Druidic

Druidic is a cultural cipher-language used by druidic circles wherever they may be found. Druids utilize their familiarity with nature to send and receive messages, whether they were made by a druid or by nature itself. Only those closely attuned to nature can tell the subtle differences between natural occurrences and a Druidic message.
While some Druidic signals depend on the environment that the druid is familiar with, others are understood by all druids. Below are a few examples of common Druidic signals:
Long-distance: A druid can whisper or whistle a message to be carried by the breeze. While this method takes a while to deliver the message, it is one of the most effective long-range communication forms for druids.
Long-term: A druid might find a message hidden underneath the bark of a tree giving information about the area or its denizens.
Instantaneous: Druids might copy a bird's calls to communicate over short ranges to give quick and clear messages.