The collar for our dear 213, Spartacus, was found recently in the woods. This squirrel was first collared in Oct 2010, so he had about 20-21 months of tracking. He was certainly a crew favorite–and had quite a large range (I think ~14-16 acres or so). The collar was found alone and had no evidence of mortality. However, the tie that holds the collar around the neck was not entirely bitten through. So he either was eaten (my assumption), or had lost so much weight that he was able to slip out of it.