Grumpy elephant Thi is expecting a baby. The chimps battle for dominance. Red panda Nima gives her partner Jung the cold shoulder. And the meerkats prove they're not as loveable as they first seem.

Inseparable penguins Rud and Spike have been a couple for 15 years. But Rud's arthritic hip could be affecting his quality of life. The tigers move house, and a tarantula risks his life to reproduce.

The giraffe family have a new arrival. Frog keeper Pip creates a love den to try to get endangered frogs in the mood to lay eggs. And the aardvarks wreak havoc by night.

Boris the chimp takes a moorhen chick hostage. French crocodile François turns his snout up at British food. The keepers try to spark romance between turtles Raja and Aris. Plus: young penguins.

Female rhino Kitani is introduced to her new mate, Magadi. But rhino mating is a risky business. There's a surprise birth in the orangutan house. Plus: fruit bats, macaques and young jaguars.

A potentially deadly virus hits the elephant house. Will Chester's female zebras be interested in new stallion Mac? Plus: the bizarre world of the naked mole rat.