While I am still in Minnesota (in both a Flood Warning and a Winter Storm Warning ~ that's Minnesota for you) I have been keeping updated on YNP and what is happening there. I have read that bears are coming out of hibernation. Just a couple weeks ago a grizzly bear was spotted fishing in the Yellowstone River by Tower.
The only road in the park to remain open year round is the road between Gardiner and Cooke City. The plows are now starting to clear the other roads, all 220 miles of roads. This can take an extraordinary effort as they have to clear roads where there can be 14 feet of snow on them, some with 40 foot drifts. The last area in the park to be plowed is Dunraven Pass, just north of Canyon. That won't even be plowed until May.