Blame the Coal Tits.

I know, from personal observation, that my visiting crows are prone to secreting food around the place for future reference; it seems Coal Tits do the same. It's the only logical way to account for the VAST number of seed they make off within any series of visits; and the number of rogue "Tournesol" which appear in places where I can NOT possibly have accidentally dropped a seed.
I have, honestly, never tried to grow one for height; or for that matter at all, yet they keep cropping up.