Hanging close together or stacking game in a mass may cause heating. Skinning game in the field and then placing the carcasses in an insulated cooler between layers of dry ice is an excellent way to rapidly chill carcasses. The outer end of the breast bone is rather flexible in any young bird. Field dress the bird immediately. Wipe the body cavity with a dry cloth, paper towel or dry grass.
Moisture spreads bacteria which causes spoilage.
Cool the bird by allowing air to circulate in the body cavity. Hold the cavity open with a small stick to speed cooling. When the weather isn't cold, bring a cooler in the car to transport birds. When you get home, finish dressing the birds. A fully dressed bird can be more safely aged by refrigerating at 35 F for four hours to tenderize and develop flavor.