Exploring Sexual Dimorphism in Kadaknath Chickens Through Head Shape Analysis Using Geometric Morphometrics
39
Abstract
Sexual dimorphism plays a crucial role in the biology and management of poultry species, influencing breeding, behavior, and productivity. This study aims to investigate sexual dimorphism in Kadaknath chickens using geometric morphometric analysis of head shape variation A total of 16 adult Kadaknath chickens (8 males and 8 females) were analyzed using landmark-based geometric morphometric analysis on lateral head images. Principal Component Analysis (PCA), Canonical Variate Analysis (CVA), and Partial Least Squares (PLS) analysis were performed to assess shape variation and sexual dimorphism. PCA revealed clear shape differences between sexes, with males displaying more pronounced features in the beak, eye, and comb regions. Males also exhibited less within-group shape variation, suggesting greater shape conservation. Females showed narrower ear lobes, shorter combs, and higher shape variation along PC1. CVA confirmed sex-specific differences, particularly in the comb and eye regions. No significant difference in centroid size was observed between sexes, indicating the absence of sexual size dimorphism. PLS analysis demonstrated that between-group variation was greater than within-group variation. The study confirms pronounced sexual dimorphism in Kadaknath chickens, primarily attributed to shape differences independent of overall size. These findings contribute to breed characterization, aid in sex identification, and support conservation strategies. The small sample size may limit the reliability of the CVA results. Future research incorporating 3D morphometrics and larger populations is recommended.
Downloads
References
Almeida E C de J, Carneiro P L S, Nunes L A, Malhado C H M, Campos B M, Figueiredo N E M et al. 2023. Breed characterization of native chickens based on their head shape and size. DELOS: Desarrollo Local Sostenible 16 (45): 1876–90. https://doi.org/10.55905/rdelosv16.n45-026
Au -Nuzzolese E, Randolph-Quinney P, Randolph-Quinney J A and Vella G D. 2019. Geometric morphometric analysis of sexual dimorphism in the mandible from panoramic x-ray images. Journal of Forensic Odonto Stomatology 37 (2): 35–44. http://www.scopus.com/inward/record.url?scp=85072964901&partnerID=8YFLogxK
Badyaev A V and Hill G E. 2003. Avian sexual dichromatism in relation to phylogeny and ecology. Annual Review of Ecology, Evolution and Systematics 34 (1): 27–49. https://doi.org/10.1146/annurev.ecolsys.34.011802.132441
Begna D, Bacha T, Boki S and Bekana K. 2025. Characterization of indigenous chicken phenotypes in Liban Jawi District, Ethiopia: A qualitative and quantitative analysis. PLoS One 20 (1): e0307793. https://doi.org/10.1371/journal.pone.0307793
Bell A M, Hankison S J and Laskowski K. 2009. The repeatability of behaviour: a meta-analysis. Animal Behaviour 77 (4): 771–83.
Caron F S and Pie M R. 2024. The macroevolution of sexual size dimorphism in birds. Biological Journal of the Linnean Society. https://doi.org/10.1093/biolinnean/blad168
Caspar K R, Müller J and Begall S. 2021. Effects of sex and breeding status on skull morphology in cooperatively breeding Ansell’s mole-rats and an appraisal of sexual dimorphism in the Bathyergidae. Frontiers in Ecology and Evolution 9: 638754.
Curevo J J and Møller A P. 1999. Phenotypic variation and fluctuating asymmetry in sexually dimorphic feather ornaments in relation to sex and mating system. Biological Journal of the Linnean Society 68 (4): 505–29.
Dalton H A, Wood B J, Widowski T M, Guerin M T and Torrey S. 2017. An analysis of beak shape variation in two ages of domestic turkeys (Meleagris gallopavo) using landmark-based geometric morphometrics. PLoS One 12 (9): e0185159. https://doi.org/10.1371/journal.pone.0185159
Desta T T. 2019. Phenotypic characteristic of junglefowl and chicken. World’s Poultry Science Journal 75 (1): 69–82.
Dubiec A and Zagalska-Neubauer M. 2006. Molecular techniques for sex identification in birds. Biological Letters 43: 3–12.
Eberhard W. 1996. Female Control: Sexual Selection by Cryptic Female Choice. Princeton University Press, Princeton.
Fairbairn D J. 2007. Introduction: The enigma of sexual size dimorphism. In: Fairbairn D J, Blanckenhorn W U and Székely T (Eds), Sex, Size and Gender Roles: Evolutionary Studies of Sexual Size Dimorphism. Oxford University Press, Oxford.
