Here are a few options depending on your interpretation:
1. General Bird Categories:
* Bird: This is the most general noun for any bird.
* Feathered friend: This is a more informal and affectionate term.
* Avian: This is a more scientific term.
2. Specific Bird Types:
* Species: If you are talking about a particular type of bird, the species name is the most specific noun, like "robin," "eagle," or "hummingbird."
* Genus: This is a broader category than species, grouping birds with similar characteristics. For example, the genus *Falco* includes various falcons.
* Family: This is an even broader category, grouping birds with shared evolutionary history. For example, the family *Falconidae* includes falcons, caracaras, and kestrels.
3. Physical Parts of a Bird:
* Wing: This refers to the bird's wings.
* Feather: This refers to the bird's feathers.
* Beak: This refers to the bird's beak.
Ultimately, the "three common nouns" depend on the context and what you're trying to express.