Interestingly enough, I just found this about crows:

One curious feature of the behaviour of crows is their seeming
capacity to hold 'courts' at which, by numerous accounts, they
pass judgement and carry out summary execution of such of their
numbers as, for some mysterious reason, they consider deserving
of it. As Edward Stanley, the Victorian naturalist put it:
In the Northern part of Scotland, and in the Faroe Islands,
extraordinary meetings of crows are known to occur. They
collect in great numbers, as if they had all been summoned,
for the occasion; a few of the flock sit with dropping heads,
and the others seem as grave as judges, while others again
are exceedingly active and noisy; in the course of about an
hour they disperse and it is not uncommon, after they have
flown away, to find one or two left dead on the spot.
Another writer (in Dr Edmonston's "Shetland Isles"), says that
these meetings will sometimes continue for a day or two, before
the object, whatever it may be, is complete. Crows continue to
arrive from all quarters during the session. As soon as they
have all arrived, a very general noise ensues, and shortly
after, the whole fall upon one or two individuals, and put them
to death; when this execution has been performed, they quietly
disperse.