Pigeon sitting on fence for 90 mins

Hi all,

A pigeon has been sitting on the fence of the house opposite me for around an hour and a half. It's barely moved and even when I walk within a couple of feet it doesn't respond. 

 Is there something up with it and if so what can I do to help? I can't get really close to it as it's not in my garden. I thought it might be dehydrated. If so could I skoosh some water on it?