At times it is better to hunt them after the first snow or when there is snow on the ground. Snow kills off the grass hoppers and other natural food they would normally eat. Hence, they will be a little more eager to come to a distress call as they will be a little more hungry, Also, they have to eat more often in order to keep warm. Try to find an area that has not been over called already. DO not forget, you can howl them in just as easy... they will try to protect their feeding areas now also.