Ants are social insects, which means they live in communal colonies together. They work together to maintain and grow the nest. They communicate by using a series of chemicals called pheromones. Once they find something they like such as a piece a food they lay down more and more scents to indicate to the rest of the colony what they found. Soon reinforcements will gather and harvest their found bounty.
Take a look at the damage that carpenter ants can create to trees. This hollowing will definitely compromise the integrity of this tree. Having nests like these can lead to all sorts of pest problems for the home. Carpenter ants have a large range they travel, meaning the nest can be located in a tree outside but they are traveling into your kitchen for a snack everyday.