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We investigated the causes of toe and foot loss and other deformities long observed in urban Brewer’s Blackbirds (Euphagus cyanocephalus) in southern California. Histopathologic evaluation showed that afflicted individuals suffered from infestations of mites compatible with Knemidokoptes spp. (scaly-leg mites). We developed a case definition based on gross lesions in confirmed cases and the scientific literature to search two large ornithological collections for specimens exhibiting these lesions. In evaluating specimens among seven species of the family Icteridae, we found 34 specimens in the two collections with lesions consistent with Knemidokoptes spp. Species afflicted included the Red-winged Blackbird (Agelaius phoeniceus; 12 of 978 specimens), Brewer’s Blackbird (10/337 specimens), Tricolored Blackbird (A. tricolor; 4/101 specimens), Brown-headed Cowbird (Molothrus ater; 4/828 specimens), and Great-tailed Grackle (Quiscalus mexicanus; 4/224 specimens). The earliest cluster of California specimens dated to 1962. Fourteen of the 34 specimens exhibiting the condition were collected since 1999. No specimens of the Yellow-headed Blackbird (Xanthocephalus xanthocephalus; 0 of 214 specimens) or Western Meadowlark (Sturnella neglecta; 0/278) were found with the condition.

Presentation at the March 23, 2022 SDMMP Management and Monitoring Coordination Meeting.

This survey protocol outlines the methods for conducting TRBL surveys across San Diego County in April and May 2021. A team of two surveyors will collect data using two different software packages-Ful

This survey protocol outlines the methods for conducting TRBL surveys across San Diego County in April and May 2023.

This survey protocol outlines the methods for conducting TRBL surveys across San Diego County in April and May 2021. A team of two surveyors will collect data using two different software packages-Fulcrum and ArcGIS Collector. All point data will be collected in Fulcrum and all polygon data will be collected in Collector. Please remain on trails and roads when on conserved lands.

Recording from the March 23, 2022 SDMMP Management and Monitoring Coordination Meeting. Presentations from Andrew Fisher (AECOM) and Loren Merrill (AECOM) on Tricolor Blackbird and Northern Harrier Surveys.

The Tricolored blackbird (Agelaius tricolor), a near-California endemic songbird with 95% of its historic breeding range within the state, holds the distinction of forming the largest breeding colonies of any North American songbird since the extinction of the Passenger pigeon (Ectopistes migratirius). Colonies consisting of 300,000 adult birds have been reported in the past (Neff 1937). Its close relationship to the Red-winged blackbird (Agelaius phoeniceus), a solitary, territorial breeder, makes the Tricolored blackbird (or tricolor) a rare and important subject for the evolutionary study of animal social systems, a significant contributor to the phenotypic diversity of California's avifauna (Hamilton 2000, Owens and Bennett 2000), and perhaps no more, a true wildlife "spectacle" (Mittermeier et al. 2003, Hamilton and Meese 2006).

This Conservation Plan (Plan) was developed to promote and facilitate cooperative efforts to ensure the long-term persistence of the Tricolored Blackbird (Agelaius tricolor) (tricolor). This species has suffered an alarming population decline. Loss of native habitats, a habit of nesting in extremely large and dense colonies, and an attraction for nesting in croplands nearing harvest conspired against this species? survival in California?s fertile valleys (see Biological Information in Appendix A). Concern over the future of the species united a diverse coalition of parties, the Tricolored Blackbird Working Group. This Plan is the work of that group and represents their commitment, and the other signatories to this document, to securing the future of tricolors. This work will be accomplished largely through voluntary, coordinated, and collaborative conservation actions of many interested stakeholders. Signatories to the Memorandum of Agreement (MOA) associated with this Plan commit to support the implementation of: (1) habitat conservation projects to benefit the species; (2) a research program to more thoroughly understand the species? life history; (3) a monitoring program to effectively document population trends and distribution; and (4) an outreach and education program to enhance public and private landowner awareness, and to build public support for conservation. It is the intention of the signatories to develop, enhance, and implement comprehensive and collaborative conservation efforts to ensure the long-term survival of tricolors.

Between April 24 and June 13, 2023, AECOM biologists conducted tricolored blackbird visual surveys and habitat assessments at 15 survey areas in San Diego County, 4 of which were new to the project (see GIS data submitted under separate cover).

Between April 10, 2021 and June 22, 2021 AECOM biologists conducted tricolored blackbird habitat assessments and surveys at 31 survey areas, primarily located in western San Diego County (see GIS data submitted under separate cover). This document is a summary of the results from those surveys.

From Introduction: The 2008 statewide survey was coordinated by Audubon California. The goal of this survey was to develop the best statewide population estimate possible, using volunteers across the state. We placed particular emphasis on expanding overall geographic coverage in the state and thorough surveys in Southern California counties due to concern for this sub-population. This report summarizes the 2008 survey results including comparison to past surveys, overall population status, regional variation in abundance, and breeding substrates.

INTRODUCTION: The San Diego Multiple Species Conservation program (MSCP) was developed for the conservation of plants and animals in the southeast portion of San Diego County. To assess the success of the MSCP and to evaluate the effectiveness of management actions implemented at the reserve level it is critical to monitor the species covered by the plan. Proper management of the preserve system will require ongoing collection and analysis of data on specific species and habitats to determine that species populations and habitats are being maintained by the MSCP preserve as expected. The purpose of this document is to provide protocols that the agencies and jurisdictions can apply to Risk Group 1 species (SDSU 2006) they share in common across the preserve. The intent is to begin collecting a unified and cohesive data set.