Miche, you know I was saying about Bella and her similar squirrel problem - I've been using a clicker lately as although my "Bella Squirrel!!!" thing works to get her to come in the right direction (towards me) it doesn't get her close enough to put on the lead. So what I'm doing at the moment is that if she is in the middle of a squirrel fest but happens to come anywhere near me, I click - to begin with I had to click 3-4 times in quick succession and that was enough to get her to come to me for her reward. She's now a bit better, one click usually does the trick. I'm not trying it when she's actually at the quivering wreck (in sight of a squirrel) stage, just when she's running from tree to tree looking for them. But it is definitely improving things.
In fact in the park today (admittedly no squirrels but as I've said she'll happily spend an hour looking for them) she got bored of looking for them and actually started doing completely unprompted offlead healing, looking up at me to see if she'd get a click and treat (which she most definitely did!). Obviously it's not squirrel season at the moment but she's still obsessed, she is constantly on the lookout and if she sees one on the whole walk that is ALL she thinks about, no playing with other dogs - she'll actually go and sit off on her own to be able to pay proper attention to potential furry grey creatures.
And she's normally a very sociable girl!
So a clicker might help although I know you've said he's not food motivated, whereas Bella definitely is. But if you maybe combined the feathery toy idea with a clicker then you might be onto something....?