I could list a billion things that bird is sensitive to! Its crazy! Haha. But when working for a facility there are many things at play with how things are handled or done.
Hopefully with my bird at home it will not get to this point, but a good conversation piece. When a bird if that sensitive, is it the best course of action to desensitize? I have seen birds especially of high intelligence, Harris and Turkey Vulture pick situations that can 'scar' them from a certain handler, not forgive easily or at all, and sometimes just decide they don't like a certain handler... I've seen this even in a gry-lanner falcon, who would come to three other handlers gloves, (even me who was new) but not one other handler. And would sit and do just horrible lure flights with them despite low weight. Haha
Is a sensitivity sometimes attributed to the birds previous history or maybe personality than handling techniques? (Though I'm not saying how the Harris has been worked with has encouraged pickyness)