Birds are very clean animals, despite what people may complain over regarding pigeons and parked cars. Even the lowly chicken, if given the option, would prefer not to live in cramped quarters and walk in its own excrement. Birds spend the vast majority of their resting moments cleaning themselves or each other, a process known as allopreening. To a bird, cleanliness and hygeine are of utmost importance, a matter of life and death. A skin ailment, dirty feet, an infection in the feather shaft, all can result in the failure of flight function, lameness and, ultimately, death.
Cleanliness and purity are defining features of a bird as much as eggs and feathers are. It probably comes to no surprise that birds have such a strong function in the healing and cleansing rituals and ceremonies within a wide variety of traditions throughout the world, but particularly within the ATR/DTR traditions and systems, such as hoodoo. Eggs cleanse and absorb negative energy by being rolled over various parts of the body, or on a specific afflicted area. They are then discarded by a variety of means which include hurling them at a crossroads or at a tree. They are sometimes cracked into a bowl and the contents interpreted for divinatory purposes. Wings and feathers also dust off debris and negativity. Whole birds are also used in the same manner as the egg, and are then humanely offered up in sacrifice and discarded, as their meat has become unfit to eat from absorbing the bad luck and negativity of the people.
Note that the above isn’t limited to chickens, but they are the most easily accessible of birds and have a long history of domestication. Other birds are also used and have a long pedigree of traditions and symbolisms associated with cleansing and purity, for example the dove or white pigeon, but it would be exhaustive to try to cover them all at this time. As an augur I’ll attest that birds make very strong and deeply meaningful spiritual allies and tools. This may also explain (aside from my own germophobia) why I am very aware of the cleanliness of my own body and surroundings, despite being elbows deep in such a visceral and sometimes very dirty spiritual tradition. The hawk never at all hesitates getting himself dirty in the heat of the hunt, but you must excuse and have patience with him when he takes his time to ensure that the blood is scraped from his beak and talons, and every feather cleaned and put back into place for the next hunt.