A big dog in a small body so they need more exercise than larger dogs (or think they do) and have an attitude to match. Their bravery when faced with larger dogs reflects their mental image of their size.

Jack Russell Terriers are ...

A hunting dog with the skills to make them excellent hunting dogs - tenacity, ability to follow a scent, a strong urge to explore and dig holes

A dog that wants to be underground, following a scent to locate and harrass their quarry until they are dug out or the quarry bolts.

In a modern home the Jack Russell’s instincts can be sublimated into a range of energetic activities. They can become a fiercely possessive protector of possessions and family, the can become keen gardeners (the digging part anyway), enthusiastic chasers of cars, loud barkers at postmen.