Kate Humble and Ben Fogle return to Longleat Safari Park for another spectacular summer series following the fascinating stories of the exotic animals and the keepers who look after them. Today, Kate and Ben find out why love isn't always easy - even for animals.We have been following the incredible story of the birth of Europe's first southern koala joey. As koalas are now classified as endangered in parts of Australia, the park's breeding programme has never been more important, and with this in mind, the keepers have decided to introduce successful dad Burke to a different female, Maisie. But they're both feisty animals, so it's not clear if they can even live together, never mind mate. A few days after they are introduced, the keepers spot some surprising behaviour - but is it good news?There's also some unexpected behaviour in Wolf Wood. The keepers have noticed that the wolves have been digging a lot recently, and this could be a clue that the pack is on the brink of enormous change. Could the mother of the pack be pregnant? Wildlife cameraman Hamza takes the chance to get a closer look at the pack's dynamics and check in on the mum-to-be. Will he find more evidence of pregnancy?Ben gets an update on three-year-old tiger Yuki, and Kate mourns the loss of one of the park's legendary animals. Meanwhile, Megan continues to find out how the keepers in the park maintain their animals' great condition. Today, she helps with a health check on two new arrivals - a pair of royal pythons.