Belfast City Council has heard a proposal that could see the animals at Belfast Zoo evicted if given approval.
Sinn Féin Councillor Conor Maskey's motion for Belfast Zoo was outlined on Monday evening.
He says he wants to transform the site into a "world class visitor attraction" which would not include what he describes as the 'wrong' and 'unethical' practice of displaying caged animals.
He proposes to return all non-indigenous animals like gorillas, lions and giraffes, to their natural habitats in a phased approach.
We can concentrate on the conservation element of things rather than concentrating on our entertainment. So keeping zoo animals in cages that they’re not used to, simply for us to be entertained is an element of the zoo that we believe it wrong, outdated, unethical.
The motion has caused upset among zoo staff and conservationists.
Belfast Zoo is home to over 600 animals and there are concerns about how they could be rehomed.
SDLP Councillor Carl White said: “What are we going to do, return them to areas they are no longer safe? They’ll be hunted by other animal predators or by human predators. I think we need to remember the important work that’s being done here and work to make sure that Belfast Zoo becomes recognised as the global expert in animal welfare that it is.”
For zoo staff whose jobs are at risk, their only concern is for the animals.
GMB regional organiser Alan Perry said: “What would happen to them [the animals] rather than themselves and potentially their jobs, so that’s where their focus is and it shows you just how professional these guys are and I think that actually gets lost in the article Councillor Maskey put out.”
The move has also been criticised by The European Association of Zoos and Aquaria, the body who manage the movement and welfare of zoo animals.
A statement said: "Belfast Zoo's record on conservation of species is impressive and a credit to the people of the city...
"Mortality rates of reintroduced animals will be unavoidably high... up to 70% in some cases...
"Mr Maskey's plans show no understanding of these principles and outline no intention of engaging with experts in the field."