It depends on the species.
Usually and universally it is called a flock of birds.
A group of Cormorants can be referred to as a flight of birds. Whereas a group of Jays can be referred to as a band of birds.
Please see the related link, it gives a list of the names of bird groups or gatherings by species.
what is the significant of birds first flight
The Birds - band - was created in 1964.
The Birds - band - ended in 1967.
Birds are groups of animals equipped for flight.
A flight pattern is the direction of which or how a flock of birds fly.
The birds quickly took flight.
They mimicked the flight of birds.
The study of birds in flight helped many engineers to make wing designs of an aircraft. The aerodynamics involved in the flight of the bird impressed the engineers. Studying birds in flight hepled aircraft designers to get the Airbus A-380 airborne.
Wings and feathers
Mostly for flight.
A flock
The Yard Birds