Excavate -to make hollow by removing the inner part; make a hole or cavity in; form into a hollow, as by digging
A pair of chickadees were busy excavating a nest in a small tree at Rondeau yesterday.
Not many birds migrating through yet so it was nice to have something to watch.
According to Cornell Lab of Ornithology every autumn Black-capped Chickadees allow brain neurons containing old information to die, replacing them with new neurons so they can adapt to changes in their social flocks and environment even with their tiny brains.
Not sure how Cornell knows that.