Identification is straightforward: bulky, gray chest/upperbody along with the burnt orange undertail coverts. Vocalizations are distinct. Mr. Swarth describes (1922, from Life Histories of North American Wagtails, Shrikes, Vireos, and their Allies; author-Cleveland Arthur Bent, reprint from Dover 1965) the voice of the Bohemian as a "buzz...coarser...as a series of slightly separated notes". And yes, they are 'garrulus' calling most of the time from flight or day-time roost.
Invariably, because of their flock size and vocalizations, merlin (Falco columbarius) isn't far away.
|Merlin (Falco columbarius)|