGS and its products: Seasons........................................................................................................................................ 7 Telephone: 1-888-ASK-USGS Waterfowl Abundance............................................................................................................... 7 World Wide Web: http://www.usgs.gov/ Multi-Year Averaging ................................................................................................................. 7 Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply Seasonal Chronology ................................................................................................................. 8 endorsement by the U.S. Government. Other Data Files.................................................................................................................................... 8 Results and Discussion................................................................................................................................ 8 Reliability of Waterfowl Surveys....................................................................................................... 8 Waterfowl Abundance on Klamath Basin National Wildlife Refuge Complex.......................... 8 All Waterfowl............................................................................................................................... 8 Overview ............................................................................................................................. 8 Long-Term Period Versus Most Recent Period ............................................................ 8 Early Period Versus Recent Period................................................................................. 9 Composition of Waterfowl Groups and Species.................................................................. 10 Overview ........................................................................................................................... 10 Long-Term Period Versus Most Recent Period .......................................................... 11 Early Period Versus Recent Period............................................................................... 11 Monthly Changes in Composition ................................................................................. 12 Potential Influence of Central Valley Habitats..................................................................... 12 Relation to Other Surveys........................................................................................................ 12 Northern Breeding Grounds .......................................................................................... 12 California Midwinter........................................................................................................ 13 Waterfowl Abundance on Individual Refuges.............................................................................. 13 Lower Klamath National Wildlife Refuge.............................................................................. 13 Tule Lake National Wildlife Refuge........................................................................................ 14 Upper Klamath, Klamath Marsh, and Clear Lake National Wildlife Refuges.................. 15 Changing Status of Prominent Species ......................................................................................... 16 Northern Pintail......................................................................................................................... 16 iv v Changing Status of Prominent Species—Continued Mallard ....................................................................................................................................... 17 White-Fronted Geese............................................................................................................... 18 Cackling Canada Geese........................................................................................................... 19 White Geese .............................................................................................................................. 19 Other Waterfowl........................................................................................................................ 20 Migration Chronology ....................................................................................................................... 20 Autumn ....................................................................................................................................... 20 Long-Term Period Versus Most Recent Period .......................................................... 20 Early Period Versus Recent Period............................................................................... 21 Spring ........................................................................................................................................ 21 Long-Term Period Versus Most Recent Period .......................................................... 21 Early Period Versus Recent Period..............................................................................