Love this concept, squirrels are so cute when they prepare for winter. :3
I have just a couple of things that might help with your piece.
The first thing that stood out to me was the bird. I felt it was out of place, however, I think it might have just been due to his line of vision. It's taking the viewer eyes away from the piece when we follow it.
Hope you don't mind I did a quick draw over to demonstrate what I mean.
I felt if you changed its line of vision to maybe be looking at what they're gathering, then it will engage the bird into the piece.
Another thing I noticed was that the squirrel parent seemed to be admiring the "food, gathering materials" for itself. Almost like Gollum from Lord of the Rings "My Precious" Haha. I felt that if the parent squirrel turned towards the babies as if it's offering it to them then it would look more like a family preparing for winter.
This combined with all the critters line of vision, allows the viewer to understand better what is occurring within the piece.
Awesome job, can't wait to see as this piece progresses through Slowvember!