But what is it?
The names of bird species can be misleading. For example, several North American species called sparrows, such as White-crowned Sparrow (Zonotrichia leucophrys) or Fox Sparrow (Passerella iliaca), are actually buntings. These “American Sparrows” are more closely related to Old World buntings (family Emberizidae) than they are to the Old World sparrows (family Passeridae). A similar case concerns the Egyptian Goose (Alopochen aegyptiaca). Despite its name, it is not a goose. But then, what is it?
The True Geese
First of all, what are “true geese”? This group of waterbirds comprises two genera – Anser and Branta – in the subfamily Anserinae. The genus Anser contains the grey geese and the white geese (sometimes placed in a separate genus, Chen), while the genus Branta houses the black geese. Below you can see all the species in this subfamily. The tree in the middle depicts the evolutionary relationships between the species, based on my own work (you can find the original paper here or read the summary here).
Where does the Egyptian Goose fit in?
The Egyptian Goose does not occur in the circle above. When you reconstruct the evolutionary history of the family Anatidae (ducks, geese and swans), The Egyptian Goose ends up in a group with several shelducks, such as Common Shelduck (Tadorna tadorna) and Australian Shelduck (Tadorna tadornoides). This nicely illustrates that the Egyptian Goose is not a goose, but a duck!
So, there you have it: the Egyptian Goose is actually a duck (and probably a shelduck). But I can understand the confusion. With its long neck it does resemble a true goose. Moreover, Egyptian Goose has hybridized with several goose species, such as Greylag Goose (Anser anser) and Canada Goose (Branta canadensis). However, hybridization is very common among waterfowl and Egyptian Goose has interbred with numerous other – not so closely related – species, including Muscovy Duck (Cairina moschata) and Mallard (Anas platyrhynchos). You can find an overview of all known Egyptian Goose hybrids here.
To conclude, you can keep using the name Egyptian Goose but just keep in mind that it is actually a duck…
Donne-Goussé, C., Laudet, V., & Hänni, C. (2002). A molecular phylogeny of anseriformes based on mitochondrial DNA analysis. Molecular Phylogenetics and Evolution, 23:339-356.
Ottenburghs, J., Megens, H.-J., Kraus, R.H.S., Madsen, O., van Hooft, P., van Wieren, S.E., Crooijmans, R.P.M.A., Ydenberg, R.C., Groenen, M.A.M. & Prins, H.H.T. (2016). A Tree of Geese: A Phylogenomic Perspective on the Evolutionary History of True Geese. Molecular Phylogenetics and Evolution. 101:303-313.