White settlement of their home, Mauritius, introduced predators and diseases to which they had not been previously exposed. Their habitat (forests) was also significantly reduced. Also, being flightless and a bit cumbersome they were easy prey to hunters (although the meat was said not to be very good). It's a classic case of human intervention in the natural environment.
Fortunately Mauritius has survived the colonisation by various European nations and is now an independent, relatively trouble-free destination with a welcoming population. It has one of the highest per capita incomes of any African nation. about 7 years ago