Was it paired or with squabs?
I have no way of knowing immediately. I will have to do the process of elimination. With close to 40 birds and the balance of them snow white it may take awhile before I find out who was lost.
No more 1400hrs flights for a time plus I will keep them confined to the loft for a few days. I have been flying them a bit too regular as of late it was bound to happen. Hawks have enemies too they best be ware I can think of two one of them being crows.