Yellow Napes are a sub-species of Yellow Crowns and there's several subs of yellow napes(YN) as well. YFs tend to be smaller with lighter colored feet and beaks than YNs which have yellow further down their neck (nape) and with a grayer colored beak and feet.Most yellow Crowns have yellow starting at their beak back to their crown.Most yellow napes have green starting at their beak back to their crown and yellow on the nape,but not all !!!! some have a few yellow feathers right at their beak and then green ,and some have almost no yellow at all on their head or neck. As with all of the sub- species of Yellow Crowns,older more mature birds tend to turn yellower as they age. I have a 40 yr old parvipes Yellow Nape that has turned so yellow that she's starting to look like a DYH, she even has a yellow ring all the way around her neck, But she is a wild caught bird and i know where she came from, (the tree).Other wise you would think she was a hybrid.