University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln US Fish & Wildlife Publications US Fish & Wildlife Service 2000 Cassin’s Sparrow (Aimophila cassinii) Status Assessment and Conservation Plan Janet M. Ruth U.S. Geological Survey, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/usfwspubs Part of the Aquaculture and Fisheries Commons Ruth, Janet M., "Cassin’s Sparrow (Aimophila cassinii) Status Assessment and Conservation Plan" (2000). US Fish & Wildlife Publications. 170. https://digitalcommons.unl.edu/usfwspubs/170 This Article is brought to you for free and open access by the US Fish & Wildlife Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in US Fish & Wildlife Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Cassin’s Sparrow (Aimophila cassinii) Status Assessment and Conservation Plan Biological Technical Publication BTP-R6002-2000 Janet M. Ruth Research Ecologist U.S. Geological Survey Midcontinent Ecological Sicience Center 4512 Mc Murry Avenue Fort Collins, CO 80525-3400 970-226-9487 FAX 970-226-9230 [email protected] For additional copies or further information, contact: Nongame Migratory Bird Coordinator, Region 6 U.S. Fish & Wildlife Service P.O. Box 25486 Denver Federal Center Denver, CO 80225 March 2000 i Recommended citation: Ruth, J.M. 2000. Cassin’s Sparrow (Aimophila cassinii) status assessment and conservation plan. Biological Technical Publication BTP-R6002-1999. U.S. Department of the Interior, Fish and Wildlife Service, Denver, CO. ii U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan Cassin’s Sparrow - March 2000 Table of Contents TABLE OF CONTENTS TABLE OF CONTENTS ............................................................ iii LIST OF TABLES AND FIGURES ............................................ vii EXECUTIVE SUMMARY .......................................................... 1 ACKNOWLEDGMENTS ............................................................ 2 TAXONOMY ............................................................................. 3 LEGAL STATUS ........................................................................ 3 United States ................................................................... 3 Mexico ........................................................................... 4 DESCRIPTION .......................................................................... 4 Plumage .......................................................................... 4 Adult ........................................................................ 4 Juvenile ................................................................... 5 NATURAL HISTORY ................................................................ 5 Song ............................................................................... 5 Diet ................................................................................ 6 Territory and Site Fidelity ................................................... 6 Breeding Ecology ............................................................. 8 Migratory Behavior ......................................................... 10 RANGE .................................................................................... 10 Breeding ....................................................................... 11 Migration ....................................................................... 12 WIntering ...................................................................... 13 Distribution Changes in Response to Precipitation ............... 14 Theory Regarding Unusual “Migration” Patterns in Cassin’s Sparrows ............................... 17 MONITORING ACTIVITIES ............................................... 18 Breeding Bird Survey (BBS) ....................................... 18 Christmas Bird Count (CBC) ...................................... 19 Breeding Bird Atlases ................................................. 19 POPULATION ESTIMATES AND TRENDS ..................... 19 Population Estimates .................................................. 19 Trends ......................................................................... 19 Possible Explanation of Trends ................................... 22 HABITAT............................................................................... 24 Breeding season habitat requirements ........................ 25 Winter habitat requirements ....................................... 27 MANAGEMENT ................................................................... 28 Grazing........................................................................ 28 Burning ....................................................................... 31 Conservation Reserve Program (CRP) ....................... 33 Tamarisk ..................................................................... 33 THREATS.............................................................................. 34 Habitat........................................................................ 34 Overutilization for Commercial, Recreational, Scientific, or Educational Purposes ....................... 34 Disease or Predation ................................................... 34 Inadequacy of Existing Regulatory Mechanisms ......... 35 Other natural or ManmadeFactors .............................. 35 Pesticides .............................................................. 35 Population size ..................................................... 35 Nest Parasitism .................................................... 35 U.S. Fish and Wildlife Service - Status Assessment and Conservation Plan Cassin’s Sparrow - March 2000 iii Table of Contents Suburban Development........................................... 35 Exotic Grasses ........................................................ 36 Grazing .................................................................. 37 Brush Control......................................................... 37 Tamarisk ................................................................ 38 ASSESSMENT AND RECOMMENDATION ............................ 38 Recommendation on current status ................................... 38 CONSERVATION .................................................................... 39 Research Priorities ......................................................... 40 LITERATURE CITED .............................................................. 42 APPENDIX A STATE SUMMARIES ........................................................... 51 Natural Heritage Program State Ranks Defined ........ 51 UNITED STATES .................................................................. 52 ARIZONA .............................................................................. 52 Summary..................................................................... 52 BBS ............................................................................. 52 CBC ............................................................................ 52 Atlas............................................................................ 52 Research / Monitoring ................................................. 53 Major Populations ....................................................... 55 State Status ................................................................. 55 Natural Heritage Rank ............................................... 55 Habitat Condition ........................................................ 55 Threats........................................................................ 55 Literature Cited .............................................................. 55 NEW MEXICO ......................................................................... 58 Summary........................................................................ 58 BBS ............................................................................. 59 CBC ............................................................................. 60 Atlas ............................................................................. 60 Research / Monitoring ..................................................... 60 Major Populations ........................................................... 62 State Status ................................................................... 62 Natural Heritage Rank .................................................... 62 Habitat Condition ............................................................ 62 Threats ......................................................................... 63 Literature Cited .............................................................. 63 TEXAS 65 Summary....................................................................... 65 BBS ............................................................................. 65 CBC ............................................................................. 66 Atlas ............................................................................. 67 Research / Monitoring ..................................................... 67 Major Populations ........................................................... 67 State Status ................................................................... 68 Natural Heritage Rank .................................................... 68 Habitat Condition ............................................................ 68 Threats ........................................................................