Terns

Terns are graceful, streamlined water birds that vary in appearance depending on age and season. In general, adults have:

• A whitish body with a black "cap" on the head during breeding season.
• A deeply forked tail.
• A pointed bill that is usually aimed down toward the water when the tern is flying.

What species of terns live in the Bay watershed?

Five species of terns can be found in the Bay watershed: the Caspian tern, the royal tern, the least tern, the common tern and Forster's tern.

The Caspian tern, Sterna caspia, grows to a maximum of 23 inches and has:

• Black legs.
• A reddish-orange bill with black near the tip.
• A tail that is not as deeply forked as other tern species.
• A black "cap" during breeding season.

The royal tern, Sterna maxima, is slightly smaller and slimmer than the Caspian tern and has:

• An orange bill.
• A black crest of feathers that form a crown on its head.
• A white forehead that turns black during breeding season.

The least tern, Sterna antillarum, is the smallest Bay tern, growing to a maximum of 9 inches. It has:

• Yellow legs.
• A gray back and wings.
• A light yellowish-orange bill with a black tip.
• A black "cap" and white forehead during breeding season.

The common tern, Sterna hirundo, grows to a maximum of about 16 inches and has:

• Reddish-orange legs.
• A black-tipped orange bill.
• A black "cap" during breeding season.
• A black nape and white forehead in winter.
• Dusky to slate gray wing tips.
• A white tail.

Forster's tern, Sterna forsteri, looks very similar to the common tern during breeding season, but has a gray tail and frosty gray wingtips. In winter it has a white head with a black “mask” through the eyes and ears.

While in flight:

• Caspian terns are mostly white with dark wingtips on the underside.
• Royal terns are nearly all white underneath.
• Least terns have lighter underwings with a black edge near the tip. Their wingbeats are quicker than other terns.
• Common and Forster's terns have a slight gray wash on their underparts. Common terns also have dark wingtips.

Where do terns live?

• Caspian terns are found throughout the Bay region and often range inland.
• Royal terns live along the Bay's shoreline from Tilghman Island south.
• Least terns are common throughout the Bay in spring and summer. They are often seen on buoys and pilings. In autumn they migrate southward for the winter.
• Common and Forster's terns are found on the deeper, open waters of the Bay.

What do terns eat?

Terns hunt by hovering over the water to find their prey, then diving headfirst into the water to catch it. This habit has led to the nickname "face smashers."

• Caspian, royal, common and Forster's terns feed on fish and invertebrates, such as crabs, squids and shrimps.
• Least terns feed on fish, insects and small crustaceans. They tend to hover longer than other terns while hunting and will also retrieve their prey by skimming the surface of the water.

What do terns sound like?

• Caspian terns: A hoarse, low kraa-uh or karr and multiple kaks.
• Royal terns: A keer that is higher than the Caspian's, as well as a kaak or kak.
• Least terns: Multiple sharp kits; a harsh, squealing zree-eek or zeek; and quick kitti-kitti-kittis.
• Common terns: A slow kee-arr with a downward inflection, as well as kik-kik-kiks and rapid kirri-kirris.
• Forster's terns: A sharp, nasal za-a-ap and kyarr.

Where do terns nest and breed?

Terns are colonial nesters on beaches, marshes and other areas along the Atlantic coast.

Caspian terns breed in small colonies, mostly on sand, shell or gravel beaches and sometimes in marshes.

• Females lay two or three pinkish-buff eggs in nests formed in beach rubble, rock crevices or small depressions in the ground.
• Caspian tern continue to feed their young five to seven months after they are able to fly -- longer than any other tern species.

Royal terns breed in large, crowded colonies on isolated sand bars and beaches along the mid-Atlantic coast, sometimes including Fisherman Island near the mouth of the Bay.

• Females lay one buff-white egg in a simple nest scraped into the sand.
• Royal tern fledglings group together in a creche and the parents continue to feed their own chick, even though the young are able to feed themselves.

Least terns breed on the Bay region's sand bars and beaches from June to mid-July. They begin breeding in their second year.

• Females lay one to three olive-buff and brown eggs in shallow nests.
• Eggs hatch in about three weeks and the young fledge in less than a month.
• Immature least terns are mottled with a dark bill, legs and forewings.

Common terns nest on islands, sand bars, beaches, and stony or gravelly areas. In the Bay region, several nesting sites exist from Fisherman Island to Eastern Bay near Kent Island, Maryland.

• Females lay two to three olive brown-buff eggs in a shallow nest scraped out of the sand. The eggs hatch in about two weeks.
• Common terns are extremely aggressive toward potential intruders to their nesting grounds.
• Immature common terns have a dark shoulder bar, a blackish bill and an incomplete black cap.

Forster's terns build shallow nests among vegetation in salt marshes.

• Females lay three buff-brown eggs that hatch in about two weeks.
• Immature Forster's terns have a black "mask" through the eye and ear that does not extend to the nape.

Other facts about terns:

• The Caspian tern is the largest tern in North America, while the least tern is the smallest.
• Terns are frequently confused with gulls. Terns can be identified by their forked tails and pointed bills and wings. Also, terns fly with their bills pointed downward and plunge headfirst into the water to retrieve their prey, while gulls fly with their bills straight ahead and skim the water's surface to catch prey.
• Because their coloration varies depending on age and season, specific species of terns can be very hard to accurately identify.