Summary: Giraffes, the world's tallest mammal, are slowly going distinct due to the loss of their habitat and illegal hunting. The overall population has decreased by 40% over the last 3 decades. Currently there are less than 100,000 alive.. There are 9 subspecies of giraffes: 5 of which are declining in population, 3 that are increasing, and 1 that is stable. Derek Lee, an ecologist, said that giraffes could greatly decline if no one does anything to help the animal.