those are brown reds I bet. Cant see the faces good in all of them. Chick 2 is for sure though. See around the beak, it has a reddish brown tint. also wings are brownish , not true black.
that's all a birchen chicks shows for color.
As they mature males will look almost just like a bb red male but without the triangle patch in the lower wing.
Hens will remain mostly black but have color in their hackles and usually a laced breast in the same color. For brown reds, this would be red.
On the silvers, it would be the same, just silver in place of the red. Chicks will have a faint silver face on black too.
only other possibility would be blacks with a lot of red leakage in them. But Im betting near 99% they are birchens