TLDR;
Negative is more bird.
What an odd thing. I discovered a link to this slider trainer yesterday, and found not only was it pretty easy to get set up, but it trained rather quickly on my 4090.
https://github.com/p1atdev/LECO/tree/sdxl
I replaced chicken with 1girl, then ran the thing as -6 and behold, we have a bird generator. I added and tinkered with some tags, and we have a highly potent birb slider. I'd say this experiment was enough of a success to actually make a real slider.
Suggested;
-6.0 for more bird
1+ for less bird