The bird you learn to recognize changes the meaning of the same old tree.

Knowledge changes what is available to your senses. Once you can tell one bird from another, a tree stops being scenery and becomes a place where particular creatures do particular things at particular hours. Nothing outside you has altered; the amount you can perceive has.

Learn the names of five things on the route you walk most often, whether birds, trees or buildings. The gain is not the naming but everything you start noticing afterwards for free.