Observers are bots that, well, observe. They are usually found in wings with Transport drones and Hive Queens. These bots are unarmed and carry a mere 2cu of cargo, but are very fast and maneuverable. Because a wing will not respawn until all of its members have been destroyed, it is often necessary to hunt down and destroy the Observers in order to get the Transport drones to respawn. Observers are also responsible for scouting out new locations for Hive Bastions and for re-creating a destroyed Leviathan
From the desk of John "Incarnate" Bergman-- Collectors (Taken from: Design Wiki) These units function as the eyes of the Hive, guiding it to new resources and patrolling existing borders.