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Gull-billed Tern
species of Sternidae

wing length1 hand-wing-index1,2 (HWI) primaries-index wing length/longest primary ratio hand-wing-index/primaries-index ratio
271 - 326mm n=14 65 - 68% n=8 no data available no data available no data available
detailed information

The wing length is measured on the flattened and straightened wing ("maximum chord") from the carpal joint to the tip of the longest primary feather, the so-called "Kleinschmidt-method".

combined data from:
Avonet1: 271 - 326mm n=14

The hand-wing-index, introduced by Kipp 1959, is calculated as the ratio of the hand length (difference between the length of the longest primary and the first secondary) to the wing length.

combined data from:
Avonet1: 65 - 68% n=8,
The primaries-index is calculated as the ratio of the longest primary feather length to the first (outermost) secondary. It is the equivalent of the hand-wing index for feather measurements. The wing length/longest primary ratio is calculated as the ratio of the wing length to the length of the longest primary feather. The hand-wing-index/primaries-index ratio is calculated as the ratio of the hand-wing index to the primaries-index.
1 Tobias, J. A., et al. (2022). AVONET: morphological, ecological and geographical data for all birds.
2 Kipp, Friedrich A.: "Der Handflügel-Index als flugbiologisches Maß", erschienen in "Vogelwarte - Zeitschrift für Vogelkunde", 1959, Band 20, Heft 1


country allocations

extant

Afghanistan · Algeria · Angola (vagrant) · Anguilla · Antigua and Barbuda · Argentina · Armenia · Australia · Azerbaijan · Bahamas · Bahrain · Bangladesh · Barbados · Belgium (vagrant) · Belize · Benin · Bermuda (vagrant) · Bonaire, Sint Eustatius and Saba (vagrant) · Bosnia and Herzegovina (vagrant) · Botswana (vagrant) · Brazil · Brunei Darussalam · Bulgaria · Burkina Faso · Burundi · Cambodia · Cameroon · Canada (vagrant) · Cayman Islands · Chad · China · Colombia · Comoros (vagrant) · Congo, The Democratic Republic of the · Costa Rica · Côte d'Ivoire · Croatia (vagrant) · Cuba · Curaçao · Denmark · Djibouti · Dominica · Dominican Republic · Ecuador · Egypt · El Salvador · Eritrea · Ethiopia · Finland (vagrant) · France · French Guiana · Gabon (vagrant) · Gambia · Germany · Ghana · Greece · Guadeloupe · Guam (vagrant) · Guatemala · Guinea · Guinea-Bissau · Guyana · Haiti · Honduras · Hungary (vagrant) · India · Indonesia · Iran, Islamic Republic of · Iraq · Ireland (vagrant) · Italy · Jamaica · Japan · Jordan · Kazakhstan · Kenya · Korea, Republic of (vagrant) · Kuwait · Kyrgyzstan · Lebanon (vagrant) · Liberia · Luxembourg (vagrant) · Malawi · Malaysia · Mali · Martinique · Mauritania · Mexico · Mongolia · Montenegro (vagrant) · Morocco · Myanmar · Nicaragua · Niger · Nigeria · Norway (vagrant) · Oman · Pakistan · Panama · Papua New Guinea · Peru · Philippines · Poland (vagrant) · Portugal · Puerto Rico · Qatar · Romania · Russian Federation · Rwanda · Saint Barthélemy · Saint Lucia (vagrant) · Saint Martin (French part) (vagrant) · Saint Vincent and the Grenadines (vagrant) · Saudi Arabia · Senegal · Serbia (vagrant) · Seychelles (vagrant) · Sierra Leone · Sint Maarten (Dutch part) (vagrant) · Slovakia (vagrant) · Slovenia (vagrant) · Somalia · South Africa (vagrant) · South Sudan · Spain · Sri Lanka · Sudan · Suriname · Sweden (vagrant) · Taiwan, Province of China · Tajikistan · Tanzania, United Republic of · Thailand · Timor-Leste · Togo · Trinidad and Tobago · Tunisia · Türkiye · Turkmenistan · Turks and Caicos Islands · Uganda · Ukraine · United Arab Emirates · United Kingdom of Great Britain and Northern Ireland (vagrant) · United States of America · Uruguay · Uzbekistan · Venezuela, Bolivarian Republic of · Viet Nam · Virgin Islands, British · Virgin Islands, U.S. · Western Sahara · Yemen · Zambia · Zimbabwe (vagrant) ·
source: IUCN 2025. IUCN Red List of Threatened Species. Version 2025-1 <www.iucnredlist.org>
assessment data: |

Waders, gulls and auks

conservation status

  • CITES
    not listed
  • Regulation (EG) Nr. 865/2006
    not listed
  • German Federal Nature Conservation Act §44
    strictly protected