Heya!
This is probably possible using
BIS_fnc_crows, albeit slightly convoluted. Hmm. This is how I'd suggest you do it:
First, add the Functions Module to your mission (F7-Modules). The crows function needs the Functions module to work.
After that, add an eventhandler to any unit you want to spawn crows around upon death (in their init fields f.e:)
this addeventhandler ["killed", {sleep 120; _n=[(_this select 0),20,8,20] call bis_fnc_crows;}];
This will spawn 8 crows 20 meters around and 20 meters in the air around the dead person 120 seconds after they've died. I think. Untested, but it ought to work. Give it a try!
Wolfrug out.