In this photo, one of the black squirrels is lying such that its head is sticking out upside down, while another black one, which had just left the cavity, is clinging to the trunk. There was a lot of activity around this cavity and it was quite amusing to see one or another squirrel enter by putting a paw on the head of whomever had their head sticking out, and pushing down firmly in order to make room to dive in as well.