Fallen squirrel nest?

Look what landed on the sidewalk next to the Stick Library. I'm pretty sure it's a squirrel nest.

And I'm no animal scientist or forensic specialist, but I think that's a dried-out squirrel skull there. Making me suspect that the nest fell when its inhabitant was no longer able to maintain it after succumbing to natural causes.

However, I should add that while the Stick Librarian acknowledges that my theory could reflect reality, her wider experience and exposure to the world of crime leads her to suspect that other squirrels took action against the inhabitant of this nest causing their demise and the destruction of their home.

I should note that while I did not do a comprehensive study, I did turn over the detritus a bit with my snow shovel and found no other bones, but did find some furry fluff in with the leaves and twigs.

It was only a few years ago that I got curious about the clumps of leaves and twigs we'd see up in the trees. That's when I learned they were probably squirrel nests, and I was surprised to also learn that the nests usually only house one squirrel except when it's a mother and her babies. It seems that squirrels aren't really that companionable and when you see them interacting with each other, they're not playing, they're fighting.