A new report from animal advocacy group Zoocheck says animals at the Greater Vancouver Zoo are suffering from a lack of enrichment in enclosures that are too small.

The report was commissioned by the Vancouver Humane Society and calls on the zoo in Aldergrove to improve conditions for its animals.

The zoo houses about 600 animals. Some, such as giraffes, hippopotamuses and tortoises, are living in "barren, under-sized" enclosures that make it difficult or impossible for them to engage in natural behaviours, the report says.

The raptor exhibit does not allow birds such as owls and hawks to fly and the Siberian tiger has worn a path along the fence line of its enclosure because it paces back and forth every day, said Peter Fricker, communications director at the Vancouver Humane Society.

"The animals are suffering from frustration and boredom due to captivity. They're showing signs of that frustration by exhibiting repetitive behaviour such as walking back and forth along the fence line or chewing at bars and fences," he said.

"There is not enough stimulation for the animals."

Zoocheck researchers visited the zoo over the past two years and recorded and photographed what they saw to create the report, Fricker said.

The Greater Vancouver Zoo did not return CBC's requests for comment. It has not responded to the report, Fricker said.

The report found that none of the animals housed in the vivarium, including reptiles, amphibians and mammals, have access to the outdoors or natural sunlight. The report says that most of the reptiles were "inactive" or demonstrating repetitive behaviours.

Furthermore, while most exhibits had furnishings and objects such as rocks, branches and leaves, some appeared to serve only a "decorative or cosmetic function."

Zoos cannot replicate conditions animals would have in their natural, wild habitats, Fricker said. But there are things zoos can do to alleviate boredom and frustration for the animals, he added.

Peter Fricker, communications director at the Vancouver Humane Society, says the report shows enclosures and habitats at the Greater Vancouver Zoo are restricting animals from engaging in natural behaviours. (CBC/Felix Levert)

This includes changing the surroundings in an animal's enclosure regularly, adding features and food puzzles, hanging food in trees or hiding scents in an enclosure.

The Greater Vancouver Zoo has made efforts in the past to improve conditions for the animals, Fricker said. This has included increasing the size of some enclosures and providing more enrichment.

But he says the fact that animals continue to show signs of "boredom and frustration" shows not enough is being done.

The report recommends the zoo increase environmental and behavioural enrichment for all of its animals, enlarge enclosures and stop keeping animals that aren't suited to B.C.'s climate.

"We don't understand why it makes sense to have a giraffe living on the West Coast of Canada," Fricker said.

"The climate doesn't suit them, and the enclosure's not very big. They would normally have a wide space to roam in the wild, they don't have that in captivity.

"They just can't live the kind of life they've evolved to thrive in."