Animals are more active early I the morning and late in the day as opposed to mid-day when the light is harsh and temperatures are higher. Therefore you have the best chance to capture images that are dynamic at these times. Cameras that perform well (little noise) at higher ISOs are beneficial when the light is low and yet fast shutter speeds are still required.
Careful observation of your subject over time is the key to capturing action and behavior. Alterations in body posture, shifting weight, and adjustment in muscle tension (whether noted cognitively or sensed subliminally) can suggest some change in behavior. For instance, shifting of body weight of a resting animal may indicate it is ready to stand or possibly stretch.
Birds stretching or flapping wings can often precede flight. Sandhill cranes lean forward before flying. Herons often bend knees and stretch out neck before flying. Seabirds landing on rocky cliffs often employ their wings to provide stability. Birds bathing typically splash while cleaning feathers and then shake off the excess water.
Chattering and agitated movements within a flock of birds frequently precedes the arrival of more members of their flock, the departure of birds, or the approach of a threatening predator.
Photography during breeding season is often rewarding since activities increase – turkeys strut, elk lock antlers, deer mark territory, etc. Nurturing behavior between adult and young often results in touching photos.