chameleon
Chirping
So I found the breed standard for Koekoeks finally, and it turns out they get pretty big. They are a bit bigger than New Hampshires, with roosters reaching up to 4.5kg and hens up to 3.5. They are also supposed to have yellow legs. I had a closer look at my chicks' legs, because the light wasn't great when I took the photos. They are mostly orange, but they're closer to yellow in some places, especially on the back of their legs and their knees, so I did some more research on leg colour. From what I can tell there is no such thing as orange legs on a chicken. These appear to be the recognised colours:

I have found it mentioned a few places that leg colour can change as they mature, so that might explain the difference. Hopefully they turn yellow, because otherwise they aren't pure Koekoeks.
I have found it mentioned a few places that leg colour can change as they mature, so that might explain the difference. Hopefully they turn yellow, because otherwise they aren't pure Koekoeks.