Some things that are killing Tawny Owls are rat or mouse poison; when a rat or mouse eats poison and the owl eats that rat or mouse it gets poisoned and is most often ether killed or gets very sick. Cars are another problem sometimes, especially along busy highways. Losing their habitat is another big problem. This is a problem that effects a lot of animals, they loose their habitats for a number of reasons, the most common of which is deforestation.