Is there such thing as a fleet of birds?

The general collective noun for birds is a flock of birds.

Many individual species of birds also have their own collective nouns, for example:

• a charm of goldfinches
• a convocation of eagles
• a drift of swans
• a host of sparrows
• a parliament of owls
• a stand of flamingos
• a watch of nightingales
• a wedge of geese

The noun fleet is a standard collective noun for a fleet of ships, a fleet of planes, or a fleet of vehicles of any kind.