Can chickens catch colds?

[ChickenMomsince2025]

My BO has been sneezing once every a few days and when she shakes her head, clear liquid discharges from her nose. Whenever i hug her she shivers. It's been going on over a month. Now two other chickens are discharging clear liquid from their nose. They discharge more frequently when it's warmer like in my car or inside the house.
The weather has been brutal and it's their first winter. I started giving them supplemental heat when it's single digit at night. I get bad rap for giving them heat, but I can visibly tell they're struggling. BO and RIR got frostbite a few weeks ago. Nothing serious, tiny specks at the very top of their combs. That's when I started using brooder plates on extremely cold nights.
I have 6 and 2 of them are going through molt. Last a few days, all 6 of them are content to stay in the coop most part of the day (no supplemental heat during the day). They came out to the run to eat and drink and then went straight back to the coop. This is not normal for them. Are they all sick? Should I consult a vet?

 

[neo71665]

Yes they can. It's not uncommon for birds to stay in the coop when it's cold. Mine also do it when it hits over 100 degrees.

 

[ChickenMomsince2025]

Yes they can. It's not uncommon for birds to stay in the coop when it's cold. Mine also do it when it hits over 100 degrees.

What about the clear discharge from their nose? Should I be concerned?

 

[chooki]

How old are you birds? When you mentioned about the single digit temperature, are we talking about Celsius or Fahrenheit?