Roadkill ones don't count mind 
It's like the 'ever seen a baby pigeon?' question. We know they exist but whose ever seen one?
I walk through the park every morning and I'm surrounded by squirrels jumping about and climbing trees, there's tonnes of 'em, however despite the masses, I have yet to chance upon one toe up in the grass dead as a doornail.
Where do squirrels go to die?
Perhaps maybe....they don't die!?!?!? Squirrels could be the fountain of youth!
I'm thinking an experiment in squirrel blood drinking is in order!
Munzly
In fact, when a small animal feels death coming upon it it crawls away into some hidden nest, lair or hole in the ground and dies there. Decomposition is rapid and the ants carry away the small bones. Sometimes the rats or a fox find the cadaver and scoff it for a passing snack. So you see, nature with the help of bluebottles etc. sorts it all out with ease and efficiency. It's only people who clutter up the place with gravestones, mausolea, pyramids etc.
... but you knew all that didn't you?