Instinctive behavior is a behavior that is exhibited by all members of a species, without being learned.
An example of instinctive behavior can be seen in rats. My sisters have had ten pet rats over the last 8 years and every single rat reacted the same way to a loud noise; they all froze. Every one of the rats had the instinct to freeze when startled, a behavior that is instinctual to every member of their species.
This is example portrays instinctive behavior because the behavior of freezing in reaction to being startled is exhibited by all members of the rat species, without their learning it.