United Flight 766, a Boeing 757, was headed to San Francisco when a crack appeared in a cockpit window.
The flight was diverted to Indianapolis, where it landed safely Saturday night.
United says the 138 passengers aboard were put on another plane.
Maintenance crews are examining the aircraft.
A passenger on board the plane posted a picture of the windshield on Twitter, and tweeted: "United Flight 766 New York to San Francisco bird hit window. Kudos to pilots for getting us down safe."