I am concerned ,as of yesterday I found several thin longish feathers in the brooder, They seem blackish . I do have 2 black Silkies in there and they are a wee bit larger thn most of the rest of them. I see all are preening and I need for someone to advise me on what is going on. Brooder is currently 85 degrees as advised . I am in Tropical type climate/Hawaii. I know it is supposed to be a 5 degree decrease each week.They were hatched out on Sept 24th and I received them the 27th. I tried the yogurt today and not good results I will retry next time perhaps mixed with their chickstarter. How may I help them if I need to take any action at all?