Red-winged Blackbird, female

I stole this image from the internet, but there were nine of these on my feeder last weekend. I searched the bird book and decided it must be a female red-winged blackbird, but why so many of them with no males? After further research I learned that juvenile birds look like females and also that the birds segregate such that the juveniles and females forage together and the males forage together, explaining why they all looked like females on the feeder.