Currently, about 50% of all species in Namibia are of some conservation concern. Historically, large game species were vulnerable to hunting and poaching, while other species, such as large mammal predators were vulnerable to habitat conversion to agriculture, leading to local extinction and numerous threatened species. Over the past 200 years, economically valuable game species, such as zebra or lion have experienced a 95% reduction of their former range in Namibia and species, such as elephants and rhinos experienced population reductions to sizes as low as 50 individuals. Although exact numbers are unknown, it is estimated that at least 10 mammal species once known to be in Namibia are no longer there, and are assumed to be locally extinct.