I talk a lot about avian digestive systems and respiratory systems but it’s been a while since we talked about feathers. Generally, the birds that we keep as pets have anywhere from 5000 to 7000 feathers. Waterfowl like certain species of ducks can have more than 11,000. Yes, scientists have actually counted them.

From Wikipedia we learn:

Feathers are among the most complex integumentary system appendages found in vertebrates and are formed in tiny follicles in the epidermis, or outer skin layer, that produces keratin proteins.

The β-keratins in feathers, beaks, and the claws, scales, and shells of reptiles — are composed of protein strands hydrogen-bonded into β-pleated sheets, which are then further twisted and crosslinked by disulfide bridges into structures even tougher than the α-keratins of mammalian hair, horns, and hoof.

β-keratin or beta-keratin is a protein in the keratin family. β-keratin is rich in stacked β pleated sheets. Keratin is one of a family of fibrous structural proteins. Keratin is the protein that protects epithelial cells from damage or stress.

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