This thread is about wild and zoo animals which voluntarily enter, stay or return to their exhibits. To show by examples, that animals do not understand nor desire 'freedom', but are strong materialists, going whenever there is food and safety.
A striking example is from Stuttgart zoo, because...
I just stumbled across this new zoo book, published last August. Anyone read it? The reviews are great.
https://www.amazon.co.uk/Zoo-Ethics-Challenges-Compassionate-Conservation/dp/1501714422/ref=pd_sim_14_1?_encoding=UTF8&psc=1&refRID=V85SZ3QXA1YGV8Y4ZG56