Four bantams in winter, are they enough to keep warm?

[thecatumbrella]

I don't have the breeds you do, but have a flock of Silkies. The feathered coats they wear keep them plenty warm. (Live in zone 5)

Silkies are shockingly tough birds! I'm mostly worried about the d'Uccle. She's not as small as a Serama, but she's pretty svelte compared to the Pekins (or even a Silkie).