Chlidonias hybrida (Pallas, 1811)

General Appearance

This species, the whiskered tern, has a size, black cap, strong bill, and more active flight that recall common or Arctic terns, but its short, forked-looking tail and dark grey breeding plumage on both upper and lower body are typical characteristics of marsh terns.

Bill Morphology

For the bill, males have bills measuring 29–34 mm, while females have stubbier bills measuring 25–27 mm, all with a pronounced gonys.

Summer Adult Plumage

Summer adults have white cheeks, red legs, and a red bill.

Juvenile and Winter Adult Crown Features

Juveniles have crowns flecked with white and a more uniformly blackish hindcrown; winter adults also have hindcrowns flecked with white.

Head Markings

The black ear-coverts connect to the black of the hindcrown, and the space above this connection is mottled with white, creating the appearance of a C-shaped black band.

Neck and Nape Coloration

The sides of the neck are white, and this white color sometimes extends all the way across the nape.

The neck collar is less sharply defined.

Rump Coloration

The rump is pale grey year-round.

Juvenile Mantle and Back Pattern

Juveniles have a variegated pattern on the mantle.

Their back and scapular feathers are dark brown, with prominent broad buff edgings and often subterminal buff bars or buff centers.

Juvenile Plumage Molt

Usually, an admixture of new gray feathers, especially on the mantle, appears quite early in the fall.

Adult Mantle Coloration

Adult whiskered terns have a silvery-grey mantle.

Species Call

The species' characteristic call is a krekk.

Winter Adult Plumage

In winter, the forehead turns white and the body plumage becomes much paler grey.

Juvenile Overall Plumage

Juvenile whiskered terns have a ginger scaly back, and otherwise closely resemble winter adults.

First Winter Plumage

First winter plumage is intermediate between juvenile and adult winter plumage, with patchy ginger coloring on the back.

Diet

Whiskered terns feed on small fish, amphibians, insects, and crustaceans.