Science-Based Guidelines for Managing Special Issue Northern Goshawk Breeding Areas in Coastal British Columbia Erica L. McClaren , MSc, RPBio, Todd Mahon , MSc, RPBio, Frank I. Doyle , MSc, RPBio, & William L. Harrower, MSc, RPBio Abstract Northern Goshawks ( Accipiter gentilis laingi ) have been recognized as a species of man - agement concern in western North America for over 20 years. One of the most significant factors threatening Northern Goshawk populations in coastal British Columbia is the loss and fragmentation of structurally old and mature forests they use for breeding, foraging, and roosting. The goal of this report is to provide science-based guidelines for qualified environmental professonals to assist in their decision-making processes concerning Northern Goshawk habitat management in coastal British Columbia. These guidelines were previously unavailable or inconsistent and did not provide a thorough review of the scientific literature. The best management practices presented here are intended for use by qualified environmental professonals and managers when undertaking industrial activ - ities, primarily forestry, around Northern Goshawk breeding areas within coastal British Columbia. KEYWORDS : Accipiter gentilis laingi ; best management practices; breeding area; breeding habitat; coastal British Columbia; disturbance; foraging habitat; forest management; oc - cupancy; management guidelines; nesting habitat; northern goshawk; post-fledging area; reserve size; risk; science guidelines; territory; timing restrictions 1 JEM McClaren, E.L., T. Mahon, F.I. Doyle, and W.L. Harrower. 2015. Science-Based Guidelines for Managing Vol 15, No 2 Northern Goshawk Breeding Areas in Coastal British Columbia. Journal of Ecosystems and Management 15 (2):1–91. Published by the Journal of Ecosystems and Management: JOURNAL OF Ecosystems & http://jem-online.org/index.php/jem/article/viewFile/576/506 Management Location of accompanying documentation SCIENCE-BASED GUIDELINES Further information on individual studies, projects, or supplemental information used in FOR MANAGING this report is available upon request directly from the report authors. NORTHERN GOSHAWK BREEDING AREAS McClaren, Mahon, Doyle, & Harrower Table of Contents Abstract ...............................................................................................................................1 Executive Summary ...........................................................................................................4 1 Introduction .................................................................................................................6 1.1 Distribution ..............................................................................................................7 1.2 Ranking status ..........................................................................................................8 1.3 Regulatory framework ..............................................................................................9 1.3.1 International ..........................................................................................................9 1.3.2 Federal ....................................................................................................................9 1.3.3 Provincial (British Columbia) .............................................................................10 2 Scope and Objectives .................................................................................................10 2.1 Science-based management ...................................................................................11 3 Long-term Studies on Coastal Goshawks .................................................................13 3.1 Vancouver Island ....................................................................................................13 3.2 Haida Gwaii .............................................................................................................15 3.3 Summary of other coastal goshawk study locations ............................................16 3.3.1 Mainland coastal British Columbia .....................................................................16 3.3.2 United States ........................................................................................................16 3.4 Analyses of coastal goshawk data to support these guidelines .............................16 4 Breeding Ecology of Coastal Goshawks ....................................................................17 4.1 Individual age .........................................................................................................17 4.2 Breeding chronology ..............................................................................................17 4.3 Productivity, occupancy, and survival ...................................................................18 4.4 Habitat characteristics ...........................................................................................19 4.5 Nest tree and breeding area spacing patterns .......................................................20 4.6 Foraging ..................................................................................................................20 5 Coastal Goshawk Territory Components ..................................................................21 5.1 Nest site and nest area characteristics ..................................................................25 5.2 Post-fledging area characteristics and fledgling movements ...............................30 5.3 Estimating the size of breeding areas in coastal British Columbia .....................32 5.4 Home range and foraging habitat ..........................................................................34 2 6 Responses of Coastal Goshawks to Breeding Area Disturbance .............................39 6.1 Direct disturbance ..................................................................................................39 6.2 Indirect disturbance from habitat alteration and loss within breeding areas .....41 JEM Vol 15, No 2 7 Other Sources of Variation in Breeding Area Occupancy and Reproduction .........45 JOURNAL OF 7.1 Individual quality ...................................................................................................45 Ecosystems & Management 7.2 Annual and longer-term weather patterns ............................................................46 SCIENCE-BASED GUIDELINES 7.3 Prey, predators, and competitors ...........................................................................46 FOR MANAGING NORTHERN GOSHAWK BREEDING AREAS 8 Best Management Practices for Coastal Goshawk Breeding Areas .........................47 8.1 Summary of best management practices for coastal goshawk breeding areas ...49 McClaren, Mahon, Doyle, & Harrower 8.2 Defining the breeding area ....................................................................................50 8.3 Reserve design ........................................................................................................52 8.4 Minimizing direct disturbance: timing restrictions .............................................53 8.5 Managing multiple breeding areas ........................................................................54 8.6 Foraging area considerations ................................................................................54 9 Strategic and Operational Planning Considerations ................................................56 9.1 Co-location of breeding area reserves ...................................................................56 9.2 Windthrow considerations in reserve design ........................................................59 9.3 Habitat quality evaluation: operational and strategic considerations .................59 9.4 Enhancing forest structure to promote goshawk habitat characteristics ...........60 10 Knowledge Gaps and Key Research Questions .........................................................61 11 Data Management ......................................................................................................64 Acknowledgements ...........................................................................................................65 Notes .................................................................................................................................66 References .........................................................................................................................67 Appendix 1: Glossary ........................................................................................................79 Appendix 2: Key to Abbreviations of Biogeoclimatic Subzones and Tree Species .........83 Appendix 3: Updated Analyses for Coastal Best Management Practices: Detailed Methodology ..................................................................................84 Appendix 4: Breeding Area Delineation and Monitoring ................................................87 Author Information ..........................................................................................................91 3 JEM Vol 15, No 2 JOURNAL OF Ecosystems & Management Executive Summary SCIENCE-BASED GUIDELINES he two subspecies of Northern Goshawks ( Accipiter gentilis atricapillus, Accipiter FOR MANAGING gentilis laingi ) occurring in western North America have been a management con - NORTHERN GOSHAWK BREEDING AREAS Tcern for over 20 years. One of the most significant factors threatening Northern Goshawk populations