They hunt in packs 'ere -usually of about 10 birds but can be as many as 20 or 30 at a time.
Last week I had a very sad experience when one of the youngsters smashed into my bedroom window early in the morning. When I got up- a couple of hours later it was lying on its back with its feet wiggling in the air. I rescued it and supported it amongst the plants - it was out for the count but certainly hadn't broken its neck. I checked on it at 10am before I took the dogs out but, again. it was on its back with its feet wiggling in the air and it was now raining on it. Action was needed so I picked it up and made it comfortable and warm inside a covered plant propagater. I even tried to give it a drink by syringing water into its huge beak which it obliged by opening it. It did seem to be a bit more with it and was grateful for another drink so I checked on it every couple of hours giving it more water. At 10pm - the last dog trip out time - I looked in on it and it did seem to still be a bit more 'with it' - a lot of its family had been around looking for it and did discover where it was but they couldn't get at it. I was not sure if they would have pecked it to death.
The next morning it had died. I know now that magpies do indeed mourn their dead - I have never had so many visitors and they saw that I buried it. They all kept away for three full days - I'm sure they blamed me for its demise.