Forster's Tern (Sterna forsteri) lives in marine coastal across North America. It feeds on fish and crustaceans. Its conservation status is Least Concern.
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A Forster's tern can weigh as little as 130 g or as much as 190 g, yet its wingspan stretches 78-80 cm. This compact power-to-weight ratio lets it plunge-dive straight into water, a hunting style that differs from the "stepped-hover" of Arctic terns. By diving head-first with wings partially folded, the bird can snatch fish before the prey even knows it's there, giving the tern a stealthy edge in murky marshes where prey hide near the water's edge.
A single Forster's tern colony can swell from a handful of pairs to a thousand individuals, all packed into a marshy island or floating raft of vegetation. When nesting sites run short, the birds will even build nests on sand, gravel or mud, lining them with driftwood, shells or dried fish. This flexibility makes nests vulnerable to storms that can wash away eggs, explaining why weather is the leading cause of nest failure.
Both male and female Forster's terns share incubation duties, with males guarding the nest by day and females taking the night shift. The eggs hatch after 24-25 days, and the chicks lose their egg-teeth within three to five days. By day four the young can leave the nest, though they remain dependent on parents for food until they fledge at 28 days.
When a predator approaches a Forster's tern nest, the entire colony erupts in a coordinated mob: adults dive toward the threat, emitting loud calls. This aggressive defense peaks just before and during hatching, and neighboring species such as yellow-headed blackbirds and western grebes recognize the tern's alarm call, gaining protection themselves. The collective aggression dramatically lowers predation rates on eggs and chicks, showing how communal behavior can boost individual survival.
Forster's terns breed across North America, nesting in freshwater, brackish, or saltwater marshes from the Great Lakes to the Pacific coast. Their winter range stretches to the southern United States, Mexico, the Caribbean, and even occasional sightings in western Europe. Rising carp populations that damage marsh vegetation and artificial noise from boats still threaten nesting sites, highlighting the need for wetland protection.
Sources
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As the sun rises over the marshy wetlands, the Forster's Tern awakens, its sleek, grey form unfolding like a ghostly apparition, its wings beating with a mesmerizing rhythm as it takes to the skies. With an effortless glide, it dances on the breeze, its sharp, black-tipped bill slicing through the air as it pursues the tiny fish and crustaceans that dwell in the shallow waters below. In its fluid, aerial ballet, the Forster's Tern embodies the very essence of coastal elegance, a symphony of movement and light that is at once both captivating and serene.
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