for Poacher Panic by Jan Burchett and Sara Vogler
"Twins Ben and Zoe are miserable after being left behind while their parents head to Africa for a veterinary adventure. But almost immediately after their parents depart, Dr Stephen Fisher, a famous zoologist, recruits Ben and Zoe for an adventure of their own! Soon, the twins are on their way to Sumatra to rescue a tiger and her two cubs from a gang of vicious poachers."
Publisher description retrieved from Google Books.