The sow has not come out of the den since the birth of her cubs in the very early hours of 1/31. We saw her outside for short walks and eating snow on the day before the birth.
Now, the cubs probably weigh around 2 lbs each. Their eyes are probably not open yet. They need their mother to stay wrapped around them to keep them warm and to let them nurse. The mother bear loses about a half pound per day as the cubs draw energy from her reserves through nursing.
It's miraculous to me that a mother bear gave birth in this small cave nestled in our woods, and now the family is holed up in that cave while the cubs develop. In all likelihood, we will see the cubs come outside the den for the first time sometime in late March or April.
There are bear biologists in Minnesota who know more about den life and cub development than anyone else. They have a website that even includes a video from a camera placed inside the den. It shows a mother bear interacting with her three cubs.
In Minnesota, bear cubs are usually born around 1/21. Our bear cubs were born about 10 days later than that so you need to add 10 days to all of the dates that they give for various developments in the cubs and mother. I talked with one of the bear biologists (Lynn Rogers) from Minnesota, and he predicts that our cubs' eyes will open around 3/15. The date that they first come out of the den will depend on how much snow there is by the den.
Here's a video including clips from the past 3 weeks that you can watch here or at Youtube. Although the bears didn't come fully outside the den, the cubs can be heard bawling, probably when they get cold or lose their lock on a nipple for nursing. Enjoy!
I expect that the next round of video clips will be very interesting because they'll include the mother and cubs spending time outside the den. I'm so excited to see what footage we get!