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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 57 other seasonal wetlands, riparian scrub habitats, and open marsh borders. Wintering Tricolored Blackbirds often congregate in large, mixed-species blackbird flocks that forage in grasslands and agricultural fields with low-growing vegetation. Breeding habitats include wetland and silage fields with tall, dense cover near open water. Nesting colonies range in size from 50 nests to over 20,000 in an area of 10 acres or less (CDFW 2008a). Breeding usually occurs from mid-April into late July (CDFW 2008a). Suitable habitat for Tricolored Blackbird is found within the project footprint, and several recorded occurrences are located near Impact Areas, therefore this species has a moderate potential to occur. Although wintering birds and a few individuals have been observed during breeding season, no nesting colonies have been identified within 1/4 mile of the Study Area. Implementation of Mitigation Measures MM AES-1, MM BIO-1 and MM BIO-7 would reduce potential impacts to Tricolored Blackbird to: Less than Significant with Mitigation Incorporated. MM BIO-7: Tricolored Blackbird To minimize and avoid the potential impacts to Tricolored Blackbird that may occur within the Study Area the following general measures will be implemented: a. For soil investigation field activities that will occur March 15- July 31 in areas with potential breeding habitat for Tricolored Blackbird, a pre-activity survey for breeding colonies will be conducted by a qualified biologist within 1,300 feet of Impact Areas a maximum of 72 hours prior to the onset of soil investigation activities. The qualified biologist(s) must, at a minimum, have experience conducting surveys to identify Tricolored Blackbird and associated habitat that could occur on site. b. For soil investigation field activities that will occur August 1 – March 14 in areas with potential roosting habitat for Tricolored Blackbird, a pre-activity survey for roosting Tricolored Blackbirds will be conducted during the nonbreeding season within 300 feet of Impact Areas a maximum of 72 hours prior to the onset of soil investigation activities by a qualified biologist. c. If active Tricolored Blackbird breeding colonies or roost sites are identified within or adjacent to an Impact Area, a buffer will be put in place to ensure that the birds are not disturbed during work activities. This buffer will be up to 1,300 feet but may be reduced to a minimum of 300 feet, dependent on- site conditions and at the discretion of the qualified biologist. Grasshopper Sparrow (Ammodramus savannarum)