Yah, neither of those would be good.Well, maybe @aart can tell about gauging moisture in the air? I really don't know. I am going to assume if you have frost on your birds in the mornings, that would not be good or if your windows are frosted on the inside same thing
The red circled areas between rafters, on both roof eaves, what do they look like on the outside? It looks like they are closed off(don't see any light coming thru) that's the best place for winter ventilation.
Also, this window should have 1/2" HC on it, maybe it does and it's not showing up in the pic?