Haunshi S, Devatkal S, Prince L L L, Ullengala R and Ramasamy K et al. 2022. Carcass characteristics, meat quality and nutritional composition of Kadaknath, a native chicken breed of India. Foods 11 (22): 3603. https://doi.org/10.3390/foods11223603
Johanna J C, Dana G, Michael V and Paul M. 2014. A pilot study of sexual dimorphism in the head morphology of domestic dogs. Journal of Veterinary Behavior 9 (1): 43–46.
Joseph N S, Robinson F E, Renema R A and Thorsteinson K A. 2003. Comb growth during sexual maturation in female broiler breeders. Journal of Applied Poultry Research 12 (1): 7–13.
Kimbell R, Marry C M S and Braun E L. 2011. A macroevolutionary perspective on multiple sexual traits in the Phasianidae (Galliformes). International Journal of Evolutionary Biology 2011: 423938. https://doi.org/10.4061/2011/423938
Klingenberg C P. 2013. Cranial integration and modularity: insights into evolution and development from morphometric data. Hystrix, Italian Journal of Mammalogy 24 (1): 43–58.
Li X and Kokko H. 2021. Sexual dimorphism driven by intersexual resource competition: Why is it rare, and where to look for it? Journal of Animal Ecology 90 (8): 1831–43.
Møller A P. 1994. Repeatability of female choice in a monogamous swallow. Animal Behaviour 47 (3): 643–48.
Mukhtar N and Khan S H. 2012. Comb: An important reliable visual ornamental trait for selection in chickens. World’s Poultry Science Journal 68 (3): 425–34.
Navarro J, Kaliontzopoulou A and González-Solís J. 2009. Sexual dimorphism in bill morphology and feeding ecology in Cory’s shearwater (Calonectris diomedea). Zoology 112 (2): 128–38.
Ó Marcaigh F, Kelly D J, Analuddin K, Karya A and Lawless N et al. 2020. Cryptic sexual dimorphism reveals differing selection pressures on continental islands. Biotropica 00: 1–9. https://doi.org/10.1111/btp.12852
Rohlf F J. 2015. The TPS series of software. Hystrix, The Italian Journal of Mammalogy 26 (1): 9–12.
Sansalone G, Paolo C, Riccardo C, Stephen W, Castiglione S and Pasquale R. 2022. Trapped in the morphospace: The relationship between morphological integration and functional performance. Evolution 76 (9): 2020–31. https://doi.org/10.1111/evo.14575
Seddon N, Botero C A, Tobias J A, Dunn P O and Macgregor H E et al. 2013. Sexual selection accelerates signal evolution during speciation in birds. Proceedings of the Royal Society B: Biological Sciences 280 (1766): 20131065. https://doi.org/10.1098/rspb.2013.1065
Sharma R, Sehrawat R, Ahlawat S, Sharma V, Parmer A et al. 2022. An attempt to valorize the only black meat chicken breed of India by delineating superior functional attributes of its meat. Scientific Reports 12: 3555. https://doi.org/10.1038/s41598-022-07575-9
Silva S T D D, Pagthinathan M, Bandara S and Pathirana I N. 2023. Sex identification methods of birds: A review. Asian Journal of Medical and Biological Research 9 (4): 134–44. https://doi.org/10.3329/ajmbr.v9i4.69414
Toalombo Vargas P A, Navas González F J, Landi V, León Jurado J M and Delgado Bermejo J V. 2019. Sexual dimorphism and breed characterization of Creole hens through biometric canonical discriminant analysis across Ecuadorian agroecological areas. Animals 10 (1): 32. https://doi.org/10.3390/ani10010032
Vignon M and Sasal P. 2010. The use of geometric morphometrics in understanding shape variability of sclerotized haptoral structures of monogeneans (Platyhelminthes) with insights into biogeographic variability. Parasitology International 59 (2): 183–91.
Wright D, Boije H, Meadows J R S, Bed’hom B and Gourichon D et al. 2009. Copy number variation in intron 1 of SOX5 causes the pea-comb phenotype in chickens. PLoS Genetics 5 (6): e1000512. https://doi.org/10.1371/journal.pgen.1000512
Published
Issue
Section
License
Copyright (c) 2026 The Indian Journal of Animal Sciences

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
The copyright of the articles published in The Indian Journal of Animal Sciences is vested with the Indian Council of Agricultural Research, which reserves the right to enter into any agreement with any organization in India or abroad, for reprography, photocopying, storage and dissemination of information. The Council has no objection to using the material, provided the information is not being utilized for commercial purposes and wherever the information is being used, proper credit is given to ICAR.