There are many more birds than space on the feeder, where at most they can sit four abreast. When there are this many, they spend more time knocking each other off the feeder than actually eating.
When startled away from the feeding area, some of the birds roost on the tree in front of the window and wait for a chance to head for the feeder or the area around the dying pumpkin.
There are several other photos I took this morning of the bird bonanza; click through any of these here to look at them.
If I stand sufficiently still while looking out the window, the birds forget that I'm here. But they seem to see motion very well, and startle easily. That's a survival trait, of course. When taking out the trash on Monday, I found a single wing on the ground, it being the only evidence of one bird that didn't move soon enough.