NYC Audubon provided data on bird deaths collected by volunteers over the span of about 7 months (April 1 2017 - November 11 2017). In total there were 26 volunteers who walked. To collect this data, each volunteer walked one of three routes in the early morning, several days of the week (there does not appear to be a clear pattern for which days the volunteers went out - likely each had a unique schedule). One of these routes was through midtown Manhattan, one through the west side of downtown Manhattan, and one through the east side of downtown Manhattan. Volunteers carefully examined perimeters of several high-risk (as identified by NYC Audubon scientists) buildings along the route, looking for dead birds on the sidewalk, in shrubbery, or on low-hanging ledges. If a volunteer found a dead bird, they followed a specific protocol to identify, log, handle, and dispose of the dead bird. To ensure volunteer compliance and efficacy, NYC Audubon ran "gold standard" trials where they placed frozen dead birds on the sidewalk for volunteers to find. Volunteer accuracy was very high, though these trials were complicated by building maintenance and other cleanup workers collecting the dead birds before volunteers could find them.