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Skua
species of Stercorariidae


© Thomas Hochebner
juv.
number longest
primary 10 per wing approx. 287.5mm n=1
P9 (100%)
secondary 20-21 per wing approx. 173.0mm n=1
S16 (100%)
retrix 12
approx. 161.0mm n=1
R5 (100%)
wing length1 hand-wing-index1,2 (HWI) primaries-index wing length/longest primary ratio hand-wing-index/primaries-index ratio
377 - 410mm n=5 53 - 53% n=4 41 - 41% n=1 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: 377 - 410mm n=5

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: 53 - 53% n=4,
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

Algeria · Anguilla (origin uncertain) · Antigua and Barbuda · Austria · Barbados · Belgium · Belize · Bermuda (vagrant) · Brazil · Bulgaria · Cabo Verde · Canada · Colombia · Côte d'Ivoire (vagrant) · Croatia (vagrant) · Cuba (vagrant) · Cyprus (origin uncertain) · Czechia (vagrant) · Denmark · Dominica · Egypt · Faroe Islands · Finland (vagrant) · France · French Guiana · Gambia (origin uncertain) · Germany · Ghana (vagrant) · Gibraltar · Greece (vagrant) · Greenland · Guadeloupe (vagrant) · Guinea (origin uncertain) · Guinea-Bissau (origin uncertain) · Guyana · Hungary (vagrant) · Iceland · Ireland · Israel (vagrant) · Italy · Latvia (vagrant) · Lebanon (origin uncertain) · Liberia (vagrant) · Libya · Lithuania (vagrant) · Luxembourg (vagrant) · Malta (vagrant) · Martinique · Mauritania · Montenegro (vagrant) · Montserrat · Morocco · Netherlands · Nigeria (vagrant) · Norway · Panama · Poland (vagrant) · Portugal · Puerto Rico · Romania (vagrant) · Russian Federation · Saint Kitts and Nevis · Saint Lucia · Saint Pierre and Miquelon · Saint Vincent and the Grenadines · Senegal (vagrant) · Serbia (vagrant) · Sierra Leone (origin uncertain) · Slovakia · Slovenia (vagrant) · Spain · Suriname · Svalbard and Jan Mayen · Sweden · Switzerland (vagrant) · Syrian Arab Republic (origin uncertain) · Trinidad and Tobago (origin uncertain) · Tunisia · Türkiye (vagrant) · United Kingdom of Great Britain and Northern Ireland · United States of America · Venezuela, Bolivarian Republic of (origin uncertain) · Virgin Islands, British (origin uncertain) · Virgin Islands, U.S. (origin uncertain) · Western Sahara (origin uncertain) ·
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
    protected