As we find out quite quickly, wizards in the Harry Potter world use owls for communication. Why owls?
They can attract unwanted attention, such as:
- At the very beginning when even the muggles noticed: "bird-watchers everywhere have reported that the nation's owls have been behaving very unusually today."
- In the second year, when Platform 9¾ closes on them, Hedwig attracts attention by screeching.
Why not use, e.g. carrier pigeons?