Over the years of feeding birds, I have noticed a correlation between the amount of activity at the feeder and the approach of a significant storm. This is especially true in the winter.
When a snow storm is nearing the area, the birds begin to act very similar to panicked supermarket shoppers stocking up on supplies. Suddenly, there is a much larger contingent of local birds than usual all wanting to take a turn on the feeder. I have gotten to where I trust their word more than the local weathermen.
The unusual thing about these photos is the number of Northern Cardinals at the feeder. Cardinals are really nasty birds. You may think they are beautiful and, yeah, I guess they are, but the have very nasty personalities. Plus, they are always wanting to hog the feeder. They will get on the feeder and sit there eating seeds and chasing away anyone else who tries to land - including other cardinals.
They are also very territorial. They are monogamous birds - at least through one breeding season - and once they pair off, they claim a territory and defend it pretty intensely. The feeder is more or less considered a neutral zone, but if a pair from a territory a little farther afield shows up, there will be a major brawl.
In this photo, there are thirteen Cardinals; some are pairs, some are not. What is interesting is that they suspended the normal animosity shown to one another so that they could all have a chance to get some seed. These birds have to represent several acres of territories in the surrounding neighborhood and some may even normally live a couple of streets over, but they are all here because of the weather.
Most of the pictures focus on cardinals because I thought it was so unusual to see so many of them all at one time, but cardinals were not the only birds coming to the feeder during the storm. Here is a photo which is more representative of the variety of birds that appeared. They include Red-bellied Woodpeckers, Tufted Titmice, House Finches, Carolina Chickadees, Snow Buntings and what looks like a female Red-winged Blackbird. In other words, many of the seed eating birds in the neighborhood were showing up.
It turns out, there is a sensory structure in many birds that actually "warns" them about an approaching storm. I don't think it is too well known and I never heard anything about it until recently. I will go into more detail about it tomorrow.