We have had four squirrels die in our yard. We have two acres, very wooded. The only commonality is each one was found flat on its back, like they dropped from the trees. All in good shape, but hard to tell as with all the rain,they were all wet.
We feed the birds extensively here and use no chemicals in our garden. Can't figure out what's going on. We have a very inquisitive border collie and don't want her to be affected.