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Forster's Tern

Sterna forsteri

Length: 15 inches Wingspan: 30 inches Seasonality: Summer / Migrant
ID Keys: Black cap and nape, deeply forked tail, white underparts, pale gray upperparts, orange-red bill, legs, and feet.

Forster's Tern - Sterna forsteriForster's Terns are generally the most common of the black-capped, gray-backed, white bodied terns found in the state.  Very similar to the Common Tern, the Forster's Tern is also the more common breeder in the state, generally being found around freshwater marshes, and often nesting on the top of muskrat houses.  Differentiating between Forster's Terns and Common Terns can be difficult unless seen well (see identification tips down below). Forster's Terns may also sometimes be seen with Black Terns, with mixed nesting colonies of the two species relatively common.

Habitat:

In summer, primarily large freshwater marshes on the interior of the country, or salt marshes along the coasts. In winter, many aquatic habitats along the coasts.

Diet:

Primarily fish, but will also eat insects, small crustaceans and mollusks, frogs, and tadpoles.

Behavior:

Forages by flying slowing over water or hovering, dipping down to snag sighted fish below the surface.  They will also sometimes capture flying insects in mid-air.

Nesting:

June and July in South Dakota. The nest of a Forster's Tern is typically placed on the ground in the cover of vegetation, including dead marshland vegetation, nearby meadow grasses, or even on the top of a Muskrat lodge. The nest consists of a small platform of grasses, lined with finer vegetative material. The female lays between 1 and 3 eggs, with both sexes helping to incubate them. The young hatch after about 24 days.

Song:

A variety of vocalizations, including a sharp kyeer and a grating grreee.

1Click here to hear the sharp kyeer calls of a Forster's Tern

2Click here to hear the agitated grating greeee calls of a Forster's Tern

Migration:

Summers in scattered locations throughout the U.S. (including parts of northeastern South Dakota) and southern Canada.  Winters along U.S. coastlines and points south, but is generally not as much of a long-distance migrant as its close relatives.

Interactive eBird Map:

Click here to access an interactive eBird map of Forster's Tern sightings

Similar Species:

 Similar in appearance to multiple other tern species, with one in particular potentially causing an identification concern in South Dakota

Conservation Status:

Has declined in portions of its range, probably due to habitat loss. However, overall populations are stable or may actually be increasing, and they are found across a very broad geographic range. The IUCN considers the Forster's Tern to be a species of "Least Concern".

Further Information:

1) Whatbird - Forster's Tern

2) BirdWeb - Forster's Tern

3) Audubon Guide - Forster's Tern

Photo Information:

June 23rd, 2005 - Assateague Island in Virginia - Terry Sohl

Additional Photos:

Click on the image chips or text links below for additional, higher-resolution Forster's Tern photos.

Audio File Credits:

1David Darrell-Lambert. Recorded in Essex County, Ontario on May 14th, 2019. Original file and recording from xeno-canto.

2Paul Marvin. Recorded in Barton County, Kansas on May 24th, 2015. Original file and recording from xeno-canto.

Click on the map below for a higher-resolution view
Forster's Tern - Range Map
South Dakota Status: Common migrant and summer resident in the eastern part of the state and in the northern Sand Hills on the southern edge of the state.  Uncommon migrant and summer visitor elsewhere in the state.

Additional Forster's Tern Photos
Click for a higher-resolution version of these photos
 Forster's Tern 1 - Sterna forsteriForster's Tern 2 - Sterna forsteriForster's Tern 3 - Sterna forsteriForster's Tern 4 - Sterna forsteriForster's Tern 5 - Sterna forsteriForster's Tern 6 - Sterna forsteriForster's Tern 7 - Sterna forsteriForster's Tern 8 - Sterna forsteriForster's Tern 9 - Sterna forsteriForster's Tern 10 - Sterna forsteriForster's Tern 11 - Sterna forsteriForster's Tern 12 - Sterna forsteriForster's Tern 13 - Sterna forsteriForster's Tern 14 - Sterna forsteriForster's Tern 15 - Sterna forsteriForster's Tern 16 - Sterna forsteriForster's Tern 17 - Sterna forsteriForster's Tern 18 - Sterna forsteriForster's Tern 19 - Sterna forsteriForster's Tern 20 - Sterna forsteri