DRAFT Western Great Lakes Northern Goshawk Conservation Assessment DRAFT Conservation Assessment for Northern Goshawk (Accipiter gentilis) Linnaeus in the Western Great Lakes Photo credit: Phil Detrich, USFWS USDA Forest Service, Eastern Region August 10, 2007 Dr. John Curnutt U. S. Forest Service Milwaukee, Wisconsin This document is undergoing peer review, comments welcome 1 DRAFT Western Great Lakes Northern Goshawk Conservation Assessment DRAFT EXECUTIVE SUMMARY TBD ACKNOWLEDGEMENTS TBD 2 DRAFT Western Great Lakes Northern Goshawk Conservation Assessment DRAFT Table Of Contents EXECUTIVE SUMMARY .......................................................................................................................... 2 ACKNOWLEDGEMENTS ......................................................................................................................... 2 INTRODUCTION ........................................................................................................................................ 8 APPROACH , SCOPE AND METHODS OF ASSESSMENT ................................................................................. 10 THE DATA ................................................................................................................................................. 11 STRUCTURE AND LAYOUT OF THIS ASSESSMENT ...................................................................................... 11 THE GOSHAWK ....................................................................................................................................... 12 NOMENCLATURE AND TAXONOMY ........................................................................................................... 12 DESCRIPTION ............................................................................................................................................ 13 GLOBAL /N ORTH AMERICA PRE -SETTLEMENT DISTRIBUTION ................................................................... 13 HABITS , NESTING AND REPRODUCTION .................................................................................................... 17 Foraging.............................................................................................................................................. 17 Seasonal Shifts in Diet....................................................................................................................................19 Seasonal Shifts in Diet.....................................................................................................................................20 Nesting and Reproduction................................................................................................................... 20 Nests................................................................................................................................................................20 The Breeding Cycle.........................................................................................................................................21 SUMMARY ................................................................................................................................................. 23 GOSHAWK HABITAT.............................................................................................................................. 23 BREEDING SEASON HABITAT ..................................................................................................................... 24 Nest tree .............................................................................................................................................. 24 Nest site/Nesting area.......................................................................................................................... 25 Caveats for Interpreting the Research ................................................................................................ 27 Goshawk Habitat at the Landscape-scale ........................................................................................... 29 Post-fledging Area...........................................................................................................................................29 Home Range/Foraging Area............................................................................................................................31 GOSHAWK WINTER HABITAT ................................................................................................................... 33 GOSHAWK PREY HABITAT ........................................................................................................................ 34 Sciurids................................................................................................................................................ 35 Ruffed grouse....................................................................................................................................... 35 Eastern chipmunk................................................................................................................................ 37 Hares and Rabbits............................................................................................................................... 39 Ensemble ............................................................................................................................................. 39 SUMMARY OF GOSHAWK HABITAT .......................................................................................................... 41 STATUS AND DISTRIBUTION OF GOSHAWK HABITAT IN THE WGLR ........................................................ 42 Status and trends at the 40 ha scale .................................................................................................... 48 Summary of goshawk habitat status and trends .................................................................................. 51 GOSHAWK POPULATION ECOLOGY ................................................................................................ 51 WHAT IS A GOSHAWK POPULATION ?........................................................................................................ 51 Floaters ............................................................................................................................................... 51 Breeding Adults................................................................................................................................... 51 To breed or not.................................................................................................................................... 52 To move or not..................................................................................................................................... 52 Immigrating Goshawks........................................................................................................................ 53 THE ELUSIVE Λ .......................................................................................................................................... 54 Vital Rates ........................................................................................................................................... 54 Longevity ........................................................................................................................................................54 Age at first reproduction..................................................................................................................................54 Age-specific survival.......................................................................................................................................55 Age-specific reproduction ...............................................................................................................................56 3 DRAFT Western Great Lakes Northern Goshawk Conservation Assessment DRAFT λ revisited ............................................................................................................................................ 56 LIMITING FACTORS ................................................................................................................................... 56 Food .................................................................................................................................................... 57 Space ................................................................................................................................................... 58 Siblicide/Cannibalism ......................................................................................................................... 58 Predation............................................................................................................................................. 59 Parasites.............................................................................................................................................. 62 Interspecific Competition .................................................................................................................... 62 SUMMARY OF GOSHAWK POPULATION ECOLOGY ..................................................................................... 65 HUMANS AND THE GOSHAWK ........................................................................................................... 66 LEGAL AND CONSERVATION STATUS .......................................................................................................