Survey and monitor northern harrier (circus hudsonius hereafter, harrier) nests in the sacramento valley to assess breeding population status and inform habitat management

The California Department of Fish and Wildlife (CDFW) was awarded a $343,305 Formula Grant from the U.S. Fish and Wildlife Service under the State Wildlife Grants (CFDA 15.634) program. The purpose of the grant is to survey and monitor Northern Harrier (Circus hudsonius) nests in the Sacramento Valley over two breeding seasons (2025 and 2026) to assess breeding population status and inform habitat management. The research will be conducted by a graduate student and field technician under the guidance of a major professor and graduate thesis committee at the University of Missouri. CDFW staff with expertise in Northern Harrier ecology will coordinate the project's efforts with their ongoing research and monitoring on state wildlife areas, national wildlife refuges, and private agricultural lands. Findings from this project will help determine the effects of habitat characteristics on Northern Harrier breeding success and inform management strategies to benefit this species of special concern, as well as other nesting birds.

Northern harrier breeding populations will be assessed on various state wildlife areas, national wildlife refuges, and private agricultural lands in the sacramento valley across two breeding seasons (april-july, 2025 and 2026). Research will be conducted by a graduate student and field technician under the guidance of a major professor and graduate thesis committee at the school of natural resources at the university of missouri. California department of fish and wildlife (hereafter, department) staff with expertise in northern harrier ecology will coordinate with the department s lands program on ongoing research on these same study areas aimed at monitoring nesting waterfowl, as well as assessing the efficacy of various landowner delayed harvest and wildlife-friendly land management practice incentive programs on adjacent private lands. Access to the primary study areas in this project will be facilitated through the lands program and their ongoing research and monitoring on wildlife areas and national wildlife refuges, as well as through contracts that obligate access for wildlife monitoring on private lands. Department staff will also coordinate with the california rice commission for access to other private lands outside of contracts with the department s lands program. Researchers working on this project and those working on the department s lands program research and monitoring projects (U.S. Geological survey and california waterfowl association) will coordinate and collaborate their efforts to ensure accurate data collection, data sharing, and to reduce redundancy. This project will address several management and research recommendations in the northern harrier species of special concern species (SSC) account (shuford and gardali 2008), including determining if reproductive success differs between natural (wetlands and grasslands) and anthropogenic (croplands and pastures) habitats and determining the effects of patch size and habitat fragmentation on habitat use and nest success. Results from this work will inform grassland, wetland, and agricultural habitat management to benefit not only northern harrier breeding populations but will be used to assess efficacy of various nesting bird habitat incentive programs managed by the department s lands program, as well.