Least Tern courtship. Photo by Peter Vankevich

By Peter Vankevich
I have sometimes mused how I would end my Birds of Ocracoke profile series with: Last, but not least, is the Least Tern.

Sometimes called a sea swallow, the Least Tern (Sternula antillarum) has a graceful, fast, buoyant flight pattern with rapid wing beats.

Careful observers will notice they are capable of suddenly putting on the skids, hovering above water, then quickly plunging to grab a small fish, their prey of choice.

Their diminutive size, the smallest tern in North America, makes them fairly easy to identify from the beach, even without binoculars as many make their way back and forth from South Point where the majority of them nest in a large colony that includes Common Terns, Gull-billed Terns and Black Skimmers.

Closer views reveal the Least Tern’s bright yellow bill, sometimes with a black tip, a black cap, white forehead, a black eyeline, and orange legs.

Do not expect to see their nonbreeding plumage here as they depart in late summer or early fall for Central America, South America and parts of the Caribbean.

Least Tern. Photo by Peter Vankevich

In winter, their heads are white, and they have a black eye stripe that goes toward the back of the head and black bills.

Tern identification in August on Ocracoke can be tricky since the fledged birds have duller plumages and their bills and leg colors can differ from the adults. Also, the adults may be going through their molt and their black caps begin to disappear.

But it is the small size of the Least Tern that makes it easily identified.

Their calls are a sharp Ki-dik and an alarm call described as wreep.

Like American Oystercatchers, Least Terns take a minimalist approach to constructing their nests, which is just a shallow scrape in sand or soil with some small bits of shell or vegetation added and lay two or three eggs.
Both adults incubate and care for the young, which hatch in about 30 days. Precocial downy chicks hatch with open eyes and are ready to fly after 20 days.

Feisty is a description of their character as they will drive off would-be predators attempting to eat their eggs or hatchlings, including ghost crabs, one of the most aggressive predators of both bird and turtle hatchlings on Ocracoke Island.

Least Terns breed on the East Coast from southern Maine down to southern Florida including the shores of the Chesapeake Bay.

They are rarely seen inland in North Carolina, so it might be a surprise for some to see that a subspecies, Sternula antillarum athalassos, can be found along rivers in the Mississippi and Missouri Valleys west to the Great Plains of Montana and Colorado. There is also a California subspecies, Sternula antillarum browni.

Least Terns prefer to nest on open beaches like South Point and vegetation-free islands. However, some, including those on Emerald Isle, have adapted to human disturbance and habitat destruction by nesting on gravel roof tops.

A Least Tern fends off a ghost crab. Photo by Ben Ranelli/NPS

Roof tops are not ideal nest sites because in hot weather the tar can become stuck in the chick’s down or burn their feet.
Because of their preferred low-lying nest sites, these terns are susceptible to tropical storms and overwash as was the case this spring when all of the nests on the South Point were wiped out.

The good news is that Least Terns are resilient as they will attempt to re-nest after such calamities. By June 22, there were approximately 100 nests on South Point and a small colony on the beach at the north end of Ocracoke.

Best time to see: Late spring, summer, early fall. Absent in winter.
Where: Resting on the beach and in flight over the water, Srpinger’s Point, and seen from ferries
Listen:The Macaulay Library at the Cornell Lab of Ornithology has a variety of Osprey recordings. Click here.

Like many species with handsome feathers, Least Terns came to the verge of extinction for their prized small feathers that were the fashion for ladies’ hats.

Apparently, their eggs were prized as well. In a 1913 news story in the South Carolina newspaper, “The State,” James Henry Rice warned that this vanishing species would soon join the Passenger Pigeon and the Great Auk to extinction unless strict measures were taken to protect it.

He noted that Least Tern eggs were sold in Charleston by the bushel. Since they lay only two eggs, it is not hard to see why they were on the brink.

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