The Penguin has the brilliant Harold create a technology that can control birds.
Penguin picked up a hunchback mute ( Harold) who turned out to be a mechanical genius. He built devices that would allow Penguin to control birds. Thinking of the profit margin, Penguin soon had the birds wreaking havoc all over Gotham City. He also had them kidnap an actress that he had an obsession with.
[continued in Detective Comics #615 - The Penguin Affair part 2 : Bird of Ill Omen!]