Well, here is something you may never heard of. End Survival is the one of the few maps that makes sure you are in the end or the nether. If you are not in the end, or the nether, but in the overworld, you will be sent to the end in a matter of seconds, using command blocks. You have almost no time to grab dirt in the overworld, as there is a comparator clock that just sends every entity in the end. Also, every entity may follow you to the end. So, that means, if chickens spawn in the overworld, guess what? You got some chickens!
This file is in WinRAR format, so if you want to download this save, you need to download Winrar at http://www.rarlab.com/ (Don't worry, its free!)
If I do MCEdit Edition, you may need MCEdit, and you can get it at http://www.mcedit.net/ (Don't worry, its free!)

PM me if links are broken.