Some Remarks on Bird's Brain and Behavior under the Constraints of Domestication

Figure 6

Different breeds of ducks. (a) Crested Duck with a typical feather crest. (b) Indian Runner Duck with characteristic upright body posture. (c) Black East Indian Duck with the typical green shining feathering. (d) Hookbill Duck: the bill will become more and more hooked over the years. (e) Call Duck, the smallest (and loudest) of the duck breeds.