Jizz (birding); the immediately recognisable characteristics of a bird or other organism.
Sean Dooley described jizz as “the indefinable quality of a particular species, the ‘vibe’ it gives off” and notes that although it is “dismissed by many as some kind of birding alchemy, there is some physical basis to the idea of jizz.”
Good question, I only texted him about it. I assume like “gist” without the “t”.