Small Animals
Small animals like birds, hamsters, gerbils, etc., can safely be transported in their cages in your car.  Just be sure that food and water sufficient for the entire trip are available to them.  The cage should be covered with something to keep the animals restful and quiet, but allow sufficient ventilation.  The only danger to these animals is drafts and extreme hot or cold temperatures.  So, take care when parking your car.

Fish
Transport each fish separately in a bowl or jar half filled with water.  If moving long distances, giving the fish away and restocking the aquarium at the new home should be seriously considered.  Fish do not travel well.

Dogs & Cats

Many dogs and cats, when transported by car, tend to get upset and nervous, even car sick.  Further, they are used to their schedule and must have regular rest stops, and be watered and fed.  If your trip is long, be aware that while some hotels provide pet facilities, others do not allow pets at all.  So, you should call in advance to determine which hotels are available to you.

If you decide to transport your pet by air, you will need a health certificate from your veterinarian.  Most airlines provide special shipping containers for pets, which are shipped in the baggage compartment.  To reassure your pet, place some item of your clothing in the container with him.  As well, consult your veterinarian for possible tranquilizers that might be used to ease your pets journey.