Merlin

Black Tern Identification

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The Four Keys to ID

  • Size & Shape

    A small and delicately built seabird with a thin, pointed bill; long, pointed wings; a shallowly forked tail; and short legs.

    Relative Size

    Larger than a Least Tern, smaller than a Common Tern.

    Relative Sizebetween robin and crowbetween robin and crow
    Measurements
    • Both Sexes
      • Length: 9.1-10.2 in (23-26 cm)
      • Weight: 1.8-2.1 oz (50-60 g)
      • Wingspan: 22.4-23.6 in (57-60 cm)

Regional Differences

American Black Terns belong to the subspecies surinamensis, and Old World Black Terns belong to the slightly larger subspecies niger. Compared to surinamensis, Old World niger is paler below in breeding plumage, and in other plumages has a much smaller mark at the side of the breast. American Black Terns have been documented in Europe and the British Isles, but there are no records of Old World Black Terns in North America as of 2019.