With the reintroduction of wolves and the resulting decline of elk populations, balance has returned to the Yellowstone ecosystem. In the absence of overpopulated elk herds, Willow, Aspen, and Cottonwood trees, which are a critical food source for moose in the winter months, now flourish.
 
In the winter of 2018, twenty-one moose could be seen at Round Prairie in the north east corner of the park. All the moose in this photograph were males (bulls) but several had already lost their antlers for the winter months.