There is a special danger for a cat who is jumping to a particular surface. Cats often jump onto small spaces; for example, a ledge. Before jumping they will move their heads from side to side to get a precise fix on the distance and landing zone. By moving their head they can re-evaluate the measurements through their binocular vision. Binocular vision (the use of two eyes) provides precise depth perception which is the ability to see the world in three dimensions and to asses the distance of an object. Of course humans have that ability too but we don’t have the jumping skills.
Some of the jumps made by cats require absolute precision on depth perception. Cats rarely fail with respect to landing precisely but they can fail in respect of noticing what is on the surface to which they are jumping.
If there is a sharp object sticking up out of the surface and the cat is looking right down the spike – meaning all that the cat sees is the very tip of the spike but sees none of the length of the object – she can jump right onto the sharp object. If all the cat sees is the tip of a spike she receives no information about the depth of the spike or sharp object. It becomes two dimensional and part of the surface onto which she is jumping.
This is almost certainly what happened to a New Zealand cat who jumped onto a the narrow top of a fence from the roof of a bungalow. Or, perhaps, in this case the spike merged with the background.
One of the pillars of the fence extended beyond the top edge of the fence and when she made contact with the landing zone the spike went straight through her.
She survived – cats often do because they have nine lives. She could not move because she was literally pinned to the spot. She cried out and eventually the fire brigade turned up and cut off the fence post and removed the cat and post together whereupon an SPCA manager gently removed the spike in situ before she was taken to a vet.
It is rare that such an accident happens but cat owners should be aware of the possibility if their cat is of the more adventurous kind.