My Druid wants to warn any unsuspecting travelers from taking a shortcut that leads to a hazard that the party is dealing with. Can he use animal messenger to do it?
The animal messenger spell description states:
You specify a location, which you must have visited, and a recipient who matches a general description
Does this language allow my Druid to specify something like, "Go to the crossroads and tell the first person who comes by, 'Avoid the western route'"?
The examples given in the text all imply that the messenger searches for the recipient and immediately gives the message, and the following text implies that there is no waiting around by the messenger.
When the messenger arrives, it delivers your message [...]
The only limitation specifically mentioned regarding time is the 24-hour spell duration.