This has been something that I haven't been able to grasp lately. How do we determine how much space a captive animal needs? I'm not sure there is an answer to this, however zoos must base their enclosure size off some sort of observation/facts. For example, will birds of prey like Griffon vultures soar miles in the sky if there is no need - they are soaring in search of carcasses, but if these carcasses are provided to them, what is the need? This is the same with every species since animals move in search of food/mates/water, however if all these needs are catered for in a limited space, then wild animals will simply stay within this space. This can be seen at bears in campsites, where they can live off food provided by campers and therefore do not need to travel in search of food. Therefore, is the argument that "zoos do not offer enough space for animals" really valid, if even wild animals will not move if they do not have to?