I have one of those ceramic pie birds that vent steam from a pie while it bakes. What benefit does using this provide to the end result? Also, in what types of pies should it be used?
From this site I found that there are two major benefits to using a pie bird
Prevent the pie from boiling over in the oven by allowing the steam created when the fruit filling or other contents are cooking to escape from inside the pie
Support the pastry crust in the center of the pie, so that it did not sag in the middle
Based on the site it seems that they can be put in any type of pie.