Complex sentence: Several other birds, which are sometimes called turkeys, are not particularly closely related: the Australian Brushturkey is a megapode, and the bird sometimes known as the "Australian Turkey" is the Australian Bustard, a gruiform.
Split into simpler sentences: Several other birds, which are sometimes called turkeys, are not particularly closely related. The Australian Brushturkey is a megapode, and the bird sometimes known as the "Australian Turkey" is the Australian Bustard, a gruiform.