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Chlidonias niger

(Black Tern)

Overview:

Conservation Status

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Population Analysis

  • For the 56,576 species in the Class Aves (Birds), we average 371.87 observations each in our database; for the Black Tern, we have 3,288 observations. Compared to other species in this Class, this species is somewhat common.
  • A two-sample t-test can be used to determine whether the trend in observations of the Black Tern is the same as the trend in observations of Aves. Is this species just as common, as a proportion of all observations, as it once was? The answer is no, changes in observation rate of this species significantly differ from changes in observation rate of its Class. (t=6.132, p<0.001)
  • How do observation rates of the Black Tern differ from those of Aves? To answer this, we examined the percentage of observerations for Aves that were observations of the Black Tern each year. We then correlated this percentage with observation year. If observations of the Black Tern are becoming more common relative to other species of Aves, the correlation should be positive, but if it is becoming less common, the correlation should be negative. In fact, the correlation is negative (r=-.23), with a negative slope (m = -.001), suggesting that the Black Tern may be in decline relative to other species of Aves. This correlation is statistically significant. (F = 40.29, p<.05)
  • The scatter chart to the right shows the percentage of all observations for Aves each year that were observations of the Black Tern.

History:

  • 1988-Lower Risk/least concern (BirdLife International 2004)
  • 1994-Lower Risk/least concern (BirdLife International 2004)
  • 2000-Lower Risk/least concern (BirdLife International 2000)

Justification

This species has a large range, with an estimated global extent of occurrence of 10,000,000 km². It has a large global population estimated to be 450,000¿1,300,000 individuals (Wetlands International 2002). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.

Taxonomy

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  • Domain: Eukaryota Whittaker & Margulis,1978 - eukaryotes
    • Kingdom: Animalia Linnaeus, 1758 - Linnaeus, 1758 - animals

Unambiguous Synonyms:

  1. Chilidonias niger (Linnaeus, 1758)
  2. Chilidonias niger subsp. surinamensis (Gmelin, 1789)

Notes:

Name Status: Accepted Name. Latest taxonomic scrutiny: 17-Oct-2001

Physical Description

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Family Laridae:

Medium to large birds, usually grey or white, often with black markings on the head or wings. They have stout, longish bills, and webbed feet.

Adult:

Body: Size: small Wings: Shape: fairly short Tail: gray Length: fairly short Shape: shallowly forked.

Adult Breeding Season:

Head: Cap: dusky Color: black Ear Coverts: dusky Bill: black Neck: black Body: Belly: black Breast: black Mantle: dull slate Rump: dull slate Size: small Underparts: white Legs: Leg Color: blackish-purple Wings: Shape: fairly short Linings: pale gray Tail: dull slate Crissum: white Length: fairly short Shape: shallowly forked.

Adult Summer:

Head: black Bill: black Neck: black Body: Underparts: black Wings: Shape: broad Tail: dark gray Length: short Shape: notched.

Adult Winter:

Head: Cap: dusky Color: white Ear Coverts: dusky Bill: black Body: Breast: gray smudge on sides Mantle: dull slate Rump: dull slate Size: small Underparts: white Legs: Leg Color: blackish-purple Wings: Shape: fairly short Linings: pale gray Tail: dull slate Length: fairly short Shape: shallowly forked.

Immature:

Head: Cap: dark dusky Color: white Ear Coverts: dusky Bill: black Body: Breast: gray smudge on sides Mantle: dull slate Rump: dull slate Size: small Underparts: white Legs: Leg Color: blackish-purple Wings: Shape: fairly short Linings: pale gray Tail: dull slate Length: fairly short Shape: shallowly forked.

Size/Age/Growth:

About 9 to 10 inches long, with a wingspan of 20 to 24 inches. Adults weigh about 2.3 ounces.

Images:

Distribution

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Range and Population

North America

Habitat

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Vegetation: freshwater marshes, saltwater and brackish marshes, freshwater lakes and ponds, freshwater marshes, coastal waters • Minimum Elevation: 0 meters • Maximum Elevation: 0 meters • Sensitivity to Disturbance: Medium.

Diet

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Primarily: Insects Lesser Quantities of: Aquatic Invertebrates Fish

Reproduction

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  • Breeding Habitat: Wetland-open water
  • Clutch Size: 3
  • Length of Incubation: 21-22 days
  • Days to Fledge: 21-28
  • Number of Broods: 1, occasionally 2 in South

Migration

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Migratory

Similar Species

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White-Winged Tern

Members of the genus Chlidonias:

There are approximately 30 species and subspecies in this genus: C. albostriatus (Black-Fronted Tern) · C. hibridus · C. hybrida (Whiskered Tern) · C. hybrida delalandii · C. hybrida hybrida · C. hybrida indica · C. hybrida javanica · C. hybrida leggei · C. hybrida sclateri · C. hybrida swinhoei · C. hybridus (Whiskered Tern) · C. hybridus fluviatilis · C. hybridus hybridus · C. hybridus indica · C. hybridus indicus · C. hybridus javanica · C. hybridus javanicus · C. hybridus swinhoei · C. leucoptera · C. leucopterus (White-Winged Tern) · C. niger (Black Tern) · C. niger niger (Black Tern) · C. niger nigra · C. niger ssp · C. niger surinamensis · C. nigra · C. nigra nigra · C. nigra surinamenses · C. nigra surinamensis · C. surinamensis

Bibliography

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  • Alsop, Fred J. III. Birds of North America - Eastern Region. First American Edition. Smithsonian Handbooks. DK Publishing, Inc. 2001.
  • Banks, R. C., R. W. McDiarmid, A. L. Gardner, and W. C. Starnes 2003. Checklist of Vertebrates of the United States, the U.S. Territories, and Canada.
  • BirdLife International. 2000. Threatened Birds of the World. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, U.K.
  • Ehrlich, P., Dobkin, D., and Wheye, D. (1988). The Birders Handbook: A Field Guide to the Natural History of North American Birds. New York: Simon and Schuster Inc. (info on clutch size, length of incubation, days to fledge and number of broods.)
  • Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc. (Length and wingspan info.)

More Info

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Notes

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Contributors:

Data Sources:

Accessed through GBIF Data Portal November 26, 2007:

Identifiers:

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Last Revised: May 17, 2008