A bit of gentle weeding supplemented a rat poison check, which was just lightly nibbled. There's still a bit of snow on the site, but around the weeds it had melted, almost as though the weed had a little heater in it. It may have been simply that the weed stopped as much snow settling at that point too.
The ground is now very wet, with a couple of puddles of standing water where the snow has melted. I didn't think there was enough snow to flood the ground so maybe the ground is frozen below the surface stopping the melt water draining away properly. When the ground is so wet it quickly becomes a quagmire if it gets walked on, so I'll stick to the margins for now.