Common Tern - Sterna hirundo
In breeding plumage, the Common Tern has an orange-red bill tipped in black and orange-red legs. The back, body, and wings are a silvery-gray with blackish primaries on the wingtips, evident during flight. The nape and cap are black and extend low enough on the head to contain the black eye before abruptly stopping at the white of the cheek and neck. The outer tail feathers on the forked tail are dusky. In non-breeding plumage the bill and legs lose their red coloration and are black. The cap no longer covers the forehead, leaving a white patch nearly to the top of the head (Sibley 2000).
The vocalization is described as numerous, varied, and of sharp, distinctive, and somewhat irritable timbre (Nisbet 2002). The most common call, the advertising call, is described as a down-slurring "keeyuur"
or an up-slurred "keeuri"
in addition to the "kip"
call that is expressed during flock feeding, or during take-off and landing (Sibley 2000, Nisbet 2002).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
Distinguishable from Forster's Tern (S. forsteri) by the Forster's Tern's whiter underparts, lighter primaries, lighter back coloration (and, hence, less difference in color between back and tail), and greater amount of black on a bill that is more orange than red-orange (Sibley 2000, Nisbet 2002).
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
SUMMER (Feb 16 - Dec 14)
Direct Evidence of Breeding
Indirect Evidence of Breeding
No Evidence of Breeding
WINTER (Dec 15 - Feb 15)
Not Regularly Observed
(Observations spanning multiple months or years are excluded from time charts)
Congregations of birds on the wintering grounds in April, and sometimes into May, suggest that spring migration occurs rapidly (Nisbet 2002). The earliest migration date for Common Tern in Montana is in April, but the most concentrated arrival of birds occurs in May. Breeding has been recorded in May, June, and July, with fall departure beginning in late August and continuing into September (Montana Bird Distribution Committee 2012). The extreme migration dates for the Common Tern are April 23, 1993 at Freezout Lake and October 3, 1960 in Madison County (Reichel 1996). Normal migration periods in Bozeman are May 9 to 25 and September 5 to 25, with peaks on May 9 and September 15. The normal arrival date in Fort Peck is April 30, and in Billings, May 9 (Skaar et al. 1985).
Nesting in Montana generally occurs on sparsely vegetated islands in large bodies of water, such as Medicine Lake and Bowdoin National Wildlife Refuge. Nest substrate at these locations includes sparsely sandy, pebbly, or stony substrate, surrounded by matted or sparsely scattered vegetation (Casey 2000, Nisbet 2002). A study in the Lewistown District of the Bureau of Land Management documented that the Common Tern selected sites larger than 30 acres, with emergent vegetation covering more than 25% of the shoreline on all but one of the eight sites studied (Feigley 1997). All nesting occurred on islands (Feigley 1997).
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: mtnhp.org/requests
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
Food habits of Common Terns have not been closely studied in Montana. In other breeding locations in their range, studies have shown the diet consists mainly of small fishes (sometimes also crustaceans and insects) obtained at the surface of the water by diving from the air. Common Terns are susceptible (especially females just prior to laying) to poisoning from dinoflagellate toxin accumulated in fishes (Nisbet 1983). A pair may defend feeding territory away from the nest, especially prior to incubation (Ehrlich et al. 1992).
No ecological data is available for this species in the state. However, in Massachusetts, loss of eggs and chicks was attributed to nocturnal desertion of nests by adults in response to predation by the Great Horned Owl (Nisbet and Welton 1984). The presence of American Mink can reduce reproductive success (Burness and Morris 1993). Mammalian predation generally eliminates nesting colonies, limiting continuous successful nesting to islands (Nisbet 2002).
During the nonbreeding season, Common Terns may be found singly or in small, loose groups, and sometimes in large flocks in migration (Stiles and Skutch 2003). Staging flocks of up to 10,000 individuals have been reported in the Great Lakes region (Nisbet 2002).
