and I didn't even get Tit (40% guessed- is that a real thing? Do they hang out with blue-footed boobies?), Tern, Loon or Auk... but I got Ibis, Lark and Kiwi.
I think regardless of numbers of letters if I would ask people to name birds but no raptors, it would be one of the first 5. (Though we call it koolmees :) )
Maybe/most likely the difference between the USA and Europe. I think people from the US would think much sooner of jay for instance than people from around here.