Plants and Animals
Sterna hirundo Common tern
The slender body, long pointed wings and deeply forked tail are key characteristics of the Common tern. Their typical call is a drawled "kee-arr". Their 31 inch (78.7 cm) average wingspan distinguishes them from the Caspian tern whose wingspan averages 54 inches (137 cm). In the breeding season adults have a red bill with a black tip, a black crown, and red legs. Although it is easily confused with the Forster's tern, the Common tern has a gray body, darker wing tips, a higher pitched call, and a redder bill.
Status and Rank
US Status: No Status/Not Listed
State Status: T - Threatened (legally protected)
Global Rank: G5 - Secure
State Rank: S2 - Imperiled
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Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Common terns typically nest on islands to avoid many terrestrial predators.
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Human factors that limit Common tern populations include island and beach development, use of off-road vehicles on beaches, and the release of chemical contaminants into the environment. Using fire to expose the ground surface, in areas succeeding to closed vegetation, has been demonstrated to be very helpful to Common terns. Control of competitors and predators may be crucial in maintaining common tern populations, although restricting only one competitor or predator is usually not adequate to increase fledgling success. Intensive programs to control all predators impacting a population as well as reducing disturbances by humans may be needed Recreational boating should be controlled within close proximity to nesting colonies during the nesting season.
Migration from third week of April to third week of May
Nesting from second week of May to first week of July
Migration from third week of August to fourth week of October
Common terns may be surveyed by searching suitable nesting or foraging habitat by foot, boat, or aircraft. Particular attention should be paid to adults observed carrying food in their bill during the nesting period because they may be returning to the nesting area to feed young.
Survey Period: From first week of May to fourth week of July
Time of Day: Daytime
- Bibby, C.J., N.D. Burgess, and D.A. Hill. 1992. Bird Census Techniques. Academic Press, New York.
- Evers, D.C. 1994. Endangered and Threatened Wildlife of Michigan. The University of Michigan Press, Ann Arbor. 412pp.
- Hyde, D.A. 1997. Special Animal Abstract for Sterna hirundo (Common tern). Michigan Natural Features Inventory, Lansing, MI. 3pp.