Behavior is called mobbing

Its not worth it for the predator animal to go after a bunch of smaller birds that are harassing it so they tend to leave. Its also done to steal the predators meal when they leave or to distract it while another bird steals its food. Also draws attention to them to prevent them going stealth, which can affect bjrds like owls, who tend to be victim to this type of attack from prey birds. This makes them leave because their main weapon is stealth and when their cover is blown, they will have a harder tome catching prey (including the mobbing birds’ babies)