However, depending on what you're trying to convey, here are some options:
* Avianity: This is a less common word, but it specifically refers to the state of being a bird.
* Flight: This refers to the act of flying, a characteristic of many birds.
* Song: This represents the sound of birds singing, a common attribute.
* Beauty: This could be used if you're emphasizing the aesthetic quality of birds.
* Freedom: This can symbolize the sense of liberation birds often represent.
Ultimately, the best abstract noun to use depends on the specific context and what you want to express about birds.