In the real world you some times notice enemy patrols or get noticed because they scare away wild life like smaller birds.

In Zeus when you use Modules_Animals_seagulls. They start on the ground, before they fly up. I think that would be great to use as a "mine".
You place a "crow mine" in a forest. They start on the ground, but when a AI or Player gets too close they start flying up just like they do in Zeus. Maybe even landing again after a few minutes if the area is clear again.

Giving other people a chance to detect whoever triggered the flight effect of the birds and adding to milSim wildlife and realism.