The look of resignation on this cat's face says it all. Fortunately, the owner of the cats knows of another caregiver - he heard about her from a cousin of his who spoke very highly of the caregiver. He kept asking about her earlier today.
She just spoke with him and he has agreed to sterilise the cats and perhaps relocate some of them. She also confirmed that he was agreeable to trying to adopt some of them out. If anyone knows a good owner who wants these cats, let me know.