why is an American bird called a Turkey?

Centuries ago, Constantinople was an important hub of international trade, where merchants sold goods from Africa and the Far East to distributors in Europe. These products, instead of retaining a sense of their origin, often became known by the nationality of the exporters. For example, Persian rugs sold wholesale by Turkish vendors were called "Turkish rugs." In turn, one popular type of bird shipped from Africa, called a Guinea fowl, became known as "Turkey cock" throughout England.

And, when British settlers arrived in the New World and encountered a large woodland bird that looked a bit like the Guinea fowl fowl they'd grown fond of eating back in England -- perhaps out of confusion that the two were the same species, or maybe in longing for something familiar so far from home -- they ended up referring to this bird as a "Turkey cock" too. Later, it was shortened to simply 'turkey'.

Another factor that helped perpetuate this unusual choice of names occurred when these new North American birds became a popular commodity throughout the world -- sure enough, mostly by way of Turkish merchants.

Ironically, the name of turkeys in the Turkish language is even more geographically off base; their called Hindi, short for "bird from India." The Turks, better than anyone, knew the birds weren't from their homeland, but may have originally thought they came from India -- thanks to a little miscalculation by Columbus.

so, enjoy your turkey cock, folks! source.