A Horned Grebe in August is, based on eBird data, a very infrequent sighting in Eastern Mass. This cooperative bird was drifting along about 150 feet offshore at high tide on the bay side about 1/2 mile south of the Bridge. This photo was taken from my car at full zoom (400mm).

It appears to be in a transitional plumage with the head and neck still in alternate (breeding) plumage though the "ears" seem to be white rather than the gold of full breeding plumage. The body, on the other hand is further along as it is starting to show the pale flanks of the winter (basic) plumage.