If your bird escapes outside, DO NOT GIVE UP. You CAN get your bird back. Below is a link to Barbara Heidenreich's website with several great tips on how to recover your parrot. Tip number one is: DO NOT LOSE SIGHT OF YOUR BIRD. Even if you do lose sight, you can still recover your parrot. Barb's website even includes flyers with pictures of common species so that you can quickly print them and start circulating them in your neighborhood. Please click on the link below for some important tips and very helpful ideas.
http://goodbirdinc.com/help-escape.html
Barb also has a brand new DVD out on what to do if your parrot escapes. I have not had a chance to see it yet, but I do have it on order.