Mad Blackbird

I have a couple of pairs of blackbirds visiting my garden daily.  They do not nest here because I have a cat (interested in mice usually).  For several days last week I watched a male bird picking up dead leaves in his beak and running towards another male blackbird, then running back to where it had started and repeating this six or seven times.  It then put down the leaf and picked up another and repeated this behaviour.  There wasn't any real aggresion shown towards the other male bird, nor did the challenged bird respond with aggresion.  There did not seem to be any vocal communication between them.  It only seemed to do this behaviour with other males.  Has anyone else seen this behaviour?

I'm always look forward to seeing the wonderful green of the leaf buds coming into life you don't see any other time of year and the first swallow around the 15th April.  Spring, Spring Spring.