The Black Skimmer

Sub-adult Black Skimmer close-up

A sub-adult Black Skimmer close-up over a pond at San Joaquin Wildlife Sanctuary in Irvine, California

The Black Skimmer (Rynchops niger) is a  wonderfully weird bird with a very broad distribution across the southern half of North America, where it is found almost exclusively at coastal locations or within ~20 miles of the shore. They are primarily year-round residents there, though some migrate to winter on shores of the Gulf of Mexico, some going as far south as the western Yucatan. A large population of Black Skimmers resides year-round in a range roughly corresponding to the entire Amazon drainage basin. Black Skimmers are easily recognizable by their long, pointed wings, black above and grayish under the flight feathers, grading to white below. Black Skimmers have clean white underparts, throat, neck collar (non-breeding only) and around the bill. Their feet and the inner bills are bright orange; the tips of both mandibles are black. Juvenile Black Skimmers are more brownish-gray on the upper surface, and have relatively dull orange feet and inner bill parts. At birth, juvenile skimmers bill parts are of equal length, but by the time they fledge in four weeks, the lower mandible is fully a centimeter longer than the upper one.

Black Skimmer Conservation Status

Black Skimmer feeding on the pond at Mason Regional Park

Black Skimmer feeding on the pond at Mason Regional Park, Orange County, CA

The Black Skimmer is “our skimmer” in that it is unique to the Western Hemisphere. There are two other species of skimmer worldwide: the African Skimmer (Rynchops flavirostris) and Indian Skimmer (Rynchops albicollis). African Skimmers are classified as near-threatened, with a population of 15000 – 25000 individuals. Indian Skimmers are the most endangered with an estimated 6000 – 10000 individuals remaining in the world, and under a variety of threats. By contrast, Black Skimmers are a species of “least concern”, estimated at 65000 – 70000 breeding birds in the population, due  largely part to their bigger range. Taxonomically, skimmers were classed as a type of odd tern for several hundred years. Then modern research indicated that they belonged in their own group, though still in the larger order of the Charadriiformes, tucked between the terns and the auks.

Feeding Strategy

Sub-adult Black Skimmer feeding

Sub-adult Black Skimmer feeding

What makes skimmers particularly interesting is their way of making a living, using a bill that is significantly longer in the lower mandible than the upper one. The lower bill is stuck into the water like a plow as the bird flies at low altitude over the water’s surface. This is possible because the lower bill is streamlined like a knife edge so it offers little resistance to the water. The lower bill then strikes organisms swimming near the water’s surface, whereupon the skimmer, using reflexes of incredible speed, snaps the bill shut, pinning it

Side view of taxidermy specimen bill

Side view of taxidermy specimen bill – specimen courtesy of Sea and Sage Audubon Society

between the two knife edges of the upper and lower bills. Even with those phenomenal reflexes, the bird also can be observed (in slow-motion clips) to actually compress its neck inward and duck to secure prey. To maximize opportunities for capturing prey, the skimmer flies quite slowly using a very shallow wingbeat to hold the bill steady in the water. This mode of flight makes the skimmer incredibly graceful in motion, and also an irresistible subject for photography. This method of feeding is completely tactile so that the birds can feed in near complete darkness. They are often visible doing so after dusk when they appear as dark blobs cruising low over the water. All three skimmer species feed by this means. Simply incredible!

Breeding and Behavior

A sub-adult Black Skimmer in flight over the pond.

A sub-adult Black Skimmer in flight over the pond

Skimmers breed colonially, preferring to crowd in on beaches where they scrape shallow nests in the sand and lay broods of up to 4 eggs. After using alternate feet to kick sand aside, they sit in the depression and rotate to make a shallow, cone-shaped nest, averaging about 10 inches wide and one inch deep. Black Skimmers often nest with other birds such as gulls and terns, though within these multi-species gatherings, they tend to congregate together, forming dense, dark patches among their paler gray and white relatives. Black Skimmers are often quite vocal, especially in flight, where they communicate with low-pitched, nasal, calls and chuckles. Juveniles use a slightly different tone (more whiny!) while they follow their parents around begging for food. My kids did this too, so it’s not unique behavior! Even when not nesting, skimmers prefer to cluster together to roost, preferring beaches or islands to sit on. Skimmers can be very durable birds – the oldest recorded individual reached an age of 23 years in California.

Here in Orange County, California the largest nesting population of Black Skimmers is found at Bolsa Chica Ecological Reserve where their colony exceeds several thousand pairs. They can also easily be seen in Upper Newport Bay, at the San Joaquin Wildlife Sanctuary, and even well up the Santa Ana River into Anaheim, where they have a small breeding colony at Anaheim Shores. Skimmer numbers drop noticeably during the fall and winter seasons, so the best time to see them is late spring and summer, near coastal locations. So do yourself a favor and go check out these wonderful, bizarre and yet beautiful and graceful birds.

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