Genetics Help: I Know Both of these Phenotypes as Birchen: What's Going on Here?

[sjango]

I am asking the community for information regarding the genetics of birchen because I believe I still do not have an appropriate understanding. I am grateful for any and all input so thank you to everyone in advance.

First Hen:

Hen shown above followed by a rooster with very similar genetics.
I have always thought of them as birchen.

Second Hen:

This is another female with a different phenotype. I have been calling this birchen, or in this case red birchen/brown red.
The female above is new to my flock and I do not have an example of a male counterpart. From what I know it would look similar to the male above but red factored. (?)



What is the difference in the genetics of these two hens? Clearly there is something that makes them different though I think of both as birchen.

(If anyone knows the genetics of the hen behind the female I believe to be red birchen, that would be awesome! I have been stumped by her color for years.)

 

[nicalandia]

They are not Birchen, they are what is called undermelanized extended black, which could mean just Extended Black(E/E) without Melanotic an Pg(which is both a pattern gene and a melanin booster) or Heterozygous Extended Black(often E/eWh) for example. Black Sex Linked hens, they would appear to be Birchen, but are in fact Heterozygous Extended Black

 

[sjango]

Thank you @nicalandia! Is this in reference to the second hen in particular? If so, what about the all black hen in the first photo? Any ideas on the female in the background of the last photo?

Thank you so much again, this alone is very enlightening!

 

[nicalandia]

Thank you @nicalandia! Is this in reference to the second hen in particular? If so, what about the all black hen in the first photo? Any ideas on the female in the background of the last photo?

Thank you so much again, this alone is very enlightening!

For all birds, they appear to be extended black at the e locus

 

[sjango]

Awesome, you're the best!