Being small and warm-blooded, birds need to eat frequently to keep their energy levels up so they spend much of the time on the look out for new food sources. They will fly around or survey the area from the tops of trees constantly searching for anything that could be a potential new source of food.
Although some birds such as parrots, kiwis and vultures have a good sense of smell and will locate food using their olfactory glands, most birds use vision to find food. And because they spend so much time searching for food they become quite good at it. Birds also have good memories which helps them remember where food may be or look out for changes in the landscape that may signal food is about.
Birds may even be able to recognize bird feeders, not because of evolution, but simply because they are familiar with them. They may also start to learn the routines of people putting out food in their garden – have you ever gone to put out some food in the morning to find a bird is already waiting for you?
Once a bird has found a source of food, it may call to its mate or if there is plenty to go round to other members of its flock. However, if other uninvited birds turn up then they may begin fighting over food and the threat calls can alert other birds that something interesting is going on so they will join the party.