Could be!! Certainly makes me sneeze my head off. I'm obsessed with keeping mites at bay and have DE everywhere! And I mean everywhere? Coop walls, perches, nest boxes, dust baths. I dust the birds with it too. Could do with shares in a DE company I think.
They could have done if you have found no evidence of a predator attack. We have chicken napping and dog napping from gardens over here in the UK. You can't have anything I tell you. They even go round nicking horses rugs of their backs in the fields.