What is this crow up to?

[~T~]

A year or so back in about Jan or Feb a large carrion crow would do this exact behaviour beside where I work. It would either perch in a tree (and almost always the same tree in the same branch) or on an aerial of an office diagonal to mine. It would spend most of the morning just calling and calling with it's head bobbing and return several times during the day though would not call for as long then. I never saw any other corvids around except maybe a few magpies but neither seemed bothered by each others presence. It kept this calling up for a good few weeks then one day was gone. What Dogghound says does seem to make sense as it was a lone adult crow and this was outside the breeding season. Perhaps he found a mate in the end Funny thing is people in my office were convinced it was a raven as it certainly puffed itself up during it's calling and really did look very large,