Where does the Forster's Tern live?
Sterna forsteri
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Open the appThe Forster's Tern lives in specific habitats and regions. Knowing where, and when, to look improves your chances of a successful sighting.
Biomes
Coastal wetlands, estuaries, salt marshes, freshwater marshes, lakes, rivers, and coastal beaches.
Geographic range
Breeds across North America, primarily in the interior and along the Atlantic and Gulf Coasts. Winters along the Pacific, Atlantic, and Gulf Coasts of the United States, Mexico, and Central America.
Preferred environments
Shallow coastal bays, estuaries, salt marshes, and large freshwater marshes with emergent vegetation for nesting. During migration and winter, they favor sheltered coastal waters, lagoons, and tidal flats.
Elevation range
Typically found from sea level up to a few hundred meters, primarily in lowland wetland habitats.
Where to look
Estuaries and Bays
In the San Francisco Bay Area, look for Forster's Terns in estuaries, tidal flats, and shallow bay waters. They are common in areas like San Francisco Bay, San Pablo Bay, and Suisun Bay.
Salt Marshes
Coastal salt marshes, particularly those with open water and mudflats, are prime foraging and roosting areas. Examples include the Don Edwards San Francisco Bay National Wildlife Refuge.
Coastal Lagoons and Beaches
Sheltered coastal lagoons and sandy beaches along the Pacific coast of California will host wintering and migratory individuals.
Piers and Docks
They often perch on pilings, docks, and buoys in harbors and marinas, including those around San Francisco.
Field tips
- Scan Open Water. Look for them actively plunge-diving for fish over shallow water or hovering gracefully before a dive.
- Check Roosting Flocks. Examine flocks of terns roosting on mudflats, sandbars, or jetties. Look for the distinctive head patterns (black cap in summer, eye-patch in winter) and bill coloration.
- Listen for Calls. Their harsh calls are often the first indication of their presence, especially when they are disturbed or interacting.
- Seasonal Timing (San Francisco Bay Area). Forster's Terns are present year-round in the San Francisco Bay Area, but their numbers swell significantly during fall and spring migration, and they are abundant as winter residents. Breeding occurs further inland or south, but non-breeding individuals may be seen locally during summer.
- Binoculars and Scope. Good optics are essential for distinguishing field marks, especially the subtle differences from similar tern species.
Migration
Strongly migratory. Northern populations migrate south for the winter, while some southern populations may be resident or undertake shorter movements. They migrate along coastlines and major river systems. In the San Francisco Bay Area, they are primarily a wintering and migratory species, with some non-breeding individuals present year-round.
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