The territorial Animal

BBC recently had this news item on how a herd of goats managed to master a cattle grid laid to prevent them from coming into human settlement eating plants and flowers laid in a cemetery. Goes on to prove how Man is the biggest territorial animal of them all.
We have carved out large portions of Earth, destroyed animals and trees we could and built our own forests of concrete. We got in a few cosmetic animals just to remind of our ancient past, popular choice being pack animals that look up to the masters as the pack leader. And we have built our own structures to draw boundaries of personal space.
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Makes me wonder if man has the right to decide to 'cull' animals just because they come and eat flowers we put on our dear one's graves, people already no more living? Here probably the goats are no threat to life and liberty, just a cosmetic nuisance. I can understand the urge to kill for food but does nuisance deserves death?(In case of mosquitoes, yes I think it does, see my earlier post on this but we digress).
The thing is that nearly all other territorial animals defend their territories typically either during feeding or mating times. Most often these territories are those that give great food advantage and where having a crowd with compromise food security. But with humans its often a case of power/wealth projection. I wonder how sustainable would this be over years. What happens when the human population reaches like 8 billion?