"Thestral’s can only be seen by those who have seen death," Draco said smoothly, "this has given them a rather unfortunate reputation of being bringers of bad luck, or an ill omen. This reputation is false: they can be extremely useful and are very intelligent - more so than the other winged horse species. Though they have been ranked as dangerous, this is mostly due to how misunderstood they are. Admittedly, they   are   capable of kicking your head in, but as is your common horse, so," Draco finished with a shrug.