Ticks

Firstly, this is what a tick looks like! Check it out.

A single tick is generally not going to cause any harm to wildlife, unless it is obstructing an eye or on a very tiny creature. It's best to leave it to drop off by itself, this minimizes the risk of leaving the head of the tick buried in the creature where it can cause an infection or abscess.

Huge clusters of them however will cause issues and it's best to have a vet or rescue centre check them over.