Everybody is feeling anxious as the zoo’s new young critically-endangered Sumatran tigers are introduced to each other for the first time. There is also a Royal visit as Prince Philip opens the zoo’s new £4 million Tiger Territory enclosure. The staff are forced to act quickly though after the tigers start fighting. At Whipsnade, Jo Dodds is training Nicky, an adult male chimpanzee, ahead of a major medical operation. Head of birds Adrian Walls meets eight new Humboldt penguins.