Cats chase mice, geckos, snakes and other small animals for a number of reasons, all due to their natural instincts and behavior. Here are the main reasons for this:

1. Predatory instincts:
Natural: Cats are carnivores by nature. They evolved as hunters, and this instinct is inherent in them. Chasing food is part of their basic instinct, which leads them to hunt and track small prey.
Hunting: Cats usually catch prey using hunting tactics, such as stealth and silent movement. They can hide and then jump on the prey at the right moment.
2. The need for food:
Diet: Mice, geckos and snakes are part of a cat's diet. Chasing small animals is a way to get food. Cats are hunting animals, and they need to catch their prey to survive.

3. Curiosity:
Cats are very curious by nature, and they tend to explore their surroundings. When they see the movement of a small animal, it can be a call to action. Curiosity may drive them to chase the prey to figure out what it is.
4. Game:
Young cats may chase mice and gooks not only out of need for food, but also out of a desire to play. Chasing and hunting are part of their game, and they use their instincts to reproduce hunting behaviors as well.
5. Defense of territory:
Cats are territorial, and if they spot a mouse or snake entering their territory, they may chase that animal to defend their territory. This is an intuition to protect their resources and personal space.

6. Previous experiences:
Cats that have learned to catch or fight mice or other small animals may feel more confident in this action. Positive experiences from the past can motivate them to pursue prey again.
7. Social customs:
Cats sometimes behave according to their social dynamics. If a cat sees another cat chasing a mouse, it may join in and chase too, to participate in the social action.
Summary:
Cats chase mice, gooks and snakes out of natural hunting instincts, need for food, curiosity and desire to play. In the absence of available food, they may rely on these abilities to survive. The connection between their behavior and their natural and evolutionary behaviors is what motivates them to chase small animals.