Oh gosh... Adding your general location will help folks make their best possible suggestions at a glance.

Maybe google it up, what are appropriate abatement methods for your area. I'm fortunate enough to have a swallow nesting on my patio. And inside coop I use (if needed) a permethrin based "horse fly spray", safe for use on poultry and when used correctly effective at getting rid of lice, mites. fleas, etc.. I originally bought it to keep mosquitoes off my goats.
Also, if you are keeping those species together long term, maybe contact your department of agriculture and find out if black head is an issue in YOUR area.. it has not been an issue at my location, and with some fecal testing and treatment IF needed, can diminish the likely hood of occurrence.. but now I've mentioned it in case it wasn't on your radar yet.
I don't think there's an age limit to when poultry can get pox, but I would presume your chickens are next and just fighting it off a little better maybe because they are stronger at that age. BUT I could be wrong! I would still presume they *SHOULD* be okay even if they do contract it.