The Black Skimmer is a gregarious species, nesting in colonies that can exceed 1,000 birds. On the west coast they are seldom seen often north of the Oakland Bay Bridge, but they are regular at Radio Road in Redwood City. On my Jan 18 visit I noted 4 of them loafing on a close mud bar in the main pond.
The white nape will be gone with the advent of alternate plumage. Huge bill favors a male. No doubt you've seen videos of these long-winged tern-like birds flying low over the water with the lower mandible cutting a swath through the water, ready to snap shut when a prey item is encountered. Since they feed by touch they often are foraging at night, and most often spend the day resting with their buddies. You'd think that there would be serious drag from the large beak cutting through the water, but in fact the bill is so greatly compressed laterally that it meets with minimal resistance. Old shot from Florida shows the bill face on:
Many taxonomists currently place the Skimmers in a subfamily Rhynchopinae, within in the family Laridae (Gulls, Terns and Skimmers). Some think skimmers are more closely related to terns than to the gulls. In the North America the Black Skimmer is a coastal bird, whereas the other 2 Skimmer species (African Skimmer and Indian Skimmer) are found on the banks of rivers. Along our East Coast the birds head south to Florida for the winter, while those seen in California are largely sedentary. They are a species of concern, as reproductive success if quite variable (most years only 50% of pairs fledge chicks, and 2 chicks is about average (BNA #108, Gochfeld and Burger). Nesting failure more common in small colonies.
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