Canary in the coalmine

Make a load of canaries similar method to owl template / dress as human canary make a giant canary gather with groups associated with clean air / end fossil fuels etc - play canary bird song - make some fake coal carry on site in sacks - people in black suits throw coal in front of canaries - let off black smoke flare - canaries fall to the ground as a die - birdsong fades to silence. Can be used for end fossil fuels outside specific associated locations.