Members of the Order use their Patronuses to communicate with each other. They are the only wizards who know how to use their spirit guardians in this way and they have been taught to do so by Dumbledore (he invented this method of communication).
-- J.K. Rowling (JKR)
Sends a magical messenger to someone in the form of the caster’s Patronus.
References from the canon
- Dumbledore sent a message to Hagrid using this spell. He simply pointed his wand in the direction of Hagrid's cabin and sent the messenger without saying a word. Hagrid came directly to Dumbledore, which suggests that it is possible to retrace the messenger's path (GF28).
- Tonks sent a message to Hagrid to come get Harry at the gates of Hogwarts, but Snape got the message instead (HBP8).
- This spell is the method of communication used between members of the Order of the Phoenix, invented by Dumbledore (JKR)
- Cast by Kingsley Shacklebolt to send a message to the wedding guests at the Burrow; his Patronus is a lynx (DH8).
- Cast by Arthur Weasley to send a message to the Burrow announcing the arrival of the Minister for Magic (DH7) and later to send a message to Harry, Ron, and Hermione; his Patronus is a weasel (DH9).
- Hermione said she had been practicing and thought she could cast this spell (DH9).
- McGonagall cast this spell to contact the other three Heads of House just prior to the battle of Hogwarts; non-verbally, she conjured three Patronuses at once and sent them to their destinations, an impressive feat (DH30).
- Snape's silver doe Patronus acted as a "messenger" sent to lead Harry and Ron to the Sword of Gryffindor hidden in a woodland lake, however it did not speak. (DH19). Snape never used his Patronus to communicate with other Order members (BLC)