Striking workers at the Toronto Zoo say they're ready to return to the bargaining table due to concerns about the welfare of the zoo's 5,000 animals.

The unionized zoo workers have been on strike since May 11, but recently made an "unprecedented" decision to open the picket lines after the birth of two clouded leopard cubs at the zoo.

The mother clouded leopard was showing signs of rejection toward the cubs, said Christine McKenzie, CUPE Local 1600's president.

She said the situation was beyond the capabilities of zoo management, who have been caring for the animals during the strike.

The union says it sent three veterinary technicians to treat and care for the cubs overnight, which are now believed to be safe and healthy.

CUPE Local 1600 says that incident and subsequent decision to temporarily break the strike has provided new motivation to return to the bargaining table. The union is also concerned that breeding programs for animals such as the endangered black-footed ferret will be jeopardized by the strike, which includes around 400 workers.

"The board has a responsibility to ensure that our animals receive the highest quality of care," McKenzie said. "That can only be achieved with our members."

Baby African penguins

The keepers of these African penguins are involved in the strike. (Toronto Zoo)

Dispute over job security, affordability

Zoo workers walked off the job on May 11, citing concerns over changes to certain employment clauses that could affect job security.

The union says one proposed change would eliminate a clause that guarantees a minimum workforce of 150, opening the door for a heavier reliance on private contractors.

During the last round of bargaining, zoo management said it made proposals addressing those job security concerns, but those talks broke off after a disagreement over affordability.

The city provides Toronto Zoo with an annual subsidy of $11.6 million.

Mayor John Tory says that funding has helped create excellent positions at the zoo.

"These are jobs that have a guaranteed pension, generous benefits and more job security than most people who live in the city of Toronto," Tory said.

In a statement to CBC Toronto, Toronto Zoo spokesperson Jennifer Tracey said the two sides are scheduled to meet on Wednesday.

"We look forward to meeting tomorrow with the hopes of reaching a fair and reasonable agreement with our valued union employees which would end the strike and re-open the Zoo," Tracey wrote.