Is aves a proper noun

Answer 1

Although scientific literature often capitalizes the word Aves (plural, a class of birds), there is no reason to consider the word a proper noun. When used as the plural form of the greeting or farewell (ave), it is a common noun.

Answer 2

The noun 'ave' (lower case a) is a common nounas an obsolete word of greeting.

The noun 'Ave' (uppercase A) is a proper noun as the shortened form for the Roman Catholic prayer, the Ave Maria.