It depends if their are a lot of cats in your neighbourhood, if their isnt it may live a couple of hours before it does of cold. Unless its quite old then it may last until it gets run over in 2 days time maximum they last is 3 days.
I can give you advice if you actually saw one
If a baby bird is out of it's nest and its on the ground; It's windy too, how long will it live before its demise.
