Plumage changes in an intersex Mallard Anas platyrhynchos over a six-year period

Authors

DOI:

https://doi.org/10.34080/os.v31.22427

Keywords:

Anatidae, duck, field studies, gradual masculinization, longitudinal observations, phenotype, photographic documentation

Abstract

Intersex individuals with a mixture of female and male plumage traits are reported regularly, but at low frequency. Here we describe the changes in plumage in a Mallard Anas platyrhynchos intersex individual over six years (2015–2020), from a mixed female–male phenotype to a predominantly male phenotype. Already at the first observation, typical male characteristics were present, such as greyish-white tail with two central curved black rectrices and a greenish tinge to parts of the head. The bird attained a more male-like plumage with the next moult and maintained that plumage for the rest of the study period. However, presence of female-patterned body feathers continued until 2019, but in reduced frequency, except for the cheeks and ear-coverts, which displayed a variation in colour. The bill remained female-patterned throughout and the bird did not enter eclipse plumage.

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References

Andersson S, Bengtsson D, Hellström M & Waldenström J. 2016. Age and sex determination of Mallards Anas platyrhynchos in autumn. Ornis Svecica 26: 61–81. https://doi.org/10.34080/os.v26.22530

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Wirdheim A (red). 2020. Sveriges fåglar 2020. BirdLife Sverige, Stockholm & Svensk Fågeltaxering, Lunds universitet, Lund. 28 sidor. Tillgänglig från https://www.fageltaxering.lu.se/sites/default/files/files/Rapporter/sveriges_faglar_2020.pdf.

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Published

2021-06-04

How to Cite

Sjögren, A.-K., & Waldenström, J. (2021). Plumage changes in an intersex Mallard Anas platyrhynchos over a six-year period. Ornis Svecica, 31, 68–74. https://doi.org/10.34080/os.v31.22427

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Short Communications

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