Whilst out doing big cat research I and other people came across a large regurgitated pellet, possible from a buzzard.It contained the bones of a mole. It was the largest mole I had ever encountered. Its skull and insectivorous teeth are obvious. Birds cannot pass solid waste in the same way as other animals, so it has to come out the same way as it went in.
If one looks on the trunks of trees especially oak and beech, one can find lovely little long shelled snails such as this bulin snail. There are so many different species and can be very tricky to identify.
A nasty smell like rotting flesh can often fool one(myself included)into thinking that there may be a dead animal near by, and frantic searching may prove fruitless. Look for the phallic looking fungus (phallus impudicus), it smells like rotting flesh to attract flies that visit the head and pick up spores to spread elsewhere.