There are 6 different types of food in the game. Previously these were shown with different arrows on the compass, but that was removed in a later version. In addition, the frequency has increased. So now it's enough just to fly around to find food.
Another way to find something edible is to land on a bin. Here you either get something to eat, in this case you can tell by the message on the right, or you get a branch that is relevant for nest building