I have also noticed the bees in my girls feed. Had a bee guy come out and help me understand why they are there. He also said that since we have had tons of rainy days the bees need an alternate source of food. Since my girls are still eating and drinking I have decided to do nothing. Their numbers have also gone down but there are a few hangers on. Mine are wild honey bees and our neighborhood needs the help with gardens and such. I hope they make it through the winter.