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Contact information
For information on Wisconsin's rare vertebrate animals, contact:
Rich Staffen
Conservation Biologist
For information on Wisconsin's rare invertebrates, contact:
Jay Watson
Conservation Biologist

Black Tern (Chlidonias niger)



Black Tern (Chlidonias niger), listed as Endangered, prefers large shallow marshes with abundant vegetation adjacent to open water. The required avoidance period is May 15 - July 31.

Conservation biologists are wrapping up a statewide Black Tern population survey to produce the first statewide population assessment since black terns were listed as State Endangered in 2014. To date, biologists have canoed, kayaked and bushwhacked to a total of 327 wetland sites in 49 counties and documented 115 colonies in 32 counties. Surveyors have recorded over 2500 breeding adults, most colonies ranging in size from 10 to 25 breeding adults and are somewhat surprised at the number of colonies. By 2020, they'll produce a comprehensive statewide report on black tern distribution, population size and habitats to inform conservation planning.

State status

Note: Black Tern (Chlidonias niger) was added to the Wisconsin E/T list on January 1, 2014 per administrative rule ER-27-11. Learn more

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Black Tern (Chlidonias niger). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.

Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.

Documented locations of Chlidonias niger in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusEND
Federal Status in WisconsinSOC
State RankS2B
Global RankG4G5
Tracked by NHIY

Species guidance

Identification: A gull like bird, but with long pointed wings and bill, that feeds by diving head first into the water. Adult black terns are mostly black with a dark gray back, wings and tail. Uniform pale gray underwings and a fairly short tail.

Habitat: Breeds in marshes, along sloughs, rivers, lakeshores, and impoundments, or in wet meadows, typically in sites with mixture of emergent vegetation and open water. Cattails, bulrushes, burreed, and/or phragmites commonly are present in nesting areas (Bent 1921, Cuthbert 1954, Goodwin 1960, Bailey 1977, Firstencel 1987, Novak 1990).

Rationale for Species Listing and Threats: Imperiled; most recent statewide surveys by Shealer and Matteson (2009, 2010) and FWS decadal Great Lakes region surveys (2009, 2010) indicate a significant declining population, with only 169 pairs documented in the entire Great Lakes basin, and with Black Terns notably absent as breeding birds in several locations. In Wisconsin, the 2010 statewide roadside transects represented a 36% decline in the statewide number of Black Terns since the previous year's survey and a 78% decline from the mean number of terns recorded in the 1980-82 surveys (860 compared to mean of 244 during 2009-2010). Decline may be due to loss of freshwater marsh habitat (including losses through invasion of exotic plants and due to drought), human disturbance of nesting sites, pesticide use, and problems along the migration route or in winter range (Muller et al. 1992, Novak 1992). Loss of breeding habitat has undoubtedly been a major contributing factor in the decline. Since European settlement, 54% of all wetlands in the United States have been lost (Tiner 1984). The loss of 4.75 million acres of palustrine emergent wetlands during the mid-1950s to mid-1970s has probably had an especially significant effect on populations. Similar losses of wetlands have been documented in Canada.

Diet: On the breeding grounds the black tern is primarily insectivorous, although small crustaceans, spiders and small fishes are also regular food items (McAtee and Beal 1912, Bent 1921). The diet may vary depending on habitat and food availability. Fishes may be an especially important food item at some sites in the northeast. In wetlands, food is captured in the air, at or just below the water surface, and from the surface of emergent vegetation (Goodwin 1960).

Clutch: One to five eggs may be laid, although the normal clutch is usually two or three (Bent 1921).

Incubation: Both sexes incubate (Goodwin 1960). Young are tended by both parents. Chicks are able to swim, walk and run by the time they are two days old (Goodwin 1960).

Nest: Nests are typically located in shallow water, close to open water or openings in stands of emergent vegetation.

Management Guidelines: The range of options available for the management of specific sites to benefit terns will vary with the degree to which water levels can be regulated at the site, the size and nature of the site, and the degree to which factors such as predation and disturbance are a problem at the site (Novak 1992).

  • Initiation of major lake or wetland ecosystem renovation projects where breeding habitat is declining is the most important management action. The highest priority Wisconsin sites in descending order are: 1. Rush Lake; 2. Green Bay west shore; 3. Winnebago Pool Lakes (including Lake Poygan); 4. Horicon Marsh Wildlife Area; and 5. Big Muskego Lake.
  • At managed state properties, it will be important to maintain long-term productivity of marshes by mimicking natural hydrologic regimes and adapting management techniques to localized conditions. Periodic drawdowns will benefit Black Terns and other species.
  • Control of carp and purple loosestrife is an ongoing concern.
  • At some sites, removal of Great Horned Owls (or mink) known to kill chicks may be essential to maintain or preserve colony productivity.
  • Use of artificial nesting platforms may benefit Black Terns and should be evaulated on a site-by-ste basis.
  • Black Terns may benefit from creation or restoration of marshes >20 ha or marshes >5 and <20 ha within a wetland complex. In large marshes, habitat patches >20 ha may be appropriate, with patches having a 50:50 interspersion of vegetation and water.
  • During the nesting season, water levels must remain stable. Water levels that encourage the stability of emergent patches must be a part of comprehensive management plans.



Black Tern

The Black Tern has declined over much of its North American range. Marshes in SE Wisconsin provide important breeding sites for this elegant bird.

Photo © Jack Bartholmai.

Black Tern

Photo © Jack Bartholmai.

Black Tern

Photo © Jack Bartholmai.

Black Tern

Black Tern on nest at Benzine's Pond.

Photo © Mike Mossman.

Black Tern

Black Tern nest on floating beam- 2 chicks, 1 egg. Nest #3 (p.F-54). Kakagon Sloughs.

Photo © Mike Mossman.

Wildlife Action Plan

Wisconsin Wildlife Action Plan graphic

Natural community (habitat) associations

The table below lists the natural communities that are associated with Black Tern. Only natural communities for which Black Tern is "high" (score=3) or "moderate" (score=2) associated are shown. See the key to association scores for complete definitions. Please see the Wildlife Action Plan to learn how this information was developed.

Ecological landscape associations

The table below lists the ecological landscape association scores for Black Tern. The scores correspond to the map (3=High, 2=Moderate, 1=Low, 0=None). For more information, please see the Wildlife Action Plan.

This map shows the probability of Black Tern occurring in each of Wisconsin's Ecological Landscapes.  Actual scores can be found in the table to the left.

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Landscape-Community combinations of highest ecological priority*

Ecological priorities are the combinations of natural communities and ecological landscapes that provide Wisconsin's best opportunities to conserve important habitats for a given Species of Greatest Conservation Need. The 10 highest scoring combinations are considered ecological priorities and are listed below. More than 10 combinations are listed if multiple combinations tied for 10th place. For more information, please see the Wildlife Action Plan.

* Ecological priority score is a relative measure that is not meant for comparison between species. This score does not consider socio-economical factors that may dictate protection and/or management priorities differently than those determined solely by ecological analysis. Further, a low ecological priority score does not imply that management or preservation should not occur on a site if there are important reasons for doing so locally.

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Issues/threats and conservation actions

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Threats/issues and conservations actions for rare animals

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Last revised: Thursday, December 22, 2022