Standing water freezes, but water sources do not. We see seagulls here all the time. They're drawn to our asphalt parking lots, which warm up nicely.
On any sunny day, what was frozen will melt somewhere, at least a little bit, and especially so if it is near a dark, absorptive color.
On cold dark days, most birds use their secret stash, or even their fat reserves, but the ones who winter here typically have a moist diet anyway, finding insects under leaves and such. Also, you'd be surprised how many water sources there are in say a quarter mile radius. Even the dew or frost in the morning is enough to sustain a small bird.
It's about sixty here, and I just went out to chop some wood. Boy! Did it warm up quickly! First the sweater came off, and I was tempted to remove my flannel shirt, but prudence prevailed, and I came back inside to cool off.
It's about sixty here
SIXTY?? Well, that's about thirty degrees warmer than it is here. Not fair, hogging all the global warming back there. :-(