Development of sexual dimorphism and sexing of Baltic Herring Gull (Larus argentatus argentatus) in successive age classes

Włodzimierz Meissner , Andrzej Kośmicki , Artur Niemczyk , Izabela Fischer

Abstract

Discriminant functions based on external body size measurements are widely used to sex different gull species with great accuracy. However, all of them have been derived for adult birds, which puts into question their usefulness for sexing immatures due to possible changes in size as birds mature. To address this issue, discriminant functions that allow sexing of Herring Gulls in immature age classes with an accuracy of 88–100% were developed. In total, 247 males and 111 females of wintering Herring Gulls, including birds in the first, second and third winter plumages and individuals in adult plumage, were measured and sexed in the region of the Gulf of Gdańsk (southeastern Baltic coast). In all age classes, total head length and bill depth were the best traits for sexing Herring Gulls. However, bill depth, but not total head length, increased with age. Hence, in the first and second winter plumages, total head length made a much higher contribution to the discriminant function than bill depth. In the third winter plumage, bill depth became more important. For individuals in adult plumage, however, the contribution of total head length and bill depth were nearly the same. Hence, using discriminant equations derived for adults resulted in erroneous sexing of 4.5–8.9% of immature males, which were identified as females, and illustrates the importance of deriving age-specific discriminant functions.
Author Włodzimierz Meissner KEiZK
Włodzimierz Meissner,,
- Department of Vertebrate Ecology and Zoology
, Andrzej Kośmicki
Andrzej Kośmicki,,
-
, Artur Niemczyk
Artur Niemczyk,,
-
, Izabela Fischer KEiZK
Izabela Fischer ,,
- Department of Vertebrate Ecology and Zoology
Other language title versions
Journal seriesWaterbirds, ISSN 1524-4695
Issue year2017
Vol40
No1
Pages24-32
Publication size in sheets0.5
Keywords in EnglishBaltic Sea, discriminant analysis, herring gull, Larus argentatus, sexing, sexual dimorphism
DOIDOI:10.1675/063.040.0104
URL http://dx.doi.org/10.1675/063.040.0104
Languageen angielski
Score (nominal)25
ScoreMinisterial score = 25.0, 20-12-2017, ArticleFromJournal
Ministerial score (2013-2016) = 25.0, 20-12-2017, ArticleFromJournal
Publication indicators WoS Impact Factor: 2016 = 0.678 (2) - 2016=0.898 (5)
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