I would consider it to be these few weeks in January.
I hunt waterfowl on the prairie waters most every weekend.
The change I see at this time of year is how vicious and desperate the predation and scavenging becomes.
Most of the season I can recover a downed bird when shooting slows a bit, but in January any bird recovery will be a race.
In January I have had downed ducks stolen many times by eagles. I've had 4 hawks and an eagle circling a downed duck on the ice just like vultures. I've crossed an icy creek to recover a duck, took me about 10 minutes, all that was left was feathers. Coyotes will risk falling through the thin ice to recover cripples on the icy surface.
January is a lean mean season.