national wildlife health center (in madison, w00t) released its findings. the cause of death was epic fail - the birds killed themselves.
some un-permitted fireworks are thought to have spooked the birds, disorienting them and causing them to crash into buildings or the ground.
apparently the reason we don't see this after our own rhythm and booms is that warner park is not a roosting area for most birds. just the geese......uh oh!