Cogswell 1948 Lavia stellata Dec. 18. Tomasas Bay, Marin Co., Calif. One of the most spectacular sights here today was the one of dozens & dozens of loons passing up & down the bay practically all the time. There must have been several hundred altogether, probably half or so of this species, though all 3 species were identified. Many were on the water mostly well spread out from one another, a meanwhile flocks of 20-30 birds each flew past, a few of them low over the water but mostly about 50-100 feet up. It was a sight I had never before experienced. Compared to Brandts cormorants, which were also passing up & down the bay in large numbers the loons flew in much looser flocks, with no apparent "formation". Their wing beats are slightly faster than cormorants. Without actually timing them, I would judge the smaller loons (both sp.) to have a beat of about 3 per second. The sound produced by their wings as they passed overhead was distinctly louder than that of the cormorants, though far less than that of the scoters & golden eyes.