A while ago, ferrebeekeeper added the new category “fowl”. So far, entries in this category include a write-up of predatory ducks, geese the size of dinosaurs, and terrifying people in duck costumes (not to mention the yet-to-be incorporated category of turkeys)—a pretty auspicious start for the topic! But what exactly does “fowl” mean? Although in English, “fowl” can be used as a general term for all birds, the word has a more specific scientific meaning: fowl denotes a combined group of two extremely important biological orders of birds, the Galliformes (game fowl) and the Anseriformes (waterfowl). Cladists, taxonomists who classify biological organisms according to shared ancestors, have discovered that birds from these two orders share numerous physiological features and descend jointly from a common ancestor (which most likely lived in the Cretaceous or earlier).
The vast majority of economically/agriculturally important domesticated birds are either galliformes or waterfowl (I am omitting pet birds like canaries, parrots, emus, pigeons, and, um, gyrefalcons, and concentrating on farm birds). Galliformes include pheasants, quail, grouse, turkeys, junglefowl, partridges, and guineafowl (among other taxa, living and extinct). Waterfowl include geese, ducks, swans, and screamers. Cladists (with typical lack of euphony) call the combined group the “Galloanserae”.
Although golden pheasants, black swans, and green peacocks seem extremely different (except in terms of extravagant beauty), the birds of Galloanserae share surprising similarities. They produce prolific clutches of eggs–which is especially unusual for large birds–and the resultant chicks are unusually precocious. Baby ducks or turkeys can soon run after their mother and baby megapodes emerge from the incubation mound ready to fly (compare that with the passerines or raptors whose young are helpless and immobile for weeks or longer).
Additionally fowl are polygynous or polygamous. Many other birds form close monogamous relationships (some of which last for life) but fowl tend to be rather, er, promiscuous. Domestic chickens are notable for their harem-style sexual relations and dabbling ducks are infamous for the violent amoral chaos of their courtship. Likewise, fowl can hybridize easily and in strange ways. Birds which live in different genera can have courtships, produce eggs, and even conceive offspring. In fact common mallard ducks (Anas platyrhynchos) originated in Siberia but have interbred so frequently with American black duck (Anas rubripes), and with Northern Pintail (Anas acuta) that the species distinctions are breaking down. Stranger and more unlikely fowl pairings are not unknown (and the resultant offspring are sometimes not infertile) but I will leave those soap opera stories for another day….