Well I don't think anyone saw that coming. In a new interview Hideo Kojima casually mentioned you can build a zoo in your Mother Base like it was no big thing. You can also attack other people's bases online.
It certainly explains that screen and why you would bother ballooning animals out of a battlefield.
MGS5's Mother Base lets you set up and create your own base of operations, either in-game or via a mobile or tablet device. Speaking with CVG Kojima outlined, "different gameplay elements", such as collecting diamonds and animals. The latter letting you "make a zoo". The Fulton Recovery System used to balloon away prisoners/recruits and animals can also recover vehicles and other gear to help build and arm your home from home.
Kojima also outlined the creation system and the ability to attack your friend's bases online:
"People who want to create a Mother Base in a very detailed way will be able to design it through the interface, or using their smart device". I cannot talk too much - I'm being watched, but for people who saw the presentation, it ends with your Mother Base being attacked. People can infiltrate you, and you can infiltrate other people's mother base."