Forster's Tern

The Forster's is the only tern in the Rockies that has an exclusively North American breeding distribution, but it bears the name of a man who never visited this continent. Johann Forster, who lived and worked in England, examined several tern specimens from the Hudson Bay region. He suggested that there was an additional species aside from the very similar Common Tern. Thomas Nuttall agreed, and in 1832 he named the species the Forster's Tern in his classic Manual of Ornithology. Forster's greatest naturalist experience may have been on board the famous Cook voyage to the south Pacific. On that trip, both his natural history observations and his quarrels with the captain are legendary. Terns are not named for their aerial maneuverability: 'tern' comes from their Old Norse name therna.

Sterna forsteri I.D.: Sexes similar. Breeding: black cap and nape; thin, orange, black-tipped bill; light gray back; red legs; white underparts; white rump; mostly gray tail. Non-breeding: lacks the black cap; black mask over the eyes. In flight: shallowly forked tail; long, pointed wings. Size: L 14-16 in. (36-41 cm); W 31 in. (79 cm). Range: rare migrant and uncommon summer visitor in the southern U.S. Rockies; rare migrant and summer visitor in the Canadian Rockies. Habitat: Summer: cattail marshes and backwaters. In migration: lakes. Nesting: typically on the Great Plains and in the Northwest; occasionally colonial; atop floating vegetation in freshwater marshes, occasionally on muskrat lodges or on a grebe's nest; both parents incubate the eggs and raise the young. Feeding: hovers above the water and plunges headfirst after small fish and aquatic invertebrates. Voice: call when flying is a nasal, short keer keer; also a grating tzaap. Similar Species: Common Tern: darker red bill and legs; mostly white tail; dark-tipped primaries; call is longer and drawn out. Caspian Tern: much larger; all-red bill.