A strange feeling of unease may prevail upon "the small army" as a flicker of a shadow out the corner of an eye, keeps watch.
The shadow does not appear hostile but keeps track of the interlopers and their movements. It is unseen without exceptionally good eyesight and hearing and can only perhaps be sensed by a deadening of noise in certain places and vaguely-off lighting in others.
When dusk falls, a tiny bat flits over the canopy and vanishes into the night. The shadow seems to remain.