What should we do? He looks healthy and his horns are small but looking healthy too. I don't know what he has to eat or how he got there. Or if he can get out. It's about 200 metres squared all fenced off and in a very built up area. What should we do? Theres a way in an out through the fence for humans but there's not anywhere he could go because. We were going to feed him every few days until we figure out what to do.

Edit: thanks for the advice everyone. I'll try and answer everything here. The reason I was reluctant to call is if the deer can get out there is a canal it can go down but if it goes one way it goes through the city centre if it goes the other way it gets to a woods kind of nearby for a deer at least. And potentially its mother could be nearby. I think its trapped because there has been a fence put up recently, I think it was born there and then the fence put up. It can't get out because the way we come in is like a little hole kicked out the bottom of the fence. Way too small for the deer especially with its antlers. We will check up on it tonight and then call animal rescue tomorrow morning.

Edit: just to say we called them and they removed it but we found a doe carcass last week which looked half eaten and the rest looked as if it had been tossed onto a bonfire