The majority of breeding activity in Montana occurs in the northern portion of the plains on islands within large lakes or reservoirs. Based upon known distribution and recorded observations, up to 50 breeding occurrences for this species are expected in the state (Reichel 1996). The areas with the highest recorded numbers of nesting Common Terns are Bowdoin and Medicine Lake National Wildlife Refuges. Limited numbers of nesting terns have been reported at Nelson Reservoir, Benton Lake National Wildlife Refuge, and Freezout Lake (Montana Bird Distribution Committee 2012). Behavior suggesting breeding has been reported at other bodies of water within the prairie portion of the state including Lower Wild Horse, Mud Lake, Ward Reservoir, Two Forks Reservoir, Lake Elwell, Tiber Reservoir, and Halfway Lake in the Sands Waterfowl Production Area. Most colonies are under 50, with sizes ranging from 2 to 236 (Reichel 1996). Although rare, breeding has been recorded west of the Continental Divide; one report exists for the Kalispell area and another near Polson (Montana Bird Distribution Committee 2012).
In general, the Common Tern is a colonial nesting species and may be found in colonies of tens or hundreds of pairs, though they may range from a few (rarely singly) to several thousand (Nisbet 2002). Their subelliptical eggs are smooth, non-glossy, cream, buff, or medium-brown with fine marks, blotches, specks or irregular lines of brown, black, or gray and 42x30 mm (Baicich and Harrison 2005, Nisbet 2002). Egg-laying usually takes place May to July, and clutch size is 2 to 3. Incubation, performed mainly by the female, lasts 21 to 27 days. The nest may be a simple scrape in the soil or sand and may be lined with grass, pebbles, or small sticks. Both sexes tend young, which may leave the nest after 3 days, returning only to brood, and first fly at about 4 weeks. The species may produce two clutches in one season, but the second brood rarely fledges. In New York, the breeding season was timed to overlap with a seasonal increase in food abundance, but food availability began to decline before the period of peak demand for food by chicks (Safina and Burger 1988). In a two-year study, fish abundance affected reproductive performance (Safina et al. 1988).
Management recommendations in Montana include providing adequate water levels to protect nesting islands from mammalian predators, managing water to better mimic seasonal fluctuations to prevent flooding of nesting sites, and minimizing human disturbance at nesting colonies during the nesting season (Casey 2000). None of these recommendations are currently in place specifically for the protection of Common Tern, although more natural water regimes are considered in the management plans for several dammed rivers in the state.
- Literature Cited AboveLegend: View Online Publication
- Baicich, P.J. and C.J.O. Harrison. 2005. A guide to the nests, eggs and nestlings of North American birds. Second edition. Academic Press, New York.
- Burness, G. P. and R. D. Morris. 1993. Direct and indirect consequences of mink presence in a common tern colony. Condor 95:708-711.
- Casey, D. 2000. Partners in Flight Draft Bird Conservation Plan Montana. Version 1.0. 287 pp.
- Erhlich, P.R., D.S. Doblin, and D. Wheye. 1992. Birds in jeopardy: the imperiled and extinct birds of the United States and Canada, including Hawaii and Puerto Rico. Stanford University Press, Stanford, California.
- Marks, J.S., P. Hendricks, and D. Casey. 2016. Birds of Montana. Arrington, VA. Buteo Books. 659 pages.
- Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map.
- Nisbet, I. C. T. 1983. Paralytic shellfish poisoning: effects on breeding terns. Condor 85:338-345.
- Nisbet, I. C. T. and M. J. Welton. 1984. Seasonal variations in breeding success of common terns: consequences of predation. Condor 86:53-60.
- Reichel, J. D. 1996. Preliminary colonial nesting bird survey on the Bureau of Land Management Lewistown District: 1995. Unpublished report, U.S. Bureau of Land Management, Lewistown, Montana.
- Safina, C. and J. Burger. 1988. Prey dynamics and the breeding phenology of common terns (Sterna hirundo). Auk 105:720-726.
