Before the telegraph, pigeons were used to carry messages. The pigeons are called homing pigeons. These pigeons are particularly good at remembering where they live, and finding their way even when they’ve been transported tremendous distances away from it.
They do this due to their ability to detect and orient themselves based on magnetic fields. To train a pigeon to deliver a message, you have to take them from their home, put them into cages, and transport them to your location. When you want to send a message, you strap a special lightweight case to the pigeon’s leg, and you let the pigeon go. It simply flies home, that’s all. Pigeons don’t fly anywhere else — only home.