In his book "Seahenge: Life and death in Bronze age Britain" Francis Pryor (an archaeologist) identifies all manner of shapes and sizes of henges and enclosures, and relates them into a systemic ritual landscape tradition based on excarnation and funerary rites within small clans and familiy groups. These were for human use, and had a religious/magical significance. The surrounding land would certainly have had animal pens and paddocks, and fields enclosed by dykes, ditches and hedges, but I don't think the features you're talking about would have been defensive measures against wild animals. The main predator of animals would have ben organized rustling raids by neighbouring clans (especially their hormonally challenged young men).