- Safina, C., J. Burger, M. Gochfeld, and R. H. Wagner. 1988. Evidence for prey limitation of common and roseate tern reproduction. Condor 90:852-859.
- Sibley, D.A. 2000. The Sibley guide to birds. National Audubon Society and Alfred A. Knopf, Inc., New York, NY. 544 pp.
- Skaar, P. D., D. L. Flath, and L. S. Thompson. 1985. Montana bird distribution. Montana Academy of Sciences Monograph 3(44): ii-69.
- Stiles, F.G. and A.F. Skutch. 2003. A guide to the birds of Costa Rica. Comstock Publishing Associates, Cornell University Press, Ithaca. 511 pp.
- Additional ReferencesLegend: View Online Publication
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- American Ornithologists Union. 1983. Checklist of North American birds, 6th Edition. 877 PP.
- American Ornithologists’ Union [AOU]. 1998. Check-list of North American birds, 7th edition. American Ornithologists’ Union, Washington, D.C. 829 p.
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- Carlsen, T. and R. Northrup. 1992. Canyon Ferry Wildlife Management Area Final Draft Management Plan. March 1992.
- Casey, D. 2000. Partners in Flight Bird Conservation Plan Montana Version 1.0. Montana Partners in Flight. Kalispell, Montana.
- Casey, D. 2004. Coordinated bird monitoring in Montana - special habitat/species monitoring: wetlands and colonial nesters. Montana Bird Conservation Partnership and University of Montana. pp 12 plus appendix.
- Confluence Consulting Inc. 2011. Montana Department of Transportation Wetland Mitigation Monitoring Reports (various sites). MDT Helena, MT.
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- Feigley, H. P. 1997. Colonial nesting bird survey on the Bureau of Land Management Lewistown District: 1996. Unpublished report, U.S. Bureau of Land Management, Lewistown, Montana.
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- Hand, R.L. 1969. A distributional checklist of the birds of western Montana. Unpublished. Available at Mansfield Library, University of Montana, Missoula.
- Hays, R., R.L. Eng, and C.V. Davis (preparers). 1984. A list of Montana birds. Helena, MT: MT Dept. of Fish, Wildlife & Parks.
- Hendricks, P., S. Lenard, C. Currier, and J. Carlson. 2007. Grassland bird surveys in north Valley County, Montana: 2001-2006. Report to the Bureau of Land Management, Glasgow Field Office. Montana Natural Heritage Program, Helena, Montana. 19 pp. plus appendices.
- Johnsgard, P.A. 1992. Birds of the Rocky Mountains with particular reference to national parks in the northern Rocky Mountain region. Lincoln: University of Nebraska Press. xi + 504 pp.
- Joslin, Gayle, and Heidi B. Youmans. 1999. Effects of recreation on Rocky Mountain wildlife: a review for Montana. [Montana]: Montana Chapter of the Wildlife Society.
- Lenard, S. 2006. Birds of Blaine County, Riparian Point Count Surveys 2005. Report to the Bureau of LandManagement, Havre Field Station, Havre, Montana. Montana Natural Heritage Program, Helena, MT. 16pp.plus appendices.
- Lenard, S., Compiler. 2005. Surveys for Animal Species of Concern in Sage and Grassland Landscapes in Montana. An unpublished report to the Montana Department of Fish, Wildlife & Parks, State Wildlife Grants Program. Montana Natural Heritage Program, Helena, Montana. 63pp.
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- Lokemoen, J.T. 1993. Increasing waterfowl nesting success on islands and peninsulas. Ch. 13.2.11 In: Waterfowl Management Handbook. Fish and Wildlife Service Leaflet. 7 p.
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- Nisbet, I.C. 2002. Common Tern (Sterna hirundo). Species Account Number 618. The Birds of North America Online (A. Poole, Ed.). Ithaca, NY: Cornell Laboratory of Ornithology; Retrieved 3/25/2008 from The Birds of North America Online database
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