Carrier Birds

Carrier birds are the go-to means for the sending of messages quickly across Dormelia.
Through the use of lightning crystals, it has become simple to designate which postal aviaries a pigeon is to fly for a given message.

Utility

The integration of the medallion system has proven to pave the way for expanding communication across Dormelia as a whole.

Social Impact

The inclusion of crystals to the use of messenger birds and the resultant expansion of their networks have been a major boon for communications. News from one side of the continent can reach the other within a matter of days instead of months. Information is shared more freely across regions, leading greater exchanges between communities.

Access & Availability

Financially, carrier birds are fairly economical even with the integration of crystals to the service, with most being able to afford the service to send a quick message to a loved one.
Limiting factors, though, such as potential scarcity of homing medallions to a given aviary or birds can lead to bottlenecking of communications. Also, weight is a major factor where messenger birds are concerned with most aviaries instituting rules limiting the size and weight of parcel before it can be sent. These limitation have been somewhat alleviated by various species of birds being used (pigeon, hawk, falcon, etc.), though it still remains a concern.

Complexity

Over the years, the mechanics involved with the use of crystals and messenger birds have become quite streamlined.
At each aviary, a pigeon is fitted with a leather harness that houses both the message and homing medallion within a single unit. The medallion is secured in a clasp over the bird's breast where it can best influence navigation without interrupting flying capabilities. A capped tube on the back of the bird houses the message to be sent. The harness also contains a compartment for holding the crystal attuned with the sending aviary for any responding messages. All of these as well as the harness itself is secured using snapping fasteners to help maintain a more streamlined appearance and aerodynamic function than might be accomplished with buckles or other fasteners.
As for the medallion, each would be described as coin approximately three quarters of an inch in diameter. In the center of each coin is set a small lightning crystal, below which the coin is marked with which aviary it resonates with. The coins are casted using light-weight metals such as aluminum.

Discovery

Messenger birds have been used since even before the current Age of Dawn. 
The combination of said birds with lightening crystals came from the observations of the scholar Bernard Linseed. In a paper he penned on the subject, he noted how using a pigeon to send a crystal sample to a college routinely failed as the pigeon would simply fly to his study where he kept the original piece. After a series of trials with different birds and crystals, Linseed found that the birds would home in on the original lightning crystal from which the sample attached to their respective letters had been chipped off from.