Is the skull of the black-headed gull dimorphic? Analysis of shape variation
The black-headed gull (Chroicocephalus ridibundus) is a small bird belonging to the Laridae family. Their distribution and breeding broad area primarily cover the northern part of the Eurasian continent. Gulls are considered monomorphic birds, and distinguishing the sexes based on external morpholog...
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| Language: | English |
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Taylor & Francis Group
2025-12-01
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| Series: | The European Zoological Journal |
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| Online Access: | https://www.tandfonline.com/doi/10.1080/24750263.2025.2450460 |
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| author | P. Indykiewicz N. Manuta J. Bonecka O. Gündemir T. Szara |
| author_facet | P. Indykiewicz N. Manuta J. Bonecka O. Gündemir T. Szara |
| author_sort | P. Indykiewicz |
| collection | DOAJ |
| description | The black-headed gull (Chroicocephalus ridibundus) is a small bird belonging to the Laridae family. Their distribution and breeding broad area primarily cover the northern part of the Eurasian continent. Gulls are considered monomorphic birds, and distinguishing the sexes based on external morphological features is extremely difficult. In this study, a 3D shape analysis of the skull of black-headed gulls from central-northern Poland was performed to reveal the variation in shape between individuals and whether male skulls differ from females. For these purposes, 82 skulls were used (32 females and 50 males). 3D surface models of the skull were extracted using computed tomography. Twenty-one landmarks were designed on each skull. The principal components method was used to assess the variability of skull shapes. The first two principal components accounted for 48.28% of the cumulative shape variation. The most significant shape variation relative to PC1 was observed in the braincase. Positive PC2 values reflected the neurocranium expanding more rapidly dorso-ventrally with a wider orbit, and the nasofrontal hinge moved dorsally. According to the Procrustes ANOVA, the centroid size was statistically different between the sexes (p < 0.0001). Male skulls were longer than females. Neurocranium was wider in male gulls. The nasofrontal hinge was more caudal in females. The results of this study are consistent with the observations of other authors applying linear morphometry. |
| format | Article |
| id | doaj-art-3d7adf2eb72c4855a2ee6d1bbaf3a621 |
| institution | Kabale University |
| issn | 2475-0263 |
| language | English |
| publishDate | 2025-12-01 |
| publisher | Taylor & Francis Group |
| record_format | Article |
| series | The European Zoological Journal |
| spelling | doaj-art-3d7adf2eb72c4855a2ee6d1bbaf3a6212025-01-15T11:25:08ZengTaylor & Francis GroupThe European Zoological Journal2475-02632025-12-0192117418110.1080/24750263.2025.2450460Is the skull of the black-headed gull dimorphic? Analysis of shape variationP. Indykiewicz0N. Manuta1J. Bonecka2O. Gündemir3T. Szara4Department of Biology and Animal Environment, Bydgoszcz University of Science and Technology, Bydgoszcz, PolandInstitute of Graduate Studies, Istanbul University-Cerrahpasa, Istanbul, TurkeyDepartment of Small Animals Diseases and Clinic, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Warsaw, PolandDepartment of Anatomy, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, Istanbul, TurkeyDepartment of Morphological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Warsaw, PolandThe black-headed gull (Chroicocephalus ridibundus) is a small bird belonging to the Laridae family. Their distribution and breeding broad area primarily cover the northern part of the Eurasian continent. Gulls are considered monomorphic birds, and distinguishing the sexes based on external morphological features is extremely difficult. In this study, a 3D shape analysis of the skull of black-headed gulls from central-northern Poland was performed to reveal the variation in shape between individuals and whether male skulls differ from females. For these purposes, 82 skulls were used (32 females and 50 males). 3D surface models of the skull were extracted using computed tomography. Twenty-one landmarks were designed on each skull. The principal components method was used to assess the variability of skull shapes. The first two principal components accounted for 48.28% of the cumulative shape variation. The most significant shape variation relative to PC1 was observed in the braincase. Positive PC2 values reflected the neurocranium expanding more rapidly dorso-ventrally with a wider orbit, and the nasofrontal hinge moved dorsally. According to the Procrustes ANOVA, the centroid size was statistically different between the sexes (p < 0.0001). Male skulls were longer than females. Neurocranium was wider in male gulls. The nasofrontal hinge was more caudal in females. The results of this study are consistent with the observations of other authors applying linear morphometry.https://www.tandfonline.com/doi/10.1080/24750263.2025.2450460Avian anatomyshape analysissex determination |
| spellingShingle | P. Indykiewicz N. Manuta J. Bonecka O. Gündemir T. Szara Is the skull of the black-headed gull dimorphic? Analysis of shape variation The European Zoological Journal Avian anatomy shape analysis sex determination |
| title | Is the skull of the black-headed gull dimorphic? Analysis of shape variation |
| title_full | Is the skull of the black-headed gull dimorphic? Analysis of shape variation |
| title_fullStr | Is the skull of the black-headed gull dimorphic? Analysis of shape variation |
| title_full_unstemmed | Is the skull of the black-headed gull dimorphic? Analysis of shape variation |
| title_short | Is the skull of the black-headed gull dimorphic? Analysis of shape variation |
| title_sort | is the skull of the black headed gull dimorphic analysis of shape variation |
| topic | Avian anatomy shape analysis sex determination |
| url | https://www.tandfonline.com/doi/10.1080/24750263.2025.2450460 |
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