After watching episode 2 of season six, I heavily suspect Partridge. He was hardly mentioned after his "death". Im almost 100% RJ's phobia has to do with pidgeons after seeing how Jane watched them. The description we got can't be trusted. RJ would know if she was recording it, he wouldnt do something to stupid without thinking. So basicslly take the description and forget about it. We all got distracted by the whistling, but that was meant to be misleading. There was a reason there wasn't anything about Partridge, RJ wouldnt give hints about who he truly is. 

But I could easily be wrong.