Its a winter kill but can't remember the term for it in this case. Not all turkeys in the area died but those did due to this..... The kill like that in the winter is from basically dehydration and freezing. When it gets super cold they roost like that and huddle up to keep warm and will stay in a "hybernation"like state to conserve energy cuz flying down and up and digging for food, eating snow for water, and regulating their body temp takes more energy than they can take in in super low temps. Until it warms enough for them to start feeding, and eating snow, and such again they will stay in this state and if it lasts to long for their body condition, eventually they will all tip over dead at relatively the same time. Once they start to go the rest follow as they lose body heat from the other who have died and fell. It happens quite often and usually doesnt kill all the birds in an area. I've heard of some pretty large numbers of kills like these before. Heardlast winter of3 trees within about40 yards of eachother withabout 50 birds layin dead. Seems like it happens more common in highly populated areas prolly cuz food is an issue when winter gets tough on them. Another one of natures lil ways of population control I guess. WCL