Pandas Kai Kai and Jia Jia have attempted to mate for the first time, said the Wildlife Reserves Singapore (WRS) on Tuesday. Although the 40-minute session on April 17 did not appear to be successful - which is typical for first-time breeders as they may not know how to mate - it was still a cause for jubilation for caretakers at River Safari as the critically endangered bears are notoriously difficult to